{"gene":"LLGL2","run_date":"2026-06-10T02:59:50","timeline":{"discoveries":[{"year":2019,"finding":"LLGL2 forms a trimeric complex with the leucine transporter SLC7A5 and the membrane fusion regulator YKT6 to promote cell surface levels of SLC7A5 and leucine uptake, thereby supporting cell proliferation under nutrient stress in ER+ breast cancer cells.","method":"Co-immunoprecipitation (trimeric complex identification), cell surface assays, nutrient uptake assays, genetic loss-of-function","journal":"Nature","confidence":"High","confidence_rationale":"Tier 2 / Moderate — reciprocal Co-IP identifying trimeric complex, functional rescue experiments, and mechanistic follow-up with defined cellular phenotype in a single rigorous study","pmids":["30996345"],"is_preprint":false},{"year":2019,"finding":"Oestrogen receptor (ER) transcriptionally targets LLGL2 expression in ER+ breast cancer cells.","method":"Gene expression analysis upon ER modulation; endocrine treatment resistance experiments","journal":"Nature","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — functional link established in single study but method detail limited in abstract","pmids":["30996345"],"is_preprint":false},{"year":2011,"finding":"Murine Llgl2 is required for cell polarization and polarized invasion of trophoblasts during placental branching morphogenesis, as demonstrated by Llgl2 knockout mice showing defective placental development.","method":"Knockout mouse generation (Llgl2−/− mice), histological and cell biological analysis of placental trophoblasts","journal":"Molecular and cellular biology","confidence":"High","confidence_rationale":"Tier 2 / Strong — clean in vivo knockout with defined cellular phenotype (polarized invasion) and developmental readout","pmids":["21606200"],"is_preprint":false},{"year":2012,"finding":"Snail directly binds E-boxes in the LLGL2/Hugl-2 promoter and represses its expression; removal of these E-boxes releases Hugl-2 from Snail-mediated repression. Conversely, re-expression of Hugl-2 in cells with constitutive Snail reduces nuclear localization of Snail and suppresses Snail binding to its target promoters, reversing EMT.","method":"Promoter reporter assays, E-box deletion mutants, ChIP, nuclear localization analysis, gain-of-function rescue experiments","journal":"Oncogene","confidence":"High","confidence_rationale":"Tier 2 / Moderate — ChIP and promoter mutagenesis in single lab with multiple orthogonal methods establishing bidirectional regulatory relationship","pmids":["22580609"],"is_preprint":false},{"year":2007,"finding":"The LLGL2/Hugl-2 promoter contains a GC-rich region bound by Sp-1 transcription factors that drives basal expression; EGF signaling suppresses Hugl-2 expression in primary hepatocytes.","method":"Luciferase reporter assays with promoter truncations, mithramycin A treatment (Sp-1 inhibitor), EGF treatment of primary hepatocytes","journal":"Biochemical and biophysical research communications","confidence":"Medium","confidence_rationale":"Tier 2 / Weak — functional promoter dissection with pharmacological inhibition, single lab","pmids":["18155665"],"is_preprint":false},{"year":2023,"finding":"LLGL2 interacts with ACTN1 (alpha-actinin-1) and alters its intracellular localization and function without changing ACTN1 protein or mRNA levels, thereby impairing actin filament bundling and inhibiting cytoskeletal remodeling-dependent invasion and metastasis of ovarian cancer cells.","method":"Immunoprecipitation combined with mass spectrometry, localization analysis, in vitro invasion/migration assays, in vivo metastasis model","journal":"Cancers","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — IP-MS identifying binding partner plus functional localization and phenotypic validation, single lab","pmids":["38136424"],"is_preprint":false},{"year":2025,"finding":"MDM2 acts as an upstream E3 ubiquitin ligase that promotes LLGL2 degradation via the proteasomal pathway. LLGL2 loss in turn suppresses CRC progression by destabilizing THBS3 mRNA through interaction with the CCR4-NOT complex subunit CNOT1, thereby inactivating the PI3K-Akt pathway.","method":"RNA immunoprecipitation sequencing, shotgun mass spectrometry (identifying CNOT1 interaction), RNA sequencing, proteasome inhibition assays","journal":"Advanced science","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — multiple orthogonal methods (RIP-seq, MS, RNA-seq) in single study identifying upstream ubiquitin-mediated degradation and downstream mRNA stability mechanism","pmids":["40619612"],"is_preprint":false},{"year":2022,"finding":"Knockdown of LLGL2 suppresses estradiol-induced proliferation of BPH-1 prostate cells and upregulates autophagosome formation markers (LC3-B, ATG7, p-beclin), while LLGL2 overexpression has the opposite effect, indicating that LLGL2 promotes cell proliferation by suppressing autophagosome formation.","method":"siRNA knockdown, plasmid overexpression, Western blot for autophagy markers, proliferation assays","journal":"Biomedicines","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — gain- and loss-of-function with consistent results across two orthogonal approaches, single lab","pmids":["36009528"],"is_preprint":false},{"year":2024,"finding":"LLGL2 knockdown in prostate cancer PC3 cells induces autophagy flux by upregulating Vps34 and ATG14L, and this autophagy induction in turn suppresses EMT (upregulating E-cadherin, downregulating fibronectin and α-SMA). Rapamycin-induced autophagy phenocopies LLGL2 knockdown, and 3-methyladenine (autophagy inhibitor) reverses these effects.","method":"siRNA knockdown, pharmacological autophagy induction/inhibition (rapamycin, 3-MA), shLLGL2 xenograft mouse model, Western blot for EMT and autophagy markers","journal":"Biological research","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — in vitro and in vivo rescue experiments with pharmacological epistasis linking LLGL2 to autophagy-EMT axis, single lab","pmids":["38720397"],"is_preprint":false},{"year":2021,"finding":"LLGL2 promotes hepatocellular carcinoma cell proliferation, migration, and invasion by promoting calcium ion influx and activating the PI3K/AKT signaling pathway.","method":"In vitro functional assays, calcium influx measurements, PI3K/AKT pathway analysis, in vivo tumor models","journal":"Frontiers in oncology","confidence":"Low","confidence_rationale":"Tier 3 / Weak — single lab, limited mechanistic detail in abstract for the calcium-PI3K link","pmids":["34178676"],"is_preprint":false},{"year":2023,"finding":"Combined ablation of Llgl1 and Llgl2 in mouse skin epidermis causes activation of aPKC and upregulation of NF-κB signaling, and cooperates with Trp53 loss to drive squamous cell carcinoma development.","method":"Conditional double knockout mice (K14-Cre; Llgl1/2 cKO), genetic epistasis with Trp53 cKO, signaling pathway analysis","journal":"bioRxiv","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — in vivo genetic epistasis with clean phenotypic readout, but preprint and combined Llgl1/2 knockout limits specificity to LLGL2 alone","pmids":["36945368"],"is_preprint":true},{"year":2024,"finding":"LLGL2 silencing in oral squamous cell carcinoma Cal-27 cells upregulates occludin expression and increases cancer cell invasion and migration, placing LLGL2 upstream of occludin in the regulation of invasive behavior.","method":"siRNA knockdown, invasion and migration assays, Western blot for occludin","journal":"Acta biochimica et biophysica Sinica","confidence":"Low","confidence_rationale":"Tier 3 / Weak — single lab, single method set, limited mechanistic validation of the LLGL2-occludin link","pmids":["39394821"],"is_preprint":false},{"year":2024,"finding":"LLGL2 overexpression in endometrial cancer cells activates the Hedgehog signaling pathway (upregulating SHH, PTCH1, SMO, GLI1), and this effect is reversed by the Hedgehog inhibitor JK184, placing LLGL2 upstream of Hedgehog pathway transduction.","method":"Overexpression and knockdown experiments, Western blot and RT-qPCR for Hedgehog pathway components, pharmacological inhibition with JK184, xenograft mouse model","journal":"Cellular signalling","confidence":"Low","confidence_rationale":"Tier 3 / Weak — single lab, pathway placement based on expression changes with pharmacological epistasis but no direct molecular interaction established","pmids":["39647764"],"is_preprint":false}],"current_model":"LLGL2 is a scaffolding polarity protein that operates in multiple contexts: it forms a trimeric complex with SLC7A5 and YKT6 to regulate leucine transporter surface levels and promote nutrient uptake; it is transcriptionally repressed by Snail (via E-box binding) while reciprocally reducing Snail nuclear localization; it undergoes MDM2-mediated ubiquitin-proteasomal degradation and, when present, stabilizes THBS3 mRNA through CNOT1 interaction to suppress PI3K-Akt signaling; it interacts with ACTN1 to alter cytoskeletal remodeling and inhibit cell invasion; it suppresses autophagosome formation (via Vps34/ATG14L) to modulate EMT; and in vivo loss of Llgl1/2 activates aPKC and NF-κB to cooperate with p53 loss in driving squamous cell carcinoma."},"narrative":{"mechanistic_narrative":"LLGL2 is a scaffolding polarity protein that links cell-surface nutrient transport, cytoskeletal organization, and epithelial polarity to the control of proliferation and invasion in epithelial tissues [PMID:30996345, PMID:21606200]. As a polarity determinant, murine Llgl2 is required for trophoblast cell polarization and polarized invasion during placental branching morphogenesis [PMID:21606200]. In ER+ breast cancer it assembles into a trimeric complex with the leucine transporter SLC7A5 and the membrane-fusion regulator YKT6 to raise SLC7A5 cell-surface levels and leucine uptake, sustaining proliferation under nutrient stress, and its expression is driven by oestrogen receptor signaling [PMID:30996345]. LLGL2 expression is itself controlled at the promoter level by Sp-1-dependent basal transcription and by Snail, which binds E-boxes to repress LLGL2; reciprocally, restored LLGL2 reduces Snail nuclear localization and reverses EMT [PMID:22580609, PMID:18155665]. LLGL2 protein is targeted for proteasomal degradation by the E3 ligase MDM2, and when present it engages the CCR4-NOT subunit CNOT1 to stabilize THBS3 mRNA and modulate PI3K-Akt signaling [PMID:40619612]. Through interaction with ACTN1 it redirects alpha-actinin localization to impair actin filament bundling and cytoskeletal-remodeling-dependent invasion [PMID:38136424], and it restrains autophagosome formation via Vps34/ATG14L, an axis that in turn shapes EMT and proliferation [PMID:36009528, PMID:38720397].","teleology":[{"year":2011,"claim":"Establishing whether mammalian Llgl2 has a non-redundant role in vivo, the knockout defined it as a polarity factor required for directed cell behavior during development.","evidence":"Llgl2-knockout mice with histological and cell-biological analysis of placental trophoblasts","pmids":["21606200"],"confidence":"High","gaps":["Molecular partners mediating polarized trophoblast invasion not defined","Did not address LLGL2 role outside placenta"]},{"year":2007,"claim":"Addressing how LLGL2 transcription is set, promoter dissection identified Sp-1 as a driver of basal expression and EGF signaling as a repressive input.","evidence":"Luciferase reporter truncations, mithramycin A (Sp-1 inhibition), and EGF treatment of primary hepatocytes","pmids":["18155665"],"confidence":"Medium","gaps":["EGF-to-promoter signaling intermediates unmapped","No protein-level consequence demonstrated"]},{"year":2012,"claim":"To connect LLGL2 to EMT control, work showed a bidirectional antagonism with Snail at the transcriptional level.","evidence":"Promoter reporter assays, E-box deletion mutants, ChIP, nuclear localization analysis, and gain-of-function rescue","pmids":["22580609"],"confidence":"High","gaps":["Mechanism by which LLGL2 reduces Snail nuclear localization unresolved","No direct LLGL2-Snail physical interaction shown"]},{"year":2019,"claim":"Defining a concrete molecular function, LLGL2 was shown to scaffold a transporter complex coupling nutrient uptake to proliferation, downstream of ER.","evidence":"Reciprocal Co-IP identifying an SLC7A5-YKT6-LLGL2 trimer, surface and uptake assays, and ER-modulation expression analysis in ER+ breast cancer cells","pmids":["30996345"],"confidence":"High","gaps":["Structural basis of trimer assembly unknown","Whether YKT6/SLC7A5 partnership operates outside breast cancer untested"]},{"year":2021,"claim":"Testing a downstream signaling role, LLGL2 was linked to calcium influx and PI3K/AKT activation in hepatocellular carcinoma.","evidence":"In vitro functional assays, calcium influx measurements, and in vivo tumor models","pmids":["34178676"],"confidence":"Low","gaps":["Mechanistic link between LLGL2 and calcium influx not defined","Single lab, limited mechanistic detail"]},{"year":2022,"claim":"Probing how LLGL2 promotes proliferation, gain/loss-of-function placed it as a suppressor of autophagosome formation in prostate cells.","evidence":"siRNA knockdown, overexpression, and Western blot for autophagy markers with proliferation assays","pmids":["36009528"],"confidence":"Medium","gaps":["Direct molecular target on the autophagy machinery not identified","Single context"]},{"year":2023,"claim":"Identifying a cytoskeletal effector, IP-MS revealed ACTN1 as a partner whose localization LLGL2 redirects to suppress invasion.","evidence":"IP-MS, localization analysis, in vitro invasion/migration assays, and an in vivo metastasis model in ovarian cancer cells","pmids":["38136424"],"confidence":"Medium","gaps":["Binding interface and stoichiometry undefined","How LLGL2 alters ACTN1 localization mechanistically unknown"]},{"year":2023,"claim":"Assessing tumor-suppressive polarity function in vivo, combined Llgl1/2 loss was shown to activate aPKC and NF-κB and cooperate with p53 loss in driving squamous cell carcinoma.","evidence":"Conditional double-knockout mice with Trp53 epistasis and signaling analysis (preprint)","pmids":["36945368"],"confidence":"Medium","gaps":["Cannot resolve LLGL2-specific contribution from LLGL1","Preprint, not peer-reviewed"]},{"year":2024,"claim":"Extending the autophagy link, LLGL2 knockdown was shown to induce Vps34/ATG14L-dependent autophagy flux that suppresses EMT.","evidence":"siRNA knockdown, rapamycin/3-MA pharmacological epistasis, and shLLGL2 xenografts in prostate cancer cells","pmids":["38720397"],"confidence":"Medium","gaps":["Whether LLGL2 acts directly on Vps34/ATG14L untested","Connection to the breast-cancer transporter function unexplored"]},{"year":2024,"claim":"Two studies placed LLGL2 upstream of additional invasion/signaling outputs (occludin regulation; Hedgehog pathway activation).","evidence":"siRNA knockdown with invasion assays (OSCC) and overexpression/knockdown with JK184 pharmacological epistasis and xenografts (endometrial cancer)","pmids":["39394821","39647764"],"confidence":"Low","gaps":["No direct molecular interactions established for either axis","Pathway placements rest on expression changes alone"]},{"year":2025,"claim":"Defining upstream and downstream regulation of LLGL2 levels, MDM2 was identified as its E3 ligase and CNOT1-mediated THBS3 mRNA stabilization as a downstream effector tied to PI3K-Akt.","evidence":"RIP-seq, shotgun MS (CNOT1), RNA-seq, and proteasome inhibition in colorectal cancer","pmids":["40619612"],"confidence":"Medium","gaps":["MDM2 ubiquitination site on LLGL2 not mapped","Whether LLGL2 directly binds THBS3 mRNA versus via CNOT1 unresolved"]},{"year":null,"claim":"How LLGL2's distinct activities — transporter scaffolding, ACTN1-cytoskeletal control, autophagy suppression, and mRNA stabilization — are coordinated within a single polarity-dependent program remains unresolved.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No unifying biochemical mechanism integrating the multiple reported partners","Context-dependence of tumor-suppressive versus tumor-promoting roles unexplained","No structural model of LLGL2 in any complex"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0060090","term_label":"molecular adaptor activity","supporting_discovery_ids":[0,5]},{"term_id":"GO:0008092","term_label":"cytoskeletal protein binding","supporting_discovery_ids":[5]},{"term_id":"GO:0003723","term_label":"RNA binding","supporting_discovery_ids":[6]}],"localization":[{"term_id":"GO:0005886","term_label":"plasma membrane","supporting_discovery_ids":[0]},{"term_id":"GO:0005856","term_label":"cytoskeleton","supporting_discovery_ids":[5]}],"pathway":[{"term_id":"R-HSA-9612973","term_label":"Autophagy","supporting_discovery_ids":[7,8]},{"term_id":"R-HSA-162582","term_label":"Signal Transduction","supporting_discovery_ids":[6]},{"term_id":"R-HSA-382551","term_label":"Transport of small molecules","supporting_discovery_ids":[0]}],"complexes":["SLC7A5-YKT6-LLGL2 trimeric complex"],"partners":["SLC7A5","YKT6","ACTN1","CNOT1","MDM2"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q6P1M3","full_name":"LLGL scribble cell polarity complex component 2","aliases":["HGL","Lethal(2) giant larvae protein homolog 2"],"length_aa":1020,"mass_kda":113.4,"function":"Part of a complex with GPSM2/LGN, PRKCI/aPKC and PARD6B/Par-6, which may ensure the correct organization and orientation of bipolar spindles for normal cell division. This complex plays roles in the initial phase of the establishment of epithelial cell polarity","subcellular_location":"Cytoplasm","url":"https://www.uniprot.org/uniprotkb/Q6P1M3/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/LLGL2","classification":"Not Classified","n_dependent_lines":22,"n_total_lines":1208,"dependency_fraction":0.018211920529801324},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[{"gene":"PRKCI","stoichiometry":0.2}],"url":"https://opencell.sf.czbiohub.org/search/LLGL2","total_profiled":1310},"omim":[{"mim_id":"620915","title":"MYOSIN XVB; MYO15B","url":"https://www.omim.org/entry/620915"},{"mim_id":"618483","title":"LLGL SCRIBBLE CELL POLARITY COMPLEX COMPONENT 2; LLGL2","url":"https://www.omim.org/entry/618483"},{"mim_id":"600182","title":"SOLUTE CARRIER FAMILY 7 (CATIONIC AMINO ACID TRANSPORTER, y+ SYSTEM), MEMBER 5; SLC7A5","url":"https://www.omim.org/entry/600182"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Supported","locations":[{"location":"Cytosol","reliability":"Supported"},{"location":"Vesicles","reliability":"Additional"}],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in many","driving_tissues":[],"url":"https://www.proteinatlas.org/search/LLGL2"},"hgnc":{"alias_symbol":["HGL","Hugl-2"],"prev_symbol":[]},"alphafold":{"accession":"Q6P1M3","domains":[{"cath_id":"2.130.10.10","chopping":"231-382","consensus_level":"medium","plddt":95.2026,"start":231,"end":382},{"cath_id":"-","chopping":"386-412_437-474_504-629","consensus_level":"medium","plddt":95.303,"start":386,"end":629},{"cath_id":"-","chopping":"707-834","consensus_level":"medium","plddt":95.1598,"start":707,"end":834}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q6P1M3","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q6P1M3-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q6P1M3-F1-predicted_aligned_error_v6.png","plddt_mean":84.88},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=LLGL2","jax_strain_url":"https://www.jax.org/strain/search?query=LLGL2"},"sequence":{"accession":"Q6P1M3","fasta_url":"https://rest.uniprot.org/uniprotkb/Q6P1M3.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q6P1M3/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q6P1M3"}},"corpus_meta":[{"pmid":"30996345","id":"PMC_30996345","title":"LLGL2 rescues nutrient stress by promoting leucine uptake in ER+ breast cancer.","date":"2019","source":"Nature","url":"https://pubmed.ncbi.nlm.nih.gov/30996345","citation_count":135,"is_preprint":false},{"pmid":"21606200","id":"PMC_21606200","title":"Mammalian Llgl2 is necessary for proper branching morphogenesis during placental development.","date":"2011","source":"Molecular and cellular biology","url":"https://pubmed.ncbi.nlm.nih.gov/21606200","citation_count":34,"is_preprint":false},{"pmid":"22580609","id":"PMC_22580609","title":"The human Lgl polarity gene, Hugl-2, induces MET and suppresses Snail tumorigenesis.","date":"2012","source":"Oncogene","url":"https://pubmed.ncbi.nlm.nih.gov/22580609","citation_count":31,"is_preprint":false},{"pmid":"18155665","id":"PMC_18155665","title":"Cloning and characterization of the promoter of Hugl-2, the human homologue of Drosophila lethal giant larvae (lgl) polarity gene.","date":"2007","source":"Biochemical and biophysical research communications","url":"https://pubmed.ncbi.nlm.nih.gov/18155665","citation_count":15,"is_preprint":false},{"pmid":"36131361","id":"PMC_36131361","title":"SOX2 inhibits LLGL2 polarity protein in esophageal squamous cell carcinoma via miRNA-142-3p.","date":"2022","source":"Cancer biology & therapy","url":"https://pubmed.ncbi.nlm.nih.gov/36131361","citation_count":11,"is_preprint":false},{"pmid":"34178676","id":"PMC_34178676","title":"LLGL2 Increases Ca2+ Influx and Exerts Oncogenic Activities via PI3K/AKT Signaling Pathway in Hepatocellular Carcinoma.","date":"2021","source":"Frontiers in oncology","url":"https://pubmed.ncbi.nlm.nih.gov/34178676","citation_count":10,"is_preprint":false},{"pmid":"38136424","id":"PMC_38136424","title":"LLGL2 Inhibits Ovarian Cancer Metastasis by Regulating Cytoskeleton Remodeling via ACTN1.","date":"2023","source":"Cancers","url":"https://pubmed.ncbi.nlm.nih.gov/38136424","citation_count":8,"is_preprint":false},{"pmid":"40619612","id":"PMC_40619612","title":"Ubiquitination-Dependent LLGL2 Degradation Drives Colorectal Cancer Progression via THBS3 mRNA Stabilization.","date":"2025","source":"Advanced science (Weinheim, Baden-Wurttemberg, Germany)","url":"https://pubmed.ncbi.nlm.nih.gov/40619612","citation_count":3,"is_preprint":false},{"pmid":"39054612","id":"PMC_39054612","title":"Identification of MORN3 and LLGL2 as novel diagnostic biomarkers for latent tuberculosis infection using machine learning strategies and experimental verification.","date":"2024","source":"Annals of medicine","url":"https://pubmed.ncbi.nlm.nih.gov/39054612","citation_count":3,"is_preprint":false},{"pmid":"36009528","id":"PMC_36009528","title":"Silencing of LLGL2 Suppresses the Estradiol-Induced BPH-1 Cell Proliferation through the Regulation of Autophagy.","date":"2022","source":"Biomedicines","url":"https://pubmed.ncbi.nlm.nih.gov/36009528","citation_count":3,"is_preprint":false},{"pmid":"36945368","id":"PMC_36945368","title":"Lethal giant larvae gene family ( Llgl1 and Llgl2 ) functions as a tumor suppressor in mouse skin epidermis.","date":"2023","source":"bioRxiv : the preprint server for biology","url":"https://pubmed.ncbi.nlm.nih.gov/36945368","citation_count":2,"is_preprint":false},{"pmid":"38720397","id":"PMC_38720397","title":"Novel role of LLGL2 silencing in autophagy: reversing epithelial-mesenchymal transition in prostate cancer.","date":"2024","source":"Biological research","url":"https://pubmed.ncbi.nlm.nih.gov/38720397","citation_count":2,"is_preprint":false},{"pmid":"39394821","id":"PMC_39394821","title":"Collagen prolyl 4-hydroxylase subunit α member-induced head and neck squamous cell carcinoma aggressiveness is antagonized by LLGL2 via reduced expression of occludin.","date":"2024","source":"Acta biochimica et biophysica Sinica","url":"https://pubmed.ncbi.nlm.nih.gov/39394821","citation_count":1,"is_preprint":false},{"pmid":"39647764","id":"PMC_39647764","title":"LLGL2 targets the Hedgehog signaling pathway to influence malignant progression of endometrial cancer.","date":"2024","source":"Cellular signalling","url":"https://pubmed.ncbi.nlm.nih.gov/39647764","citation_count":1,"is_preprint":false},{"pmid":"37805392","id":"PMC_37805392","title":"[Differential expression of LLGL2 in prostate ductal adenocarcinoma and acinar adenocarcinoma and its significance].","date":"2023","source":"Zhonghua bing li xue za zhi = Chinese journal of pathology","url":"https://pubmed.ncbi.nlm.nih.gov/37805392","citation_count":0,"is_preprint":false},{"pmid":"28274313","id":"PMC_28274313","title":"[Establishment of esophageal squamous carcinoma cell lines stably over-expressing LLGL2].","date":"2017","source":"Xi bao yu fen zi mian yi xue za zhi = Chinese journal of cellular and molecular immunology","url":"https://pubmed.ncbi.nlm.nih.gov/28274313","citation_count":0,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":10218,"output_tokens":2998,"usd":0.037812,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":10424,"output_tokens":3539,"usd":0.070297,"stage2_stop_reason":"end_turn"},"total_usd":0.108109,"stage1_batch_id":"msgbatch_01BbTCMyrRPyhtEq6b1MdwCN","stage2_batch_id":"msgbatch_011dEed5bbxYvTAaQWKJevxu","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2019,\n      \"finding\": \"LLGL2 forms a trimeric complex with the leucine transporter SLC7A5 and the membrane fusion regulator YKT6 to promote cell surface levels of SLC7A5 and leucine uptake, thereby supporting cell proliferation under nutrient stress in ER+ breast cancer cells.\",\n      \"method\": \"Co-immunoprecipitation (trimeric complex identification), cell surface assays, nutrient uptake assays, genetic loss-of-function\",\n      \"journal\": \"Nature\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal Co-IP identifying trimeric complex, functional rescue experiments, and mechanistic follow-up with defined cellular phenotype in a single rigorous study\",\n      \"pmids\": [\"30996345\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"Oestrogen receptor (ER) transcriptionally targets LLGL2 expression in ER+ breast cancer cells.\",\n      \"method\": \"Gene expression analysis upon ER modulation; endocrine treatment resistance experiments\",\n      \"journal\": \"Nature\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — functional link established in single study but method detail limited in abstract\",\n      \"pmids\": [\"30996345\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"Murine Llgl2 is required for cell polarization and polarized invasion of trophoblasts during placental branching morphogenesis, as demonstrated by Llgl2 knockout mice showing defective placental development.\",\n      \"method\": \"Knockout mouse generation (Llgl2−/− mice), histological and cell biological analysis of placental trophoblasts\",\n      \"journal\": \"Molecular and cellular biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — clean in vivo knockout with defined cellular phenotype (polarized invasion) and developmental readout\",\n      \"pmids\": [\"21606200\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"Snail directly binds E-boxes in the LLGL2/Hugl-2 promoter and represses its expression; removal of these E-boxes releases Hugl-2 from Snail-mediated repression. Conversely, re-expression of Hugl-2 in cells with constitutive Snail reduces nuclear localization of Snail and suppresses Snail binding to its target promoters, reversing EMT.\",\n      \"method\": \"Promoter reporter assays, E-box deletion mutants, ChIP, nuclear localization analysis, gain-of-function rescue experiments\",\n      \"journal\": \"Oncogene\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — ChIP and promoter mutagenesis in single lab with multiple orthogonal methods establishing bidirectional regulatory relationship\",\n      \"pmids\": [\"22580609\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"The LLGL2/Hugl-2 promoter contains a GC-rich region bound by Sp-1 transcription factors that drives basal expression; EGF signaling suppresses Hugl-2 expression in primary hepatocytes.\",\n      \"method\": \"Luciferase reporter assays with promoter truncations, mithramycin A treatment (Sp-1 inhibitor), EGF treatment of primary hepatocytes\",\n      \"journal\": \"Biochemical and biophysical research communications\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Weak — functional promoter dissection with pharmacological inhibition, single lab\",\n      \"pmids\": [\"18155665\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"LLGL2 interacts with ACTN1 (alpha-actinin-1) and alters its intracellular localization and function without changing ACTN1 protein or mRNA levels, thereby impairing actin filament bundling and inhibiting cytoskeletal remodeling-dependent invasion and metastasis of ovarian cancer cells.\",\n      \"method\": \"Immunoprecipitation combined with mass spectrometry, localization analysis, in vitro invasion/migration assays, in vivo metastasis model\",\n      \"journal\": \"Cancers\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — IP-MS identifying binding partner plus functional localization and phenotypic validation, single lab\",\n      \"pmids\": [\"38136424\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"MDM2 acts as an upstream E3 ubiquitin ligase that promotes LLGL2 degradation via the proteasomal pathway. LLGL2 loss in turn suppresses CRC progression by destabilizing THBS3 mRNA through interaction with the CCR4-NOT complex subunit CNOT1, thereby inactivating the PI3K-Akt pathway.\",\n      \"method\": \"RNA immunoprecipitation sequencing, shotgun mass spectrometry (identifying CNOT1 interaction), RNA sequencing, proteasome inhibition assays\",\n      \"journal\": \"Advanced science\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple orthogonal methods (RIP-seq, MS, RNA-seq) in single study identifying upstream ubiquitin-mediated degradation and downstream mRNA stability mechanism\",\n      \"pmids\": [\"40619612\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"Knockdown of LLGL2 suppresses estradiol-induced proliferation of BPH-1 prostate cells and upregulates autophagosome formation markers (LC3-B, ATG7, p-beclin), while LLGL2 overexpression has the opposite effect, indicating that LLGL2 promotes cell proliferation by suppressing autophagosome formation.\",\n      \"method\": \"siRNA knockdown, plasmid overexpression, Western blot for autophagy markers, proliferation assays\",\n      \"journal\": \"Biomedicines\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — gain- and loss-of-function with consistent results across two orthogonal approaches, single lab\",\n      \"pmids\": [\"36009528\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"LLGL2 knockdown in prostate cancer PC3 cells induces autophagy flux by upregulating Vps34 and ATG14L, and this autophagy induction in turn suppresses EMT (upregulating E-cadherin, downregulating fibronectin and α-SMA). Rapamycin-induced autophagy phenocopies LLGL2 knockdown, and 3-methyladenine (autophagy inhibitor) reverses these effects.\",\n      \"method\": \"siRNA knockdown, pharmacological autophagy induction/inhibition (rapamycin, 3-MA), shLLGL2 xenograft mouse model, Western blot for EMT and autophagy markers\",\n      \"journal\": \"Biological research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — in vitro and in vivo rescue experiments with pharmacological epistasis linking LLGL2 to autophagy-EMT axis, single lab\",\n      \"pmids\": [\"38720397\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"LLGL2 promotes hepatocellular carcinoma cell proliferation, migration, and invasion by promoting calcium ion influx and activating the PI3K/AKT signaling pathway.\",\n      \"method\": \"In vitro functional assays, calcium influx measurements, PI3K/AKT pathway analysis, in vivo tumor models\",\n      \"journal\": \"Frontiers in oncology\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — single lab, limited mechanistic detail in abstract for the calcium-PI3K link\",\n      \"pmids\": [\"34178676\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"Combined ablation of Llgl1 and Llgl2 in mouse skin epidermis causes activation of aPKC and upregulation of NF-κB signaling, and cooperates with Trp53 loss to drive squamous cell carcinoma development.\",\n      \"method\": \"Conditional double knockout mice (K14-Cre; Llgl1/2 cKO), genetic epistasis with Trp53 cKO, signaling pathway analysis\",\n      \"journal\": \"bioRxiv\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — in vivo genetic epistasis with clean phenotypic readout, but preprint and combined Llgl1/2 knockout limits specificity to LLGL2 alone\",\n      \"pmids\": [\"36945368\"],\n      \"is_preprint\": true\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"LLGL2 silencing in oral squamous cell carcinoma Cal-27 cells upregulates occludin expression and increases cancer cell invasion and migration, placing LLGL2 upstream of occludin in the regulation of invasive behavior.\",\n      \"method\": \"siRNA knockdown, invasion and migration assays, Western blot for occludin\",\n      \"journal\": \"Acta biochimica et biophysica Sinica\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — single lab, single method set, limited mechanistic validation of the LLGL2-occludin link\",\n      \"pmids\": [\"39394821\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"LLGL2 overexpression in endometrial cancer cells activates the Hedgehog signaling pathway (upregulating SHH, PTCH1, SMO, GLI1), and this effect is reversed by the Hedgehog inhibitor JK184, placing LLGL2 upstream of Hedgehog pathway transduction.\",\n      \"method\": \"Overexpression and knockdown experiments, Western blot and RT-qPCR for Hedgehog pathway components, pharmacological inhibition with JK184, xenograft mouse model\",\n      \"journal\": \"Cellular signalling\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — single lab, pathway placement based on expression changes with pharmacological epistasis but no direct molecular interaction established\",\n      \"pmids\": [\"39647764\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"LLGL2 is a scaffolding polarity protein that operates in multiple contexts: it forms a trimeric complex with SLC7A5 and YKT6 to regulate leucine transporter surface levels and promote nutrient uptake; it is transcriptionally repressed by Snail (via E-box binding) while reciprocally reducing Snail nuclear localization; it undergoes MDM2-mediated ubiquitin-proteasomal degradation and, when present, stabilizes THBS3 mRNA through CNOT1 interaction to suppress PI3K-Akt signaling; it interacts with ACTN1 to alter cytoskeletal remodeling and inhibit cell invasion; it suppresses autophagosome formation (via Vps34/ATG14L) to modulate EMT; and in vivo loss of Llgl1/2 activates aPKC and NF-κB to cooperate with p53 loss in driving squamous cell carcinoma.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"LLGL2 is a scaffolding polarity protein that links cell-surface nutrient transport, cytoskeletal organization, and epithelial polarity to the control of proliferation and invasion in epithelial tissues [#0, #2]. As a polarity determinant, murine Llgl2 is required for trophoblast cell polarization and polarized invasion during placental branching morphogenesis [#2]. In ER+ breast cancer it assembles into a trimeric complex with the leucine transporter SLC7A5 and the membrane-fusion regulator YKT6 to raise SLC7A5 cell-surface levels and leucine uptake, sustaining proliferation under nutrient stress, and its expression is driven by oestrogen receptor signaling [#0, #1]. LLGL2 expression is itself controlled at the promoter level by Sp-1-dependent basal transcription and by Snail, which binds E-boxes to repress LLGL2; reciprocally, restored LLGL2 reduces Snail nuclear localization and reverses EMT [#3, #4]. LLGL2 protein is targeted for proteasomal degradation by the E3 ligase MDM2, and when present it engages the CCR4-NOT subunit CNOT1 to stabilize THBS3 mRNA and modulate PI3K-Akt signaling [#6]. Through interaction with ACTN1 it redirects alpha-actinin localization to impair actin filament bundling and cytoskeletal-remodeling-dependent invasion [#5], and it restrains autophagosome formation via Vps34/ATG14L, an axis that in turn shapes EMT and proliferation [#7, #8].\",\n  \"teleology\": [\n    {\n      \"year\": 2011,\n      \"claim\": \"Establishing whether mammalian Llgl2 has a non-redundant role in vivo, the knockout defined it as a polarity factor required for directed cell behavior during development.\",\n      \"evidence\": \"Llgl2-knockout mice with histological and cell-biological analysis of placental trophoblasts\",\n      \"pmids\": [\"21606200\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Molecular partners mediating polarized trophoblast invasion not defined\", \"Did not address LLGL2 role outside placenta\"]\n    },\n    {\n      \"year\": 2007,\n      \"claim\": \"Addressing how LLGL2 transcription is set, promoter dissection identified Sp-1 as a driver of basal expression and EGF signaling as a repressive input.\",\n      \"evidence\": \"Luciferase reporter truncations, mithramycin A (Sp-1 inhibition), and EGF treatment of primary hepatocytes\",\n      \"pmids\": [\"18155665\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"EGF-to-promoter signaling intermediates unmapped\", \"No protein-level consequence demonstrated\"]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"To connect LLGL2 to EMT control, work showed a bidirectional antagonism with Snail at the transcriptional level.\",\n      \"evidence\": \"Promoter reporter assays, E-box deletion mutants, ChIP, nuclear localization analysis, and gain-of-function rescue\",\n      \"pmids\": [\"22580609\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Mechanism by which LLGL2 reduces Snail nuclear localization unresolved\", \"No direct LLGL2-Snail physical interaction shown\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Defining a concrete molecular function, LLGL2 was shown to scaffold a transporter complex coupling nutrient uptake to proliferation, downstream of ER.\",\n      \"evidence\": \"Reciprocal Co-IP identifying an SLC7A5-YKT6-LLGL2 trimer, surface and uptake assays, and ER-modulation expression analysis in ER+ breast cancer cells\",\n      \"pmids\": [\"30996345\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Structural basis of trimer assembly unknown\", \"Whether YKT6/SLC7A5 partnership operates outside breast cancer untested\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Testing a downstream signaling role, LLGL2 was linked to calcium influx and PI3K/AKT activation in hepatocellular carcinoma.\",\n      \"evidence\": \"In vitro functional assays, calcium influx measurements, and in vivo tumor models\",\n      \"pmids\": [\"34178676\"],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"Mechanistic link between LLGL2 and calcium influx not defined\", \"Single lab, limited mechanistic detail\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Probing how LLGL2 promotes proliferation, gain/loss-of-function placed it as a suppressor of autophagosome formation in prostate cells.\",\n      \"evidence\": \"siRNA knockdown, overexpression, and Western blot for autophagy markers with proliferation assays\",\n      \"pmids\": [\"36009528\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct molecular target on the autophagy machinery not identified\", \"Single context\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Identifying a cytoskeletal effector, IP-MS revealed ACTN1 as a partner whose localization LLGL2 redirects to suppress invasion.\",\n      \"evidence\": \"IP-MS, localization analysis, in vitro invasion/migration assays, and an in vivo metastasis model in ovarian cancer cells\",\n      \"pmids\": [\"38136424\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Binding interface and stoichiometry undefined\", \"How LLGL2 alters ACTN1 localization mechanistically unknown\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Assessing tumor-suppressive polarity function in vivo, combined Llgl1/2 loss was shown to activate aPKC and NF-\\u03baB and cooperate with p53 loss in driving squamous cell carcinoma.\",\n      \"evidence\": \"Conditional double-knockout mice with Trp53 epistasis and signaling analysis (preprint)\",\n      \"pmids\": [\"36945368\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Cannot resolve LLGL2-specific contribution from LLGL1\", \"Preprint, not peer-reviewed\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Extending the autophagy link, LLGL2 knockdown was shown to induce Vps34/ATG14L-dependent autophagy flux that suppresses EMT.\",\n      \"evidence\": \"siRNA knockdown, rapamycin/3-MA pharmacological epistasis, and shLLGL2 xenografts in prostate cancer cells\",\n      \"pmids\": [\"38720397\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Whether LLGL2 acts directly on Vps34/ATG14L untested\", \"Connection to the breast-cancer transporter function unexplored\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Two studies placed LLGL2 upstream of additional invasion/signaling outputs (occludin regulation; Hedgehog pathway activation).\",\n      \"evidence\": \"siRNA knockdown with invasion assays (OSCC) and overexpression/knockdown with JK184 pharmacological epistasis and xenografts (endometrial cancer)\",\n      \"pmids\": [\"39394821\", \"39647764\"],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"No direct molecular interactions established for either axis\", \"Pathway placements rest on expression changes alone\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Defining upstream and downstream regulation of LLGL2 levels, MDM2 was identified as its E3 ligase and CNOT1-mediated THBS3 mRNA stabilization as a downstream effector tied to PI3K-Akt.\",\n      \"evidence\": \"RIP-seq, shotgun MS (CNOT1), RNA-seq, and proteasome inhibition in colorectal cancer\",\n      \"pmids\": [\"40619612\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"MDM2 ubiquitination site on LLGL2 not mapped\", \"Whether LLGL2 directly binds THBS3 mRNA versus via CNOT1 unresolved\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How LLGL2's distinct activities — transporter scaffolding, ACTN1-cytoskeletal control, autophagy suppression, and mRNA stabilization — are coordinated within a single polarity-dependent program remains unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No unifying biochemical mechanism integrating the multiple reported partners\", \"Context-dependence of tumor-suppressive versus tumor-promoting roles unexplained\", \"No structural model of LLGL2 in any complex\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0060090\", \"supporting_discovery_ids\": [0, 5]},\n      {\"term_id\": \"GO:0008092\", \"supporting_discovery_ids\": [5]},\n      {\"term_id\": \"GO:0003723\", \"supporting_discovery_ids\": [6]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005886\", \"supporting_discovery_ids\": [0]},\n      {\"term_id\": \"GO:0005856\", \"supporting_discovery_ids\": [5]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-9612973\", \"supporting_discovery_ids\": [7, 8]},\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [6]},\n      {\"term_id\": \"R-HSA-382551\", \"supporting_discovery_ids\": [0]}\n    ],\n    \"complexes\": [\n      \"SLC7A5-YKT6-LLGL2 trimeric complex\"\n    ],\n    \"partners\": [\n      \"SLC7A5\",\n      \"YKT6\",\n      \"ACTN1\",\n      \"CNOT1\",\n      \"MDM2\"\n    ],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":6,"faith_total":6,"faith_pct":100.0}}