{"gene":"PIK3CA","run_date":"2026-06-10T06:43:35","timeline":{"discoveries":[{"year":2007,"finding":"Fifteen rare cancer-derived PIK3CA mutants were examined and 14 showed gain-of-function: they induced rapamycin-sensitive oncogenic transformation of chicken embryo fibroblasts, constitutively activated Akt and TOR-mediated signaling, and showed enhanced lipid kinase activity in vitro. Three mechanistic groups were proposed based on structural mapping: C2 domain mutants increase positive surface charge potentially enhancing membrane recruitment; helical domain mutants affect protein-protein interaction surfaces; kinase domain mutants alter the activation loop hinge position.","method":"In vitro lipid kinase assay, oncogenic transformation assay (chicken embryo fibroblasts), Akt/TOR signaling assays, structural modeling with mutagenesis","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"High","confidence_rationale":"Tier 1 / Strong — in vitro enzymatic assay combined with cell-based transformation assay and structural analysis across 15 mutants with mutagenesis validation","pmids":["17376864"],"is_preprint":false},{"year":2008,"finding":"Crystal structure of the p110α/p85α complex revealed that the majority of oncogenic PIK3CA mutations occur at interfaces between p110 domains and between p110 and p85 domains. At these positions, mutations disrupt inter-domain interactions causing conformational changes in the kinase domain that increase enzymatic activity. The structure also showed that membrane interaction is mediated by the iSH2 domain of p85.","method":"X-ray crystallography of p110α/p85α complex with structural mapping of cancer mutations","journal":"Cell cycle (Georgetown, Tex.)","confidence":"High","confidence_rationale":"Tier 1 / Strong — crystal structure with functional interpretation of oncogenic mutations; foundational structural paper","pmids":["18418043"],"is_preprint":false},{"year":2019,"finding":"Double PIK3CA mutations occurring in cis on the same allele (found in 12–15% of breast cancers) result in increased PI3K lipid kinase activity, enhanced downstream AKT signaling, increased cell proliferation, and tumor growth compared to single hotspot mutations. Biochemical mechanisms include increased disruption of p110α binding to the inhibitory subunit p85α (relieving catalytic inhibition) and increased p110α membrane lipid binding. Double mutations predict enhanced sensitivity to PI3Kα inhibitors.","method":"In vitro PI3K activity assay, cell proliferation assays, tumor growth models, biochemical p85α binding assays, cancer genome analysis","journal":"Science (New York, N.Y.)","confidence":"High","confidence_rationale":"Tier 1 / Strong — multiple orthogonal biochemical and cellular methods in one study with mechanistic dissection of p85α binding and membrane lipid interaction","pmids":["31699932"],"is_preprint":false},{"year":2016,"finding":"NEDD4L was identified as the E3 ubiquitin ligase that catalyzes PIK3CA polyubiquitination, leading to proteasome-dependent degradation of p110α. NEDD4L ubiquitinates both free and regulatory subunit-bound PIK3CA but does not ubiquitinate the regulatory subunit p85. Overexpression of NEDD4L accelerates PIK3CA turnover, while suppression of NEDD4L increases PIK3CA levels and paradoxically decreases AKT activation, indicating NEDD4L is required for maintenance of PI3K-AKT signaling.","method":"Co-immunoprecipitation, ubiquitination assay, proteasome inhibitor treatment, overexpression and knockdown of NEDD4L, Western blotting for AKT phosphorylation","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1/2 / Moderate — direct biochemical ubiquitination assay with Co-IP, gain and loss-of-function experiments, and functional readout of AKT signaling in single study","pmids":["27339899"],"is_preprint":false},{"year":2018,"finding":"TRAF6 interacts with PIK3CA (p110α) and promotes its non-proteolytic polyubiquitination under serum stimulation. TRAF6 ubiquitinates both individual and regulatory subunit-bound PIK3CA but does not ubiquitinate the regulatory subunit. TRAF6 overexpression greatly enhances PI3K activation, leading to increased AKT phosphorylation and cell growth, establishing TRAF6 as a novel activating E3 ligase for PIK3CA.","method":"Co-immunoprecipitation, ubiquitination assay, TRAF6 overexpression with AKT phosphorylation readout, cell growth assay","journal":"FEBS letters","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — reciprocal Co-IP and direct ubiquitination assay with functional downstream readout, single lab","pmids":["29729098"],"is_preprint":false},{"year":2017,"finding":"PIK3CA mutant cancer cells exhibit increased reliance on glucose metabolism and specifically require the TCA cycle enzyme OGDH (2-oxoglutarate dehydrogenase). OGDH suppression in PIK3CA-mutant cells increases 2-oxoglutarate levels, leading to aspartate depletion, deregulation of the malate-aspartate shuttle, impaired cytoplasmic NAD+ regeneration, and a specific proliferative block due to inability to maintain NAD+/NADH homeostasis.","method":"Genome-scale RNAi loss-of-function screening in cancer cell lines, metabolic flux studies, OGDH knockdown, exogenous metabolite supplementation, NAD+/NADH measurement","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"High","confidence_rationale":"Tier 2 / Strong — genome-scale functional screen combined with orthogonal metabolic studies and mechanistic rescue experiments","pmids":["28396387"],"is_preprint":false},{"year":2017,"finding":"Expression of the Pik3ca H1047R hotspot mutation from its endogenous locus in mouse cells induces centrosome amplification through a pathway involving AKT, ROCK, and CDK2/Cyclin E-nucleophosmin. Mutant Pik3ca also increases cellular tolerance to spontaneous genome doubling in vitro and in mouse tissues.","method":"Conditional knock-in mouse model (endogenous locus), centrosome counting, pathway inhibitor experiments (AKT, ROCK, CDK2 inhibitors), genome ploidy analysis","journal":"Nature communications","confidence":"High","confidence_rationale":"Tier 2 / Strong — endogenous knock-in model with pharmacological pathway dissection (AKT, ROCK, CDK2 inhibitors) establishing mechanistic pathway","pmids":["29170395"],"is_preprint":false},{"year":2015,"finding":"PIK3CA H1047R expression in lineage-committed basal (Lgr5+) and luminal (K8+) mammary epithelial cells induces cell dedifferentiation into a multipotent stem-like state, demonstrated by in situ genetic lineage tracing and limiting dilution transplantation assays. The cell of origin of PIK3CA H1047R tumors dictates their malignancy.","method":"In situ genetic lineage tracing, limiting dilution transplantation, conditional PIK3CA H1047R knock-in mouse model","journal":"Nature","confidence":"High","confidence_rationale":"Tier 2 / Strong — in vivo lineage tracing with functional transplantation assays in knock-in model, multiple orthogonal approaches","pmids":["26266975"],"is_preprint":false},{"year":2015,"finding":"PIK3CA H1047R expression alone failed to promote lung tumor formation but dramatically enhanced tumorigenesis initiated by KRAS G12D in genetically engineered mouse models. Oncogenic cooperation was accompanied by PI3Kα-mediated regulation of c-MYC, GSK3β, p27KIP1, survivin, and RB pathway components, resulting in accelerated cell division, indicating that PI3'-lipid signaling remains rate-limiting for cell-cycle progression of early-stage KRAS-initiated lung cells.","method":"Genetically engineered mouse models (GEM), compound KRAS/PIK3CA knock-in, Western blotting for pathway components, cell cycle analysis","journal":"Cancer research","confidence":"High","confidence_rationale":"Tier 2 / Strong — genetic epistasis in GEM models with mechanistic pathway analysis, multiple downstream targets identified","pmids":["26567140"],"is_preprint":false},{"year":2015,"finding":"PIK3CA hotspot mutations (E542K, E545K, H1047R) cause chronic activation of AKT and dysregulation of angiogenic factors, and produce abnormal endothelial cell morphology when expressed in HUVECs. The p110α-specific inhibitor BYL719 restores all abnormal phenotypes in both PIK3CA-mutant and TEK-mutant HUVECs, demonstrating that PIK3CA and TEK mutations operate via the same PI3K-dependent pathogenic pathway in venous malformations.","method":"Expression of PIK3CA mutants in HUVECs, AKT phosphorylation assays, angiogenic factor measurement, morphology assays, pharmacological rescue with BYL719","journal":"American journal of human genetics","confidence":"High","confidence_rationale":"Tier 2 / Strong — direct functional expression in primary endothelial cells with pharmacological rescue and multiple orthogonal phenotypic readouts","pmids":["26637981"],"is_preprint":false},{"year":2022,"finding":"p85β (PIK3R2) dissociates from p110α helical domain mutant protein and translocates into the nucleus through a nuclear localization sequence (NLS). Nuclear p85β recruits deubiquitinase USP7 to stabilize EZH1 and EZH2, enhancing H3K27 trimethylation. Knockout of p85β or p85β NLS mutant reduces growth of PIK3CA helical domain mutant tumors. Combination of alpelisib and EZH inhibitor tazemetostat induced regression of PIK3CA helical domain mutant xenografts but not WT or kinase domain mutant tumors.","method":"Co-immunoprecipitation, nuclear fractionation, p85β NLS mutagenesis, USP7 interaction assay, EZH1/2 stability assay, H3K27me3 ChIP, xenograft models, genetic knockout","journal":"Nature communications","confidence":"High","confidence_rationale":"Tier 2 / Strong — multiple orthogonal methods (Co-IP, fractionation, mutagenesis, in vivo models) establishing novel nuclear mechanism specific to helical domain mutations","pmids":["35418124"],"is_preprint":false},{"year":2016,"finding":"p53 represses PIK3CA promoter activity through direct binding to p53 binding sequences in the PIK3CA promoter, and this repression depends on p53 phosphorylation at serine 46. In cisplatin-sensitive cells, cisplatin-induced p53 activation dynamically alters p53 occupancy at the PIK3CA promoter and attenuates PI3K/AKT signaling. In resistant cells, loss of p53 serine 46 phosphorylation abolishes PIK3CA promoter repression, resulting in sustained PIK3CA expression and cell survival.","method":"Promoter-luciferase reporter assay, chromatin immunoprecipitation (ChIP), p53 phosphorylation site mutagenesis (S46A), Western blotting, bioluminescent imaging in vivo","journal":"Molecular oncology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — ChIP and reporter assays with mutagenesis in single lab, multiple cell lines tested","pmids":["27401370"],"is_preprint":false},{"year":2015,"finding":"Functional assessment of PIK3CA variants using high-throughput barcoded expression clones showed that PIK3CA variant oncogenic activity correlates imperfectly with mutation frequency in breast cancer. Mutations occurring above 5% frequency were significantly more oncogenic than wild-type in all assays, but lower frequency mutations varied from weak to strong oncogenicity. Proteomic profiling revealed variant-specific activation of PI3K signaling as well as MEK1/2 pathway activation depending on the specific PIK3CA mutation.","method":"High-throughput barcoded clone library, in vitro cell growth assay, soft agar transformation assay, in vivo tumor growth, proteomic profiling, therapeutic sensitivity assays","journal":"Cancer research","confidence":"High","confidence_rationale":"Tier 2 / Strong — multiple orthogonal functional assays across many variants with proteomics in a single systematic study","pmids":["26627007"],"is_preprint":false},{"year":2015,"finding":"PIK3CA mutations can initiate pancreatic tumorigenesis: expression of constitutively active PIK3CA in mouse pancreas increased acinar-to-ductal metaplasia and pancreatic intraepithelial neoplasms (PanINs) as early as 10 days of age, with invasive pancreatic ductal adenocarcinoma by 20 days. These PIK3CA-mutant cancers showed phosphorylation of ERK1/2 in addition to PI3K pathway activation; ERK1/2 phosphorylation was diminished by dual PI3K/mTOR inhibition.","method":"Transgenic mouse models with pancreas-specific PIK3CA expression, histopathology, immunostaining, PI3K/mTOR inhibitor treatment","journal":"Oncogenesis","confidence":"High","confidence_rationale":"Tier 2 / Moderate — in vivo genetic model with mechanistic pathway analysis and pharmacological intervention","pmids":["26436951"],"is_preprint":false},{"year":2021,"finding":"Growth of cerebral cavernous malformations (CCMs) requires both somatic gain-of-function mutations in PIK3CA and loss-of-function mutations in CCM complex genes (KRIT1/CCM2/PDCD10) in the same endothelial cells. Mouse models showed that PIK3CA gain-of-function augments mTOR signaling in endothelial cells, and that both CCM loss-of-function and increased KLF4 (downstream of MEKK3) augment mTOR signaling. mTORC1 inhibitor rapamycin effectively blocked CCM formation in mouse models.","method":"Mouse genetic models, somatic mutation analysis of human CCMs, mTOR pathway analysis, rapamycin treatment in vivo","journal":"Nature","confidence":"High","confidence_rationale":"Tier 2 / Strong — genetic epistasis in mouse models combined with human tissue mutation analysis and pharmacological rescue","pmids":["33910229"],"is_preprint":false},{"year":2015,"finding":"Induction of PIK3CA H1047R in mouse mammary glands with constitutive activated Her2/Neu resulted in accelerated mammary tumorigenesis with enhanced metastatic potential. PIK3CA H1047R expression caused robust PI3K/AKT signaling activation but attenuated Her2/Her3 signaling. Tumors that escaped PI3K dependence after PIK3CA H1047R inactivation did so through compensatory ERK activation, which could be blocked by combined inhibition of Her2 and MEK.","method":"Compound transgenic mouse model (Her2 + inducible PIK3CA H1047R), deinduction of PIK3CA H1047R, Western blotting for pathway components, MEK and Her2 inhibitor treatment","journal":"Oncogene","confidence":"High","confidence_rationale":"Tier 2 / Strong — in vivo compound genetic model with inducible system and pharmacological pathway dissection identifying compensatory ERK mechanism","pmids":["26640141"],"is_preprint":false},{"year":2018,"finding":"In activated T and B lymphocytes, class I PI3K (indexed by PIP3) activity is spatially restricted to the microtubule-organizing center and then to one pole of the mitotic spindle, creating asymmetry. Asymmetric PI3K activity co-localizes with asymmetric distribution of antigen receptor components and glucose transporters (whose trafficking is PI3K-dependent). Perturbation of class I PI3K activity disrupts asymmetry of upstream antigen receptors and downstream glucose transporter trafficking, establishing PI3K as a core organizer of lymphocyte polarity and asymmetric cell division.","method":"PIP3 immunostaining in dividing lymphocytes, live imaging, PI3K inhibitor perturbation, glucose transporter trafficking assay","journal":"Cell reports","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct localization with functional perturbation in primary lymphocytes, single lab","pmids":["29420173"],"is_preprint":false},{"year":2023,"finding":"PIK3CA E545K mutation negatively regulates SIRT4 expression through the epigenetic regulator EP300, independently of the canonical mTORC1 pathway. PIK3CA-E545K-induced SIRT4 downregulation promoted cell proliferation, migration, radiation-induced DNA repair, and reduced apoptosis in cervical cancer cells. SIRT4 modulates glutamine metabolism and cellular apoptosis by negatively regulating glutamate pyruvate transaminase GPT1. PI3K inhibitor BYL719 (but not mTOR inhibitors) had synergistic radiosensitizing effects by inhibiting glutamine metabolism.","method":"PIK3CA mutant cell line models, EP300 inhibition, SIRT4 overexpression/knockdown, GPT1 activity assay, glutamine metabolism measurement, radiosensitivity assay, in vivo xenograft","journal":"Cancer letters","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — mechanistic pathway dissection with multiple functional readouts, single lab, mTOR independence established pharmacologically","pmids":["36646410"],"is_preprint":false},{"year":2007,"finding":"Overexpression of wild-type PIK3CA and its two common mutants K545E and H1047R significantly enhanced anchorage-independent growth activity and migration activity of immortalized human airway epithelial cells (16HBE14o-), with the effects of K545E and H1047R mutants being more pronounced than wild-type.","method":"Ectopic expression in human airway epithelial cell line, anchorage-independent growth assay (soft agar), migration assay","journal":"Pathology international","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct functional assays comparing wild-type vs mutant PIK3CA in human epithelial cells, single lab","pmids":["17803655"],"is_preprint":false},{"year":2016,"finding":"Specific knockdown of mutant PIK3CA in urothelial carcinoma (UC) cell lines inhibited PI3K pathway activation, cell proliferation, migration, anchorage-independent growth, and in vivo tumor growth, establishing mutant PIK3CA as a potent oncogenic driver in UC. Sensitivity to the class I PI3K inhibitor GDC-0941 was dependent on hotspot PIK3CA mutation status; cells with co-occurring TSC1, PTEN, AKT1, or RAS mutations were less sensitive.","method":"Retrovirus-mediated shRNA knockdown of mutant PIK3CA, proliferation, migration, anchorage-independent growth assays, in vivo tumor growth, GDC-0941 sensitivity panel","journal":"BMC cancer","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — specific mutant knockdown with multiple phenotypic readouts and in vivo validation, single lab","pmids":["27465249"],"is_preprint":false},{"year":2014,"finding":"PIK3CA isoform-specific knockdown experiments in multiple myeloma cells showed that PIK3CA (p110α) is of paramount importance for constitutive AKT activity in MM cells. Unlike knockdown of PIK3CB, PIK3CD, or PIK3CG, only PIK3CA knockdown or pharmacological PIK3CA inhibition with BYL-719 was sufficient to induce cell death in a sizeable subgroup of MM samples.","method":"Isoform-specific shRNA knockdown (PIK3CA, PIK3CB, PIK3CD, PIK3CG), isoform-specific inhibitors (BYL-719, TGX-221, CAL-101, CAY10505), AKT phosphorylation assay, cell viability assay","journal":"British journal of haematology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — isoform-specific genetic and pharmacological approaches across multiple MM samples, single lab","pmids":["24766330"],"is_preprint":false},{"year":2012,"finding":"Germline PIK3CA mutations in Cowden syndrome patients result in significantly increased phospho-Thr308-AKT and increased cellular PIP3 levels compared to wild-type, directly demonstrating that these germline PIK3CA variants activate PI3K pathway signaling.","method":"Cell signaling assays (phospho-AKT, PIP3 measurement) in patient-derived cells with germline PIK3CA mutations","journal":"American journal of human genetics","confidence":"Medium","confidence_rationale":"Tier 2 / Weak — direct functional signaling measurement in patient cells, single study, limited mechanistic detail in abstract","pmids":["23246288"],"is_preprint":false}],"current_model":"PIK3CA encodes p110α, the catalytic subunit of class IA PI3K, which functions as a lipid kinase generating PIP3 to activate AKT-mTOR signaling; oncogenic mutations (clustered in the helical domain, e.g., E542K/E545K, and kinase domain, e.g., H1047R) gain function by disrupting inhibitory p85α interactions and enhancing membrane lipid binding, leading to constitutive PI3K activation, and are regulated post-translationally by NEDD4L-mediated proteasomal degradation and TRAF6-mediated activating ubiquitination; helical domain mutations additionally trigger nuclear translocation of p85β to enhance EZH1/2-mediated H3K27 trimethylation, and mutant PIK3CA drives centrosome amplification via AKT-ROCK-CDK2/CyclinE-nucleophosmin, mammary cell dedifferentiation to multipotency, and metabolic reprogramming including glucose dependency and glutamine pathway alterations."},"narrative":{"mechanistic_narrative":"PIK3CA encodes p110α, the catalytic subunit of class IA PI3K, a lipid kinase whose activity drives AKT-TOR signaling and downstream control of proliferation, migration, and metabolism; cancer-derived mutations confer gain-of-function by constitutively activating this pathway and transforming cells [PMID:17376864]. Structurally, oncogenic substitutions cluster at interfaces between p110 domains and between p110 and the regulatory subunit p85α, where they disrupt inhibitory inter-domain contacts and provoke conformational changes in the kinase domain that elevate enzymatic output [PMID:18418043]; the same logic extends to compound cis double mutations, which further relieve p85α inhibition and enhance membrane lipid binding to give supra-additive kinase activity and tumor growth [PMID:31699932]. Beyond the canonical p110α/p85α/AKT axis, helical-domain mutants engage a distinct nuclear program in which dissociated p85β (PIK3R2) translocates to the nucleus, recruits the deubiquitinase USP7 to stabilize EZH1/EZH2, and enhances H3K27 trimethylation, a vulnerability exploited by combined PI3Kα and EZH inhibition [PMID:35418124]. p110α abundance and activity are tuned post-translationally by opposing E3 ligases: NEDD4L drives proteasomal degradation while also being required to sustain AKT signaling [PMID:27339899], and TRAF6 mediates non-proteolytic activating ubiquitination upon serum stimulation [PMID:29729098]; transcriptionally, p53 represses the PIK3CA promoter in a serine-46 phosphorylation-dependent manner [PMID:27401370]. Mutant PIK3CA reprograms cell behavior and metabolism—inducing centrosome amplification through an AKT-ROCK-CDK2/Cyclin E-nucleophosmin pathway [PMID:29170395], driving mammary epithelial dedifferentiation to a multipotent stem-like state [PMID:26266975], and creating dependencies on glucose metabolism and the TCA enzyme OGDH for NAD+/NADH homeostasis [PMID:28396387]. As a disease gene, PIK3CA is an oncogenic driver across breast, urothelial, pancreatic, lung, and myeloma contexts, frequently cooperating with KRAS or HER2 and converging on PI3Kα inhibitors such as BYL719/alpelisib [PMID:26567140, PMID:26640141, PMID:27465249, PMID:24766330], and somatic or germline activating mutations underlie vascular malformations, cerebral cavernous malformations, and Cowden syndrome [PMID:26637981, PMID:33910229, PMID:23246288].","teleology":[{"year":2007,"claim":"Established that diverse cancer-derived PIK3CA mutations are bona fide gain-of-function alleles rather than passengers, defining PIK3CA as an oncogene acting through lipid kinase activity and AKT-TOR signaling.","evidence":"In vitro lipid kinase assays, chicken embryo fibroblast transformation, and AKT/TOR signaling readouts across 15 mutants with structural mapping","pmids":["17376864"],"confidence":"High","gaps":["Three mechanistic groups proposed from modeling rather than direct structural determination","Did not resolve how each mutation class alters the enzyme at atomic resolution"]},{"year":2007,"claim":"Confirmed in human epithelial cells that common mutants exceed wild-type in promoting transformed phenotypes, linking mutation status to oncogenic potency.","evidence":"Ectopic expression of WT, K545E, and H1047R in airway epithelial cells with soft-agar and migration assays","pmids":["17803655"],"confidence":"Medium","gaps":["Overexpression rather than endogenous expression","No biochemical link to kinase output in these cells"]},{"year":2008,"claim":"Provided the structural basis for activation by showing oncogenic mutations cluster at p110-p110 and p110-p85 interfaces, disrupting inhibitory contacts and reshaping the kinase domain.","evidence":"X-ray crystallography of the p110α/p85α complex with mapping of cancer mutations","pmids":["18418043"],"confidence":"High","gaps":["Static structure does not capture membrane-bound active conformation","Helical vs kinase domain mutant mechanisms not fully separated structurally"]},{"year":2012,"claim":"Demonstrated that germline PIK3CA variants activate the pathway in patient cells, extending oncogenic mechanisms to a heritable overgrowth syndrome.","evidence":"Phospho-Thr308-AKT and PIP3 measurements in Cowden syndrome patient-derived cells","pmids":["23246288"],"confidence":"Medium","gaps":["Limited mechanistic detail beyond signaling readouts","Single study, small patient cohort"]},{"year":2014,"claim":"Distinguished p110α from other class I isoforms as the non-redundant driver of constitutive AKT activity in a tumor context, supporting isoform-selective therapy.","evidence":"Isoform-specific shRNA and inhibitors (BYL-719 vs TGX-221, CAL-101, CAY10505) in multiple myeloma samples","pmids":["24766330"],"confidence":"Medium","gaps":["Single lab","Mechanism of isoform selectivity in MM not defined"]},{"year":2015,"claim":"Showed mutant PIK3CA reprograms cell identity by dedifferentiating committed mammary epithelial cells to a multipotent state, with cell-of-origin dictating tumor malignancy.","evidence":"In situ lineage tracing and limiting-dilution transplantation in a conditional H1047R knock-in mouse","pmids":["26266975"],"confidence":"High","gaps":["Molecular effectors of dedifferentiation not identified","Generalizability beyond mammary lineage unknown"]},{"year":2015,"claim":"Established genetic cooperation with KRAS and HER2 and identified compensatory ERK signaling as an escape route, framing PI3K as rate-limiting in early oncogenesis.","evidence":"Compound GEM models (KRAS/PIK3CA; Her2/inducible H1047R) with pathway blotting and MEK/Her2 inhibitor experiments","pmids":["26567140","26640141"],"confidence":"High","gaps":["Pancreatic, lung, and mammary contexts may differ in cooperating effectors","ERK reactivation mechanism after PI3K loss not fully mapped"]},{"year":2015,"claim":"Demonstrated PIK3CA can initiate pancreatic tumorigenesis and that PI3K activation co-engages ERK signaling, broadening the oncogenic tissue spectrum.","evidence":"Pancreas-specific PIK3CA transgenic mice with histopathology and PI3K/mTOR inhibitor treatment","pmids":["26436951"],"confidence":"High","gaps":["Link between PI3K and ERK activation mechanistically indirect","Constitutively active construct rather than endogenous hotspot allele"]},{"year":2015,"claim":"Systematically resolved variant-specific oncogenicity, showing potency only imperfectly tracks mutation frequency and that some variants additionally activate MEK1/2.","evidence":"High-throughput barcoded clone library with growth, soft-agar, in vivo, and proteomic profiling","pmids":["26627007"],"confidence":"High","gaps":["Mechanism of MEK co-activation by specific variants unresolved","Overexpression system may not reflect endogenous levels"]},{"year":2015,"claim":"Linked PIK3CA mutations to vascular malformations and showed shared PI3K-dependent pathogenesis with TEK mutations, rescuable by PI3Kα inhibition.","evidence":"PIK3CA and TEK mutant expression in HUVECs with AKT/angiogenic readouts and BYL719 rescue","pmids":["26637981"],"confidence":"High","gaps":["Endothelial-specific effectors downstream of AKT not detailed","In vitro HUVEC model"]},{"year":2016,"claim":"Identified NEDD4L as the E3 ligase driving proteasomal turnover of p110α while paradoxically being required to sustain AKT signaling, revealing nuanced post-translational control.","evidence":"Co-IP, ubiquitination assays, proteasome inhibition, and NEDD4L gain/loss-of-function with AKT readout","pmids":["27339899"],"confidence":"High","gaps":["Mechanism of the paradoxical AKT requirement unexplained","Ubiquitin chain linkage type not defined"]},{"year":2016,"claim":"Defined transcriptional control of PIK3CA by p53, where serine-46 phosphorylation enables promoter repression and its loss confers drug resistance via sustained PIK3CA expression.","evidence":"Promoter-luciferase reporters, ChIP, and S46A mutagenesis in cisplatin-sensitive vs resistant cells","pmids":["27401370"],"confidence":"Medium","gaps":["Single lab","Direct p53 binding site validation limited to reporter and ChIP"]},{"year":2016,"claim":"Confirmed mutant PIK3CA as a targetable driver in urothelial carcinoma, with inhibitor sensitivity gated by co-occurring pathway mutations.","evidence":"Mutant-specific shRNA knockdown and GDC-0941 sensitivity panel with in vivo tumor growth","pmids":["27465249"],"confidence":"Medium","gaps":["Single lab","Mechanism by which TSC1/PTEN/AKT1/RAS mutations reduce sensitivity not dissected"]},{"year":2017,"claim":"Uncovered a metabolic dependency: PIK3CA-mutant cells require OGDH to maintain NAD+/NADH homeostasis via the malate-aspartate shuttle, exposing a metabolic vulnerability.","evidence":"Genome-scale RNAi screen, metabolic flux, OGDH knockdown, and metabolite rescue","pmids":["28396387"],"confidence":"High","gaps":["How PI3K activation establishes OGDH dependency not fully mechanistic","Generalizability across tumor types untested"]},{"year":2017,"claim":"Showed endogenous H1047R drives centrosome amplification and tolerance to genome doubling through a defined AKT-ROCK-CDK2/Cyclin E-nucleophosmin pathway, linking PI3K to genome instability.","evidence":"Conditional endogenous-locus knock-in mouse with centrosome counting and AKT/ROCK/CDK2 inhibitor dissection","pmids":["29170395"],"confidence":"High","gaps":["Connection between PI3K and centrosome machinery indirect","Contribution to tumor evolution in vivo not quantified"]},{"year":2018,"claim":"Identified TRAF6 as an activating, non-proteolytic E3 ligase for p110α under serum stimulation, providing a positive post-translational regulatory arm opposing NEDD4L.","evidence":"Reciprocal Co-IP, ubiquitination assays, and TRAF6 overexpression with AKT and growth readouts","pmids":["29729098"],"confidence":"Medium","gaps":["Single lab","Ubiquitin chain topology and binding partner consequences not fully defined","No loss-of-function validation in physiological setting"]},{"year":2018,"claim":"Revealed a non-oncogenic physiological role: class I PI3K activity is spatially polarized to the MTOC and mitotic spindle pole to organize asymmetric lymphocyte division and receptor/glucose-transporter partitioning.","evidence":"PIP3 immunostaining, live imaging, and PI3K inhibitor perturbation in dividing T and B lymphocytes","pmids":["29420173"],"confidence":"Medium","gaps":["Isoform-specific contribution of p110α not isolated","Mechanism establishing spatial restriction unknown"]},{"year":2019,"claim":"Demonstrated that cis double mutations are functionally synergistic, deepening p85α release and membrane binding to amplify kinase output and predict enhanced inhibitor sensitivity.","evidence":"In vitro PI3K activity, proliferation/tumor models, p85α binding assays, and cancer genome analysis","pmids":["31699932"],"confidence":"High","gaps":["Structural basis of combined effects not crystallographically resolved","Clinical predictiveness requires patient validation"]},{"year":2021,"claim":"Showed that cerebral cavernous malformation growth requires combined PIK3CA gain-of-function and CCM-complex loss-of-function in the same endothelial cells, converging on mTOR and rescuable by rapamycin.","evidence":"Mouse genetic models, human CCM somatic mutation analysis, mTOR pathway analysis, rapamycin treatment","pmids":["33910229"],"confidence":"High","gaps":["Order and timing of the two mutational events in human lesions unclear","Relative contributions of KLF4 vs PI3K to mTOR not quantified"]},{"year":2022,"claim":"Defined a domain-specific noncanonical mechanism whereby helical-domain mutants release p85β to the nucleus to stabilize EZH1/2 via USP7 and boost H3K27me3, creating a mutation-class-specific therapeutic vulnerability.","evidence":"Co-IP, nuclear fractionation, NLS mutagenesis, USP7/EZH stability assays, H3K27me3 ChIP, and alpelisib+tazemetostat xenografts","pmids":["35418124"],"confidence":"High","gaps":["Genome-wide targets of nuclear p85β/EZH program not catalogued","Why only helical mutants release p85β structurally unresolved"]},{"year":2023,"claim":"Identified an mTORC1-independent axis in which E545K suppresses SIRT4 via EP300 to reprogram glutamine metabolism and DNA repair, with PI3Kα inhibition acting as a radiosensitizer.","evidence":"PIK3CA mutant cervical cancer models with EP300 inhibition, SIRT4/GPT1 manipulation, glutamine metabolism and radiosensitivity assays, and xenografts","pmids":["36646410"],"confidence":"Medium","gaps":["Single lab","How E545K signals to EP300 independently of mTORC1 not mechanistically resolved"]},{"year":null,"claim":"How the distinct mutation classes (C2, helical, kinase) selectively wire to canonical AKT-mTOR output versus noncanonical nuclear p85β/EZH and mTOR-independent metabolic programs remains incompletely unified.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No single framework reconciles domain-specific canonical and noncanonical mechanisms","Membrane-bound active-state structure of mutant complexes not resolved","Integration of opposing NEDD4L/TRAF6 regulation in vivo unresolved"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0016740","term_label":"transferase activity","supporting_discovery_ids":[0,1,2,21]},{"term_id":"GO:0008289","term_label":"lipid binding","supporting_discovery_ids":[1,2,21]}],"localization":[{"term_id":"GO:0005886","term_label":"plasma membrane","supporting_discovery_ids":[1,2]},{"term_id":"GO:0005634","term_label":"nucleus","supporting_discovery_ids":[10]},{"term_id":"GO:0005815","term_label":"microtubule organizing center","supporting_discovery_ids":[16]}],"pathway":[{"term_id":"R-HSA-162582","term_label":"Signal 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letters","url":"https://pubmed.ncbi.nlm.nih.gov/36646410","citation_count":25,"is_preprint":false},{"pmid":"29729098","id":"PMC_29729098","title":"TRAF6 interacts with and ubiquitinates PIK3CA to enhance PI3K activation.","date":"2018","source":"FEBS letters","url":"https://pubmed.ncbi.nlm.nih.gov/29729098","citation_count":23,"is_preprint":false},{"pmid":"28550907","id":"PMC_28550907","title":"Analysis of PIK3CA mutations and PI3K pathway proteins in advanced gastric cancer.","date":"2017","source":"The Journal of surgical research","url":"https://pubmed.ncbi.nlm.nih.gov/28550907","citation_count":23,"is_preprint":false},{"pmid":"23768168","id":"PMC_23768168","title":"Carcinogenesis of PIK3CA.","date":"2013","source":"Hereditary cancer in clinical practice","url":"https://pubmed.ncbi.nlm.nih.gov/23768168","citation_count":22,"is_preprint":false},{"pmid":"28577738","id":"PMC_28577738","title":"[PIK3CA-related overgrowth syndrome (PROS)].","date":"2017","source":"Nephrologie & therapeutique","url":"https://pubmed.ncbi.nlm.nih.gov/28577738","citation_count":22,"is_preprint":false},{"pmid":"25078343","id":"PMC_25078343","title":"Molecular alterations of PIK3CA in uterine carcinosarcoma, clear cell, and serous tumors.","date":"2014","source":"International journal of gynecological cancer : official journal of the International Gynecological Cancer Society","url":"https://pubmed.ncbi.nlm.nih.gov/25078343","citation_count":22,"is_preprint":false},{"pmid":"36719480","id":"PMC_36719480","title":"Endothelial hyperactivation of mutant MAP3K3 induces cerebral cavernous malformation enhanced by PIK3CA GOF mutation.","date":"2023","source":"Angiogenesis","url":"https://pubmed.ncbi.nlm.nih.gov/36719480","citation_count":21,"is_preprint":false},{"pmid":"34655667","id":"PMC_34655667","title":"EZH2 inhibition confers PIK3CA-driven lung tumors enhanced sensitivity to PI3K inhibition.","date":"2021","source":"Cancer 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pathology","url":"https://pubmed.ncbi.nlm.nih.gov/25550888","citation_count":20,"is_preprint":false},{"pmid":"36635367","id":"PMC_36635367","title":"PIK3CA is recurrently mutated in canine mammary tumors, similarly to in human mammary neoplasia.","date":"2023","source":"Scientific reports","url":"https://pubmed.ncbi.nlm.nih.gov/36635367","citation_count":20,"is_preprint":false},{"pmid":"27401370","id":"PMC_27401370","title":"p53 Loses grip on PIK3CA expression leading to enhanced cell survival during platinum resistance.","date":"2016","source":"Molecular oncology","url":"https://pubmed.ncbi.nlm.nih.gov/27401370","citation_count":20,"is_preprint":false},{"pmid":"27296758","id":"PMC_27296758","title":"Triggering PIK3CA Mutations in PI3K/Akt/mTOR Axis: Exploration of Newer Inhibitors and Rational Preventive Strategies.","date":"2016","source":"Current pharmaceutical 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in squamous cell carcinoma: mutated PIK3CA as an example.","date":"2024","source":"Molecular biomedicine","url":"https://pubmed.ncbi.nlm.nih.gov/38616230","citation_count":18,"is_preprint":false},{"pmid":"38822093","id":"PMC_38822093","title":"PIK3CA mutations in endocrine-resistant breast cancer.","date":"2024","source":"Scientific reports","url":"https://pubmed.ncbi.nlm.nih.gov/38822093","citation_count":18,"is_preprint":false},{"pmid":"38842935","id":"PMC_38842935","title":"PIK3CA inhibition in models of proliferative glomerulonephritis and lupus nephritis.","date":"2024","source":"The Journal of clinical 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Three mechanistic groups were proposed based on structural mapping: C2 domain mutants increase positive surface charge potentially enhancing membrane recruitment; helical domain mutants affect protein-protein interaction surfaces; kinase domain mutants alter the activation loop hinge position.\",\n      \"method\": \"In vitro lipid kinase assay, oncogenic transformation assay (chicken embryo fibroblasts), Akt/TOR signaling assays, structural modeling with mutagenesis\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — in vitro enzymatic assay combined with cell-based transformation assay and structural analysis across 15 mutants with mutagenesis validation\",\n      \"pmids\": [\"17376864\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"Crystal structure of the p110α/p85α complex revealed that the majority of oncogenic PIK3CA mutations occur at interfaces between p110 domains and between p110 and p85 domains. At these positions, mutations disrupt inter-domain interactions causing conformational changes in the kinase domain that increase enzymatic activity. The structure also showed that membrane interaction is mediated by the iSH2 domain of p85.\",\n      \"method\": \"X-ray crystallography of p110α/p85α complex with structural mapping of cancer mutations\",\n      \"journal\": \"Cell cycle (Georgetown, Tex.)\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — crystal structure with functional interpretation of oncogenic mutations; foundational structural paper\",\n      \"pmids\": [\"18418043\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"Double PIK3CA mutations occurring in cis on the same allele (found in 12–15% of breast cancers) result in increased PI3K lipid kinase activity, enhanced downstream AKT signaling, increased cell proliferation, and tumor growth compared to single hotspot mutations. Biochemical mechanisms include increased disruption of p110α binding to the inhibitory subunit p85α (relieving catalytic inhibition) and increased p110α membrane lipid binding. Double mutations predict enhanced sensitivity to PI3Kα inhibitors.\",\n      \"method\": \"In vitro PI3K activity assay, cell proliferation assays, tumor growth models, biochemical p85α binding assays, cancer genome analysis\",\n      \"journal\": \"Science (New York, N.Y.)\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — multiple orthogonal biochemical and cellular methods in one study with mechanistic dissection of p85α binding and membrane lipid interaction\",\n      \"pmids\": [\"31699932\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"NEDD4L was identified as the E3 ubiquitin ligase that catalyzes PIK3CA polyubiquitination, leading to proteasome-dependent degradation of p110α. NEDD4L ubiquitinates both free and regulatory subunit-bound PIK3CA but does not ubiquitinate the regulatory subunit p85. Overexpression of NEDD4L accelerates PIK3CA turnover, while suppression of NEDD4L increases PIK3CA levels and paradoxically decreases AKT activation, indicating NEDD4L is required for maintenance of PI3K-AKT signaling.\",\n      \"method\": \"Co-immunoprecipitation, ubiquitination assay, proteasome inhibitor treatment, overexpression and knockdown of NEDD4L, Western blotting for AKT phosphorylation\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1/2 / Moderate — direct biochemical ubiquitination assay with Co-IP, gain and loss-of-function experiments, and functional readout of AKT signaling in single study\",\n      \"pmids\": [\"27339899\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"TRAF6 interacts with PIK3CA (p110α) and promotes its non-proteolytic polyubiquitination under serum stimulation. TRAF6 ubiquitinates both individual and regulatory subunit-bound PIK3CA but does not ubiquitinate the regulatory subunit. TRAF6 overexpression greatly enhances PI3K activation, leading to increased AKT phosphorylation and cell growth, establishing TRAF6 as a novel activating E3 ligase for PIK3CA.\",\n      \"method\": \"Co-immunoprecipitation, ubiquitination assay, TRAF6 overexpression with AKT phosphorylation readout, cell growth assay\",\n      \"journal\": \"FEBS letters\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal Co-IP and direct ubiquitination assay with functional downstream readout, single lab\",\n      \"pmids\": [\"29729098\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"PIK3CA mutant cancer cells exhibit increased reliance on glucose metabolism and specifically require the TCA cycle enzyme OGDH (2-oxoglutarate dehydrogenase). OGDH suppression in PIK3CA-mutant cells increases 2-oxoglutarate levels, leading to aspartate depletion, deregulation of the malate-aspartate shuttle, impaired cytoplasmic NAD+ regeneration, and a specific proliferative block due to inability to maintain NAD+/NADH homeostasis.\",\n      \"method\": \"Genome-scale RNAi loss-of-function screening in cancer cell lines, metabolic flux studies, OGDH knockdown, exogenous metabolite supplementation, NAD+/NADH measurement\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genome-scale functional screen combined with orthogonal metabolic studies and mechanistic rescue experiments\",\n      \"pmids\": [\"28396387\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"Expression of the Pik3ca H1047R hotspot mutation from its endogenous locus in mouse cells induces centrosome amplification through a pathway involving AKT, ROCK, and CDK2/Cyclin E-nucleophosmin. Mutant Pik3ca also increases cellular tolerance to spontaneous genome doubling in vitro and in mouse tissues.\",\n      \"method\": \"Conditional knock-in mouse model (endogenous locus), centrosome counting, pathway inhibitor experiments (AKT, ROCK, CDK2 inhibitors), genome ploidy analysis\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — endogenous knock-in model with pharmacological pathway dissection (AKT, ROCK, CDK2 inhibitors) establishing mechanistic pathway\",\n      \"pmids\": [\"29170395\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"PIK3CA H1047R expression in lineage-committed basal (Lgr5+) and luminal (K8+) mammary epithelial cells induces cell dedifferentiation into a multipotent stem-like state, demonstrated by in situ genetic lineage tracing and limiting dilution transplantation assays. The cell of origin of PIK3CA H1047R tumors dictates their malignancy.\",\n      \"method\": \"In situ genetic lineage tracing, limiting dilution transplantation, conditional PIK3CA H1047R knock-in mouse model\",\n      \"journal\": \"Nature\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — in vivo lineage tracing with functional transplantation assays in knock-in model, multiple orthogonal approaches\",\n      \"pmids\": [\"26266975\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"PIK3CA H1047R expression alone failed to promote lung tumor formation but dramatically enhanced tumorigenesis initiated by KRAS G12D in genetically engineered mouse models. Oncogenic cooperation was accompanied by PI3Kα-mediated regulation of c-MYC, GSK3β, p27KIP1, survivin, and RB pathway components, resulting in accelerated cell division, indicating that PI3'-lipid signaling remains rate-limiting for cell-cycle progression of early-stage KRAS-initiated lung cells.\",\n      \"method\": \"Genetically engineered mouse models (GEM), compound KRAS/PIK3CA knock-in, Western blotting for pathway components, cell cycle analysis\",\n      \"journal\": \"Cancer research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genetic epistasis in GEM models with mechanistic pathway analysis, multiple downstream targets identified\",\n      \"pmids\": [\"26567140\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"PIK3CA hotspot mutations (E542K, E545K, H1047R) cause chronic activation of AKT and dysregulation of angiogenic factors, and produce abnormal endothelial cell morphology when expressed in HUVECs. The p110α-specific inhibitor BYL719 restores all abnormal phenotypes in both PIK3CA-mutant and TEK-mutant HUVECs, demonstrating that PIK3CA and TEK mutations operate via the same PI3K-dependent pathogenic pathway in venous malformations.\",\n      \"method\": \"Expression of PIK3CA mutants in HUVECs, AKT phosphorylation assays, angiogenic factor measurement, morphology assays, pharmacological rescue with BYL719\",\n      \"journal\": \"American journal of human genetics\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — direct functional expression in primary endothelial cells with pharmacological rescue and multiple orthogonal phenotypic readouts\",\n      \"pmids\": [\"26637981\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"p85β (PIK3R2) dissociates from p110α helical domain mutant protein and translocates into the nucleus through a nuclear localization sequence (NLS). Nuclear p85β recruits deubiquitinase USP7 to stabilize EZH1 and EZH2, enhancing H3K27 trimethylation. Knockout of p85β or p85β NLS mutant reduces growth of PIK3CA helical domain mutant tumors. Combination of alpelisib and EZH inhibitor tazemetostat induced regression of PIK3CA helical domain mutant xenografts but not WT or kinase domain mutant tumors.\",\n      \"method\": \"Co-immunoprecipitation, nuclear fractionation, p85β NLS mutagenesis, USP7 interaction assay, EZH1/2 stability assay, H3K27me3 ChIP, xenograft models, genetic knockout\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — multiple orthogonal methods (Co-IP, fractionation, mutagenesis, in vivo models) establishing novel nuclear mechanism specific to helical domain mutations\",\n      \"pmids\": [\"35418124\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"p53 represses PIK3CA promoter activity through direct binding to p53 binding sequences in the PIK3CA promoter, and this repression depends on p53 phosphorylation at serine 46. In cisplatin-sensitive cells, cisplatin-induced p53 activation dynamically alters p53 occupancy at the PIK3CA promoter and attenuates PI3K/AKT signaling. In resistant cells, loss of p53 serine 46 phosphorylation abolishes PIK3CA promoter repression, resulting in sustained PIK3CA expression and cell survival.\",\n      \"method\": \"Promoter-luciferase reporter assay, chromatin immunoprecipitation (ChIP), p53 phosphorylation site mutagenesis (S46A), Western blotting, bioluminescent imaging in vivo\",\n      \"journal\": \"Molecular oncology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — ChIP and reporter assays with mutagenesis in single lab, multiple cell lines tested\",\n      \"pmids\": [\"27401370\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"Functional assessment of PIK3CA variants using high-throughput barcoded expression clones showed that PIK3CA variant oncogenic activity correlates imperfectly with mutation frequency in breast cancer. Mutations occurring above 5% frequency were significantly more oncogenic than wild-type in all assays, but lower frequency mutations varied from weak to strong oncogenicity. Proteomic profiling revealed variant-specific activation of PI3K signaling as well as MEK1/2 pathway activation depending on the specific PIK3CA mutation.\",\n      \"method\": \"High-throughput barcoded clone library, in vitro cell growth assay, soft agar transformation assay, in vivo tumor growth, proteomic profiling, therapeutic sensitivity assays\",\n      \"journal\": \"Cancer research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — multiple orthogonal functional assays across many variants with proteomics in a single systematic study\",\n      \"pmids\": [\"26627007\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"PIK3CA mutations can initiate pancreatic tumorigenesis: expression of constitutively active PIK3CA in mouse pancreas increased acinar-to-ductal metaplasia and pancreatic intraepithelial neoplasms (PanINs) as early as 10 days of age, with invasive pancreatic ductal adenocarcinoma by 20 days. These PIK3CA-mutant cancers showed phosphorylation of ERK1/2 in addition to PI3K pathway activation; ERK1/2 phosphorylation was diminished by dual PI3K/mTOR inhibition.\",\n      \"method\": \"Transgenic mouse models with pancreas-specific PIK3CA expression, histopathology, immunostaining, PI3K/mTOR inhibitor treatment\",\n      \"journal\": \"Oncogenesis\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — in vivo genetic model with mechanistic pathway analysis and pharmacological intervention\",\n      \"pmids\": [\"26436951\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"Growth of cerebral cavernous malformations (CCMs) requires both somatic gain-of-function mutations in PIK3CA and loss-of-function mutations in CCM complex genes (KRIT1/CCM2/PDCD10) in the same endothelial cells. Mouse models showed that PIK3CA gain-of-function augments mTOR signaling in endothelial cells, and that both CCM loss-of-function and increased KLF4 (downstream of MEKK3) augment mTOR signaling. mTORC1 inhibitor rapamycin effectively blocked CCM formation in mouse models.\",\n      \"method\": \"Mouse genetic models, somatic mutation analysis of human CCMs, mTOR pathway analysis, rapamycin treatment in vivo\",\n      \"journal\": \"Nature\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genetic epistasis in mouse models combined with human tissue mutation analysis and pharmacological rescue\",\n      \"pmids\": [\"33910229\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"Induction of PIK3CA H1047R in mouse mammary glands with constitutive activated Her2/Neu resulted in accelerated mammary tumorigenesis with enhanced metastatic potential. PIK3CA H1047R expression caused robust PI3K/AKT signaling activation but attenuated Her2/Her3 signaling. Tumors that escaped PI3K dependence after PIK3CA H1047R inactivation did so through compensatory ERK activation, which could be blocked by combined inhibition of Her2 and MEK.\",\n      \"method\": \"Compound transgenic mouse model (Her2 + inducible PIK3CA H1047R), deinduction of PIK3CA H1047R, Western blotting for pathway components, MEK and Her2 inhibitor treatment\",\n      \"journal\": \"Oncogene\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — in vivo compound genetic model with inducible system and pharmacological pathway dissection identifying compensatory ERK mechanism\",\n      \"pmids\": [\"26640141\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"In activated T and B lymphocytes, class I PI3K (indexed by PIP3) activity is spatially restricted to the microtubule-organizing center and then to one pole of the mitotic spindle, creating asymmetry. Asymmetric PI3K activity co-localizes with asymmetric distribution of antigen receptor components and glucose transporters (whose trafficking is PI3K-dependent). Perturbation of class I PI3K activity disrupts asymmetry of upstream antigen receptors and downstream glucose transporter trafficking, establishing PI3K as a core organizer of lymphocyte polarity and asymmetric cell division.\",\n      \"method\": \"PIP3 immunostaining in dividing lymphocytes, live imaging, PI3K inhibitor perturbation, glucose transporter trafficking assay\",\n      \"journal\": \"Cell reports\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct localization with functional perturbation in primary lymphocytes, single lab\",\n      \"pmids\": [\"29420173\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"PIK3CA E545K mutation negatively regulates SIRT4 expression through the epigenetic regulator EP300, independently of the canonical mTORC1 pathway. PIK3CA-E545K-induced SIRT4 downregulation promoted cell proliferation, migration, radiation-induced DNA repair, and reduced apoptosis in cervical cancer cells. SIRT4 modulates glutamine metabolism and cellular apoptosis by negatively regulating glutamate pyruvate transaminase GPT1. PI3K inhibitor BYL719 (but not mTOR inhibitors) had synergistic radiosensitizing effects by inhibiting glutamine metabolism.\",\n      \"method\": \"PIK3CA mutant cell line models, EP300 inhibition, SIRT4 overexpression/knockdown, GPT1 activity assay, glutamine metabolism measurement, radiosensitivity assay, in vivo xenograft\",\n      \"journal\": \"Cancer letters\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — mechanistic pathway dissection with multiple functional readouts, single lab, mTOR independence established pharmacologically\",\n      \"pmids\": [\"36646410\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"Overexpression of wild-type PIK3CA and its two common mutants K545E and H1047R significantly enhanced anchorage-independent growth activity and migration activity of immortalized human airway epithelial cells (16HBE14o-), with the effects of K545E and H1047R mutants being more pronounced than wild-type.\",\n      \"method\": \"Ectopic expression in human airway epithelial cell line, anchorage-independent growth assay (soft agar), migration assay\",\n      \"journal\": \"Pathology international\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct functional assays comparing wild-type vs mutant PIK3CA in human epithelial cells, single lab\",\n      \"pmids\": [\"17803655\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"Specific knockdown of mutant PIK3CA in urothelial carcinoma (UC) cell lines inhibited PI3K pathway activation, cell proliferation, migration, anchorage-independent growth, and in vivo tumor growth, establishing mutant PIK3CA as a potent oncogenic driver in UC. Sensitivity to the class I PI3K inhibitor GDC-0941 was dependent on hotspot PIK3CA mutation status; cells with co-occurring TSC1, PTEN, AKT1, or RAS mutations were less sensitive.\",\n      \"method\": \"Retrovirus-mediated shRNA knockdown of mutant PIK3CA, proliferation, migration, anchorage-independent growth assays, in vivo tumor growth, GDC-0941 sensitivity panel\",\n      \"journal\": \"BMC cancer\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — specific mutant knockdown with multiple phenotypic readouts and in vivo validation, single lab\",\n      \"pmids\": [\"27465249\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"PIK3CA isoform-specific knockdown experiments in multiple myeloma cells showed that PIK3CA (p110α) is of paramount importance for constitutive AKT activity in MM cells. Unlike knockdown of PIK3CB, PIK3CD, or PIK3CG, only PIK3CA knockdown or pharmacological PIK3CA inhibition with BYL-719 was sufficient to induce cell death in a sizeable subgroup of MM samples.\",\n      \"method\": \"Isoform-specific shRNA knockdown (PIK3CA, PIK3CB, PIK3CD, PIK3CG), isoform-specific inhibitors (BYL-719, TGX-221, CAL-101, CAY10505), AKT phosphorylation assay, cell viability assay\",\n      \"journal\": \"British journal of haematology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — isoform-specific genetic and pharmacological approaches across multiple MM samples, single lab\",\n      \"pmids\": [\"24766330\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"Germline PIK3CA mutations in Cowden syndrome patients result in significantly increased phospho-Thr308-AKT and increased cellular PIP3 levels compared to wild-type, directly demonstrating that these germline PIK3CA variants activate PI3K pathway signaling.\",\n      \"method\": \"Cell signaling assays (phospho-AKT, PIP3 measurement) in patient-derived cells with germline PIK3CA mutations\",\n      \"journal\": \"American journal of human genetics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Weak — direct functional signaling measurement in patient cells, single study, limited mechanistic detail in abstract\",\n      \"pmids\": [\"23246288\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"PIK3CA encodes p110α, the catalytic subunit of class IA PI3K, which functions as a lipid kinase generating PIP3 to activate AKT-mTOR signaling; oncogenic mutations (clustered in the helical domain, e.g., E542K/E545K, and kinase domain, e.g., H1047R) gain function by disrupting inhibitory p85α interactions and enhancing membrane lipid binding, leading to constitutive PI3K activation, and are regulated post-translationally by NEDD4L-mediated proteasomal degradation and TRAF6-mediated activating ubiquitination; helical domain mutations additionally trigger nuclear translocation of p85β to enhance EZH1/2-mediated H3K27 trimethylation, and mutant PIK3CA drives centrosome amplification via AKT-ROCK-CDK2/CyclinE-nucleophosmin, mammary cell dedifferentiation to multipotency, and metabolic reprogramming including glucose dependency and glutamine pathway alterations.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"PIK3CA encodes p110\\u03b1, the catalytic subunit of class IA PI3K, a lipid kinase whose activity drives AKT-TOR signaling and downstream control of proliferation, migration, and metabolism; cancer-derived mutations confer gain-of-function by constitutively activating this pathway and transforming cells [#0]. Structurally, oncogenic substitutions cluster at interfaces between p110 domains and between p110 and the regulatory subunit p85\\u03b1, where they disrupt inhibitory inter-domain contacts and provoke conformational changes in the kinase domain that elevate enzymatic output [#1]; the same logic extends to compound cis double mutations, which further relieve p85\\u03b1 inhibition and enhance membrane lipid binding to give supra-additive kinase activity and tumor growth [#2]. Beyond the canonical p110\\u03b1/p85\\u03b1/AKT axis, helical-domain mutants engage a distinct nuclear program in which dissociated p85\\u03b2 (PIK3R2) translocates to the nucleus, recruits the deubiquitinase USP7 to stabilize EZH1/EZH2, and enhances H3K27 trimethylation, a vulnerability exploited by combined PI3K\\u03b1 and EZH inhibition [#10]. p110\\u03b1 abundance and activity are tuned post-translationally by opposing E3 ligases: NEDD4L drives proteasomal degradation while also being required to sustain AKT signaling [#3], and TRAF6 mediates non-proteolytic activating ubiquitination upon serum stimulation [#4]; transcriptionally, p53 represses the PIK3CA promoter in a serine-46 phosphorylation-dependent manner [#11]. Mutant PIK3CA reprograms cell behavior and metabolism\\u2014inducing centrosome amplification through an AKT-ROCK-CDK2/Cyclin E-nucleophosmin pathway [#6], driving mammary epithelial dedifferentiation to a multipotent stem-like state [#7], and creating dependencies on glucose metabolism and the TCA enzyme OGDH for NAD+/NADH homeostasis [#5]. As a disease gene, PIK3CA is an oncogenic driver across breast, urothelial, pancreatic, lung, and myeloma contexts, frequently cooperating with KRAS or HER2 and converging on PI3K\\u03b1 inhibitors such as BYL719/alpelisib [#8, #15, #19, #20], and somatic or germline activating mutations underlie vascular malformations, cerebral cavernous malformations, and Cowden syndrome [#9, #14, #21].\"\n,\n  \"teleology\": [\n    {\n      \"year\": 2007,\n      \"claim\": \"Established that diverse cancer-derived PIK3CA mutations are bona fide gain-of-function alleles rather than passengers, defining PIK3CA as an oncogene acting through lipid kinase activity and AKT-TOR signaling.\",\n      \"evidence\": \"In vitro lipid kinase assays, chicken embryo fibroblast transformation, and AKT/TOR signaling readouts across 15 mutants with structural mapping\",\n      \"pmids\": [\"17376864\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Three mechanistic groups proposed from modeling rather than direct structural determination\", \"Did not resolve how each mutation class alters the enzyme at atomic resolution\"]\n    },\n    {\n      \"year\": 2007,\n      \"claim\": \"Confirmed in human epithelial cells that common mutants exceed wild-type in promoting transformed phenotypes, linking mutation status to oncogenic potency.\",\n      \"evidence\": \"Ectopic expression of WT, K545E, and H1047R in airway epithelial cells with soft-agar and migration assays\",\n      \"pmids\": [\"17803655\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Overexpression rather than endogenous expression\", \"No biochemical link to kinase output in these cells\"]\n    },\n    {\n      \"year\": 2008,\n      \"claim\": \"Provided the structural basis for activation by showing oncogenic mutations cluster at p110-p110 and p110-p85 interfaces, disrupting inhibitory contacts and reshaping the kinase domain.\",\n      \"evidence\": \"X-ray crystallography of the p110\\u03b1/p85\\u03b1 complex with mapping of cancer mutations\",\n      \"pmids\": [\"18418043\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Static structure does not capture membrane-bound active conformation\", \"Helical vs kinase domain mutant mechanisms not fully separated structurally\"]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"Demonstrated that germline PIK3CA variants activate the pathway in patient cells, extending oncogenic mechanisms to a heritable overgrowth syndrome.\",\n      \"evidence\": \"Phospho-Thr308-AKT and PIP3 measurements in Cowden syndrome patient-derived cells\",\n      \"pmids\": [\"23246288\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Limited mechanistic detail beyond signaling readouts\", \"Single study, small patient cohort\"]\n    },\n    {\n      \"year\": 2014,\n      \"claim\": \"Distinguished p110\\u03b1 from other class I isoforms as the non-redundant driver of constitutive AKT activity in a tumor context, supporting isoform-selective therapy.\",\n      \"evidence\": \"Isoform-specific shRNA and inhibitors (BYL-719 vs TGX-221, CAL-101, CAY10505) in multiple myeloma samples\",\n      \"pmids\": [\"24766330\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single lab\", \"Mechanism of isoform selectivity in MM not defined\"]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"Showed mutant PIK3CA reprograms cell identity by dedifferentiating committed mammary epithelial cells to a multipotent state, with cell-of-origin dictating tumor malignancy.\",\n      \"evidence\": \"In situ lineage tracing and limiting-dilution transplantation in a conditional H1047R knock-in mouse\",\n      \"pmids\": [\"26266975\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Molecular effectors of dedifferentiation not identified\", \"Generalizability beyond mammary lineage unknown\"]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"Established genetic cooperation with KRAS and HER2 and identified compensatory ERK signaling as an escape route, framing PI3K as rate-limiting in early oncogenesis.\",\n      \"evidence\": \"Compound GEM models (KRAS/PIK3CA; Her2/inducible H1047R) with pathway blotting and MEK/Her2 inhibitor experiments\",\n      \"pmids\": [\"26567140\", \"26640141\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Pancreatic, lung, and mammary contexts may differ in cooperating effectors\", \"ERK reactivation mechanism after PI3K loss not fully mapped\"]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"Demonstrated PIK3CA can initiate pancreatic tumorigenesis and that PI3K activation co-engages ERK signaling, broadening the oncogenic tissue spectrum.\",\n      \"evidence\": \"Pancreas-specific PIK3CA transgenic mice with histopathology and PI3K/mTOR inhibitor treatment\",\n      \"pmids\": [\"26436951\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Link between PI3K and ERK activation mechanistically indirect\", \"Constitutively active construct rather than endogenous hotspot allele\"]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"Systematically resolved variant-specific oncogenicity, showing potency only imperfectly tracks mutation frequency and that some variants additionally activate MEK1/2.\",\n      \"evidence\": \"High-throughput barcoded clone library with growth, soft-agar, in vivo, and proteomic profiling\",\n      \"pmids\": [\"26627007\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Mechanism of MEK co-activation by specific variants unresolved\", \"Overexpression system may not reflect endogenous levels\"]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"Linked PIK3CA mutations to vascular malformations and showed shared PI3K-dependent pathogenesis with TEK mutations, rescuable by PI3K\\u03b1 inhibition.\",\n      \"evidence\": \"PIK3CA and TEK mutant expression in HUVECs with AKT/angiogenic readouts and BYL719 rescue\",\n      \"pmids\": [\"26637981\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Endothelial-specific effectors downstream of AKT not detailed\", \"In vitro HUVEC model\"]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"Identified NEDD4L as the E3 ligase driving proteasomal turnover of p110\\u03b1 while paradoxically being required to sustain AKT signaling, revealing nuanced post-translational control.\",\n      \"evidence\": \"Co-IP, ubiquitination assays, proteasome inhibition, and NEDD4L gain/loss-of-function with AKT readout\",\n      \"pmids\": [\"27339899\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Mechanism of the paradoxical AKT requirement unexplained\", \"Ubiquitin chain linkage type not defined\"]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"Defined transcriptional control of PIK3CA by p53, where serine-46 phosphorylation enables promoter repression and its loss confers drug resistance via sustained PIK3CA expression.\",\n      \"evidence\": \"Promoter-luciferase reporters, ChIP, and S46A mutagenesis in cisplatin-sensitive vs resistant cells\",\n      \"pmids\": [\"27401370\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single lab\", \"Direct p53 binding site validation limited to reporter and ChIP\"]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"Confirmed mutant PIK3CA as a targetable driver in urothelial carcinoma, with inhibitor sensitivity gated by co-occurring pathway mutations.\",\n      \"evidence\": \"Mutant-specific shRNA knockdown and GDC-0941 sensitivity panel with in vivo tumor growth\",\n      \"pmids\": [\"27465249\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single lab\", \"Mechanism by which TSC1/PTEN/AKT1/RAS mutations reduce sensitivity not dissected\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Uncovered a metabolic dependency: PIK3CA-mutant cells require OGDH to maintain NAD+/NADH homeostasis via the malate-aspartate shuttle, exposing a metabolic vulnerability.\",\n      \"evidence\": \"Genome-scale RNAi screen, metabolic flux, OGDH knockdown, and metabolite rescue\",\n      \"pmids\": [\"28396387\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"How PI3K activation establishes OGDH dependency not fully mechanistic\", \"Generalizability across tumor types untested\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Showed endogenous H1047R drives centrosome amplification and tolerance to genome doubling through a defined AKT-ROCK-CDK2/Cyclin E-nucleophosmin pathway, linking PI3K to genome instability.\",\n      \"evidence\": \"Conditional endogenous-locus knock-in mouse with centrosome counting and AKT/ROCK/CDK2 inhibitor dissection\",\n      \"pmids\": [\"29170395\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Connection between PI3K and centrosome machinery indirect\", \"Contribution to tumor evolution in vivo not quantified\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Identified TRAF6 as an activating, non-proteolytic E3 ligase for p110\\u03b1 under serum stimulation, providing a positive post-translational regulatory arm opposing NEDD4L.\",\n      \"evidence\": \"Reciprocal Co-IP, ubiquitination assays, and TRAF6 overexpression with AKT and growth readouts\",\n      \"pmids\": [\"29729098\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single lab\", \"Ubiquitin chain topology and binding partner consequences not fully defined\", \"No loss-of-function validation in physiological setting\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Revealed a non-oncogenic physiological role: class I PI3K activity is spatially polarized to the MTOC and mitotic spindle pole to organize asymmetric lymphocyte division and receptor/glucose-transporter partitioning.\",\n      \"evidence\": \"PIP3 immunostaining, live imaging, and PI3K inhibitor perturbation in dividing T and B lymphocytes\",\n      \"pmids\": [\"29420173\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Isoform-specific contribution of p110\\u03b1 not isolated\", \"Mechanism establishing spatial restriction unknown\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Demonstrated that cis double mutations are functionally synergistic, deepening p85\\u03b1 release and membrane binding to amplify kinase output and predict enhanced inhibitor sensitivity.\",\n      \"evidence\": \"In vitro PI3K activity, proliferation/tumor models, p85\\u03b1 binding assays, and cancer genome analysis\",\n      \"pmids\": [\"31699932\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Structural basis of combined effects not crystallographically resolved\", \"Clinical predictiveness requires patient validation\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Showed that cerebral cavernous malformation growth requires combined PIK3CA gain-of-function and CCM-complex loss-of-function in the same endothelial cells, converging on mTOR and rescuable by rapamycin.\",\n      \"evidence\": \"Mouse genetic models, human CCM somatic mutation analysis, mTOR pathway analysis, rapamycin treatment\",\n      \"pmids\": [\"33910229\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Order and timing of the two mutational events in human lesions unclear\", \"Relative contributions of KLF4 vs PI3K to mTOR not quantified\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Defined a domain-specific noncanonical mechanism whereby helical-domain mutants release p85\\u03b2 to the nucleus to stabilize EZH1/2 via USP7 and boost H3K27me3, creating a mutation-class-specific therapeutic vulnerability.\",\n      \"evidence\": \"Co-IP, nuclear fractionation, NLS mutagenesis, USP7/EZH stability assays, H3K27me3 ChIP, and alpelisib+tazemetostat xenografts\",\n      \"pmids\": [\"35418124\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Genome-wide targets of nuclear p85\\u03b2/EZH program not catalogued\", \"Why only helical mutants release p85\\u03b2 structurally unresolved\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Identified an mTORC1-independent axis in which E545K suppresses SIRT4 via EP300 to reprogram glutamine metabolism and DNA repair, with PI3K\\u03b1 inhibition acting as a radiosensitizer.\",\n      \"evidence\": \"PIK3CA mutant cervical cancer models with EP300 inhibition, SIRT4/GPT1 manipulation, glutamine metabolism and radiosensitivity assays, and xenografts\",\n      \"pmids\": [\"36646410\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single lab\", \"How E545K signals to EP300 independently of mTORC1 not mechanistically resolved\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How the distinct mutation classes (C2, helical, kinase) selectively wire to canonical AKT-mTOR output versus noncanonical nuclear p85\\u03b2/EZH and mTOR-independent metabolic programs remains incompletely unified.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No single framework reconciles domain-specific canonical and noncanonical mechanisms\", \"Membrane-bound active-state structure of mutant complexes not resolved\", \"Integration of opposing NEDD4L/TRAF6 regulation in vivo unresolved\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0016740\", \"supporting_discovery_ids\": [0, 1, 2, 21]},\n      {\"term_id\": \"GO:0008289\", \"supporting_discovery_ids\": [1, 2, 21]},\n      {\"term_id\": \"GO:0016301\", \"supporting_discovery_ids\": [0]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005886\", \"supporting_discovery_ids\": [1, 2]},\n      {\"term_id\": \"GO:0005634\", \"supporting_discovery_ids\": [10]},\n      {\"term_id\": \"GO:0005815\", \"supporting_discovery_ids\": [16]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [0, 2, 21]},\n      {\"term_id\": \"R-HSA-1643685\", \"supporting_discovery_ids\": [9, 14, 19]},\n      {\"term_id\": \"R-HSA-1430728\", \"supporting_discovery_ids\": [5, 17]},\n      {\"term_id\": \"R-HSA-4839726\", \"supporting_discovery_ids\": [10]}\n    ],\n    \"complexes\": [\"class IA PI3K (p110\\u03b1/p85\\u03b1)\"],\n    \"partners\": [\"PIK3R1\", \"PIK3R2\", \"NEDD4L\", \"TRAF6\", \"USP7\", \"EZH2\", \"TP53\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":5,"faith_total":5,"faith_pct":100.0}}