{"gene":"B3GNT3","run_date":"2026-06-09T22:02:44","timeline":{"discoveries":[{"year":2023,"finding":"B3GNT3 catalyzes N-glycosylation of 4F2hc (SLC3A2), thereby stabilizing the 4F2hc protein and enhancing the interaction between 4F2hc and xCT (system Xc-); knockout of B3GNT3 or deletion of its enzymatically active form sensitizes PDAC cells to ferroptosis by impairing system Xc- activity and reducing intracellular glutathione.","method":"N- and O-linked glycoproteomics, B3GNT3 knockout, catalytic mutant rescue, reconstitution of 4F2hc-deficient cells with WT vs. glycosylation-mutated 4F2hc, co-immunoprecipitation, in vitro and orthotopic in vivo models","journal":"Cell death and differentiation","confidence":"High","confidence_rationale":"Tier 1-2 / Strong — multiple orthogonal methods including glycoproteomics, KO, catalytic mutant, glycosylation-site mutant rescue, and Co-IP, all in a single rigorous study with in vivo validation","pmids":["37479744"],"is_preprint":false},{"year":2013,"finding":"B3GNT3 overexpression suppresses T antigen (core 1 O-glycan) formation in neuroblastoma cells and reduces malignant phenotypes (migration, invasion) by decreasing phosphorylation of FAK, Src, paxillin, Akt, and ERK1/2; conversely, B3GNT3 knockdown enhances these phenotypes.","method":"B3GNT3 overexpression and knockdown in SK-N-SH cells, migration/invasion assays, western blotting for signaling phosphoproteins, immunohistochemistry on tumor tissues","journal":"Cancer science","confidence":"Medium","confidence_rationale":"Tier 2-3 / Moderate — clean KD/OE with defined cellular phenotype and downstream signaling readout, single lab, two complementary functional approaches","pmids":["24118321"],"is_preprint":false},{"year":2018,"finding":"GALNT3 and B3GNT3 are overexpressed in pancreatic cancer stem cells (PCSCs) and knockdown of either glycosyltransferase decreases cell-surface expression of CD44v6 and ESA as well as self-renewal markers SOX2 and OCT3/4; CRISPR/Cas9-mediated GALNT3 KO also decreased self-renewal, clonogenicity, and migration of PCSCs.","method":"RT-qPCR, immunoblotting, immunofluorescence, transient knockdown and CRISPR/Cas9 KO, tumorsphere formation, clonogenicity, migration assays, side-population analysis","journal":"BMC cancer","confidence":"Medium","confidence_rationale":"Tier 2-3 / Moderate — CRISPR KO and transient knockdown with multiple functional readouts; B3GNT3-specific mechanistic link is indirect (co-expressed with GALNT3, no B3GNT3-specific CRISPR KO reported)","pmids":["30466404"],"is_preprint":false},{"year":2021,"finding":"B3GNT3 promotes endometrial cancer cell growth, invasion, and migration through upregulation of GTP-bound (active) RhoA and RAC1; B3GNT3 downregulation reduces active RhoA and RAC1, while overexpression has the opposite effect.","method":"Loss- and gain-of-function B3GNT3 assays in HEC-1-A and KLE cells, CCK-8, clone formation, Transwell assays, western blotting for GTP-RhoA and GTP-RAC1","journal":"Genes & genomics","confidence":"Low","confidence_rationale":"Tier 3 / Weak — single lab, single method type (western blot for active RhoA/RAC1), no direct biochemical link between B3GNT3 glycosyltransferase activity and RhoA/RAC1 activation established","pmids":["33683574"],"is_preprint":false},{"year":2023,"finding":"ETV4 binds to the B3GNT3 promoter and activates B3GNT3 transcription; B3GNT3 in turn activates the TGF-β signaling pathway downstream of ETV4, promoting liver cancer cell proliferation, migration, invasion, and EMT.","method":"Chromatin immunoprecipitation (ChIP), dual-luciferase reporter assay, qRT-PCR, B3GNT3 knockdown, TGF-β pathway inhibitor (SB525334) treatment, in vitro functional assays","journal":"Genes & genomics","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — ChIP and dual-luciferase reporter directly demonstrate ETV4 binding to B3GNT3 promoter; epistasis (B3GNT3 KD rescues ETV4 OE phenotype) places B3GNT3 downstream of ETV4 and upstream of TGF-β; single lab","pmids":["37523127"],"is_preprint":false},{"year":2025,"finding":"FUT3 physically interacts with B3GNT3 (co-immunoprecipitation) and this interaction activates NF-κB signaling, driving autophagy and chemoresistance in pancreatic ductal adenocarcinoma.","method":"Co-immunoprecipitation, RNA sequencing, RT-qPCR, western blotting, immunofluorescence, electron microscopy, FUT3 knockdown xenograft model","journal":"European journal of medical research","confidence":"Medium","confidence_rationale":"Tier 2-3 / Moderate — Co-IP demonstrates FUT3-B3GNT3 physical interaction; NF-κB activation and autophagy phenotype supported by multiple assays; single lab, no direct demonstration of B3GNT3 enzymatic contribution to complex","pmids":["41366466"],"is_preprint":false},{"year":2026,"finding":"B3GNT3 physically interacts with NFKB2, facilitating p100 phosphorylation and processing into p52 and its nuclear accumulation, thereby activating non-canonical NF-κB signaling to promote lung adenocarcinoma proliferation, invasion, anoikis resistance, and tumor growth; a catalytically inactive B3GNT3 mutant retains full ability to interact with NFKB2 and promote p100 processing and EMT, demonstrating the oncogenic function is independent of glycosyltransferase activity.","method":"Co-immunoprecipitation coupled with mass spectrometry, Co-IP, catalytic inactive mutant generation, NFKB2 genetic ablation rescue, transcriptomic profiling, gain/loss-of-function experiments, xenograft tumor model","journal":"Cellular oncology (Dordrecht, Netherlands)","confidence":"High","confidence_rationale":"Tier 1-2 / Strong — IP-MS identifies NFKB2 as interactor, confirmed by Co-IP; catalytic mutant rigorously separates enzymatic from non-enzymatic function; genetic ablation of NFKB2 rescues phenotype (epistasis); multiple orthogonal methods in single study","pmids":["41838238"],"is_preprint":false},{"year":2026,"finding":"TCN1 positively regulates B3GNT3 expression via activation of the EGFR pathway; B3GNT3 knockdown suppresses proliferation, metastasis, EMT, and glycolysis in NSCLC cells, and overexpression of B3GNT3 partially rescues the effects of TCN1 knockdown.","method":"qRT-PCR, western blotting, CCK-8, Transwell, EMT and glycolysis assays, KEGG pathway analysis, rescue experiments, in vivo xenograft model","journal":"Pathology, research and practice","confidence":"Low","confidence_rationale":"Tier 3 / Weak — pathway placement (TCN1→EGFR→B3GNT3) inferred from rescue experiments without direct biochemical demonstration of EGFR-mediated B3GNT3 regulation; single lab, limited mechanistic depth","pmids":["41579832"],"is_preprint":false}],"current_model":"B3GNT3 is a β-1,3-N-acetylglucosaminyltransferase that, beyond its canonical role in forming extended core 1 O-glycans and N-glycosylating substrates such as 4F2hc (stabilizing it and enhancing its interaction with xCT to regulate ferroptosis resistance), also functions in a catalysis-independent manner by physically interacting with NFKB2 to facilitate p100 processing and non-canonical NF-κB activation, and can be activated transcriptionally by ETV4 to drive TGF-β signaling; collectively these mechanisms promote cancer cell survival, invasion, stemness maintenance, and immune evasion."},"narrative":{"mechanistic_narrative":"B3GNT3 is a β-1,3-N-acetylglucosaminyltransferase that functions in cancer cells through both glycosyltransferase-dependent and catalysis-independent mechanisms to promote survival, invasion, and stemness [PMID:37479744, PMID:41838238]. In its enzymatic role, B3GNT3 N-glycosylates 4F2hc (SLC3A2), stabilizing the protein and enhancing its interaction with xCT to sustain system Xc- activity and intracellular glutathione, such that its loss sensitizes pancreatic cancer cells to ferroptosis [PMID:37479744]. Independent of catalysis, B3GNT3 physically interacts with NFKB2 to drive p100 phosphorylation, processing to p52, and nuclear accumulation, thereby activating non-canonical NF-κB signaling to promote proliferation, invasion, anoikis resistance, and EMT — a function fully retained by a catalytically inactive mutant [PMID:41838238]. B3GNT3 expression is transcriptionally driven by ETV4, which binds its promoter and engages downstream TGF-β signaling to support proliferation, migration, and EMT in liver cancer [PMID:37523127]. Through control of cell-surface O-glycosylation, B3GNT3 also modulates malignant phenotypes and downstream FAK/Src/Akt/ERK signaling [PMID:24118321].","teleology":[{"year":2013,"claim":"Established the first functional link between B3GNT3 and malignant behavior by showing its O-glycan modifying activity restrains tumor cell migration and invasion through adhesion/survival signaling.","evidence":"B3GNT3 overexpression and knockdown in neuroblastoma cells with migration/invasion assays and phosphoprotein western blotting","pmids":["24118321"],"confidence":"Medium","gaps":["No direct glycan substrate mapping for the signaling changes","Direction of effect (tumor-suppressive) contrasts with later oncogenic findings in other cancers","Single cell-line context"]},{"year":2018,"claim":"Implicated B3GNT3 in cancer stem cell maintenance, linking its glycosyltransferase function to surface markers and self-renewal programs.","evidence":"Knockdown and CRISPR KO of glycosyltransferases in pancreatic cancer stem cells with tumorsphere, clonogenicity, and marker assays","pmids":["30466404"],"confidence":"Medium","gaps":["B3GNT3-specific CRISPR KO not performed (co-studied with GALNT3)","Direct glycosylation of CD44v6/ESA not demonstrated","Mechanistic link to SOX2/OCT3/4 indirect"]},{"year":2021,"claim":"Connected B3GNT3 to small GTPase activation, proposing a route to invasion via RhoA/RAC1.","evidence":"Loss- and gain-of-function in endometrial cancer cells with GTP-RhoA/RAC1 western blots and migration assays","pmids":["33683574"],"confidence":"Low","gaps":["No biochemical link between glycosyltransferase activity and GTPase activation","Single method type (active-GTPase western blot)","Single lab"]},{"year":2023,"claim":"Defined a discrete enzymatic mechanism by which B3GNT3 controls ferroptosis resistance through N-glycosylation and stabilization of the system Xc- subunit 4F2hc.","evidence":"Glycoproteomics, B3GNT3 KO, catalytic and glycosylation-site mutant rescue, Co-IP, and orthotopic in vivo models in PDAC","pmids":["37479744"],"confidence":"High","gaps":["Whether other glycoprotein substrates contribute to ferroptosis control","In vivo relevance to therapy beyond models studied"]},{"year":2023,"claim":"Placed B3GNT3 within a transcriptional circuit, showing it is a direct ETV4 target that relays into TGF-β signaling to drive EMT.","evidence":"ChIP, dual-luciferase reporter, knockdown epistasis, and TGF-β inhibitor treatment in liver cancer cells","pmids":["37523127"],"confidence":"Medium","gaps":["Mechanism by which B3GNT3 activates TGF-β signaling not defined","Enzymatic vs non-enzymatic contribution not separated","Single lab"]},{"year":2025,"claim":"Identified a physical partner (FUT3) whose interaction with B3GNT3 activates NF-κB to promote autophagy-driven chemoresistance.","evidence":"Co-IP, RNA-seq, and FUT3 knockdown xenograft in PDAC","pmids":["41366466"],"confidence":"Medium","gaps":["Enzymatic contribution of B3GNT3 to the complex not tested","Reciprocal validation and structural basis of interaction absent","Single lab"]},{"year":2026,"claim":"Revealed a catalysis-independent oncogenic mechanism: B3GNT3 binds NFKB2 to drive non-canonical NF-κB activation, decoupling its tumor-promoting function from glycosyltransferase activity.","evidence":"IP-MS, Co-IP, catalytic-inactive mutant, NFKB2 genetic ablation rescue, and xenograft in lung adenocarcinoma","pmids":["41838238"],"confidence":"High","gaps":["Structural basis of B3GNT3-NFKB2 interaction unknown","How a glycosyltransferase accesses cytoplasmic/nuclear NF-κB machinery unresolved","Relationship to canonical NF-κB/FUT3 axis not integrated"]},{"year":2026,"claim":"Positioned B3GNT3 downstream of a TCN1/EGFR axis regulating proliferation, metastasis, and glycolysis in NSCLC.","evidence":"qRT-PCR, western blot, functional assays, KEGG analysis, rescue experiments, and xenograft","pmids":["41579832"],"confidence":"Low","gaps":["Direct biochemical demonstration of EGFR-mediated B3GNT3 regulation absent","Pathway placement inferred from rescue only","Single lab"]},{"year":null,"claim":"It remains unresolved how B3GNT3's dual enzymatic (glycan-modifying) and non-enzymatic (protein-interaction) functions are coordinated within a single cell and across tumor types.","evidence":"","pmids":[],"confidence":"Low","gaps":["No structural model of B3GNT3 protein-protein interactions","Subcellular routing reconciling Golgi glycosyltransferase activity with NF-κB engagement undefined","Context dependence of tumor-suppressive vs oncogenic roles unexplained"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0016740","term_label":"transferase activity","supporting_discovery_ids":[0,1]},{"term_id":"GO:0140096","term_label":"catalytic activity, acting on a protein","supporting_discovery_ids":[0]}],"localization":[],"pathway":[{"term_id":"R-HSA-392499","term_label":"Metabolism of proteins","supporting_discovery_ids":[0]},{"term_id":"R-HSA-162582","term_label":"Signal Transduction","supporting_discovery_ids":[4,6]}],"complexes":[],"partners":["SLC3A2","NFKB2","FUT3"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q9Y2A9","full_name":"N-acetyllactosaminide beta-1,3-N-acetylglucosaminyltransferase 3","aliases":["Beta-1,3-galactosyl-O-glycosyl-glycoprotein beta-1,3-N-acetylglucosaminyltransferase","Beta-1,3-galactosyltransferase 8","Beta-1,3-GalTase 8","Beta3Gal-T8","Beta3GalT8","b3Gal-T8","Beta-3-Gx-T8","Core 1 extending beta-1,3-N-acetylglucosaminyltransferase","Core1-beta3GlcNAcT","Transmembrane protein 3","UDP-Gal:beta-GlcNAc beta-1,3-galactosyltransferase 8","UDP-GlcNAc:betaGal beta-1,3-N-acetylglucosaminyltransferase 3","BGnT-3","Beta-1,3-Gn-T3","Beta-1,3-N-acetylglucosaminyltransferase 3","Beta3Gn-T3","UDP-galactose:beta-N-acetylglucosamine beta-1,3-galactosyltransferase 8"],"length_aa":372,"mass_kda":42.5,"function":"Beta-1,3-N-acetylglucosaminyltransferase involved in the synthesis of poly-N-acetyllactosamine. Has activity for type 2 oligosaccharides (PubMed:11042166). Also acts as a core1-1,3-N-acetylglucosaminyltransferase (Core1-beta3GlcNAcT) to form the 6-sulfo sialyl Lewis x on extended core1 O-glycans (PubMed:11439191)","subcellular_location":"Golgi apparatus membrane","url":"https://www.uniprot.org/uniprotkb/Q9Y2A9/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/B3GNT3","classification":"Not Classified","n_dependent_lines":26,"n_total_lines":1208,"dependency_fraction":0.02152317880794702},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/B3GNT3","total_profiled":1310},"omim":[{"mim_id":"615357","title":"BETA-1,3-GALACTOSYLTRANSFERASE 8; B3GNT8","url":"https://www.omim.org/entry/615357"},{"mim_id":"615315","title":"BETA-1,3-N-ACETYLGLUCOSAMINYLTRANSFERASE 6; B3GNT6","url":"https://www.omim.org/entry/615315"},{"mim_id":"605864","title":"BETA-1,3-N-ACETYLGLUCOSAMINYLTRANSFERASE 4; B3GNT4","url":"https://www.omim.org/entry/605864"},{"mim_id":"605863","title":"BETA-1,3-N-ACETYLGLUCOSAMINYLTRANSFERASE 3; B3GNT3","url":"https://www.omim.org/entry/605863"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"","locations":[],"tissue_specificity":"Tissue enhanced","tissue_distribution":"Detected in many","driving_tissues":[{"tissue":"intestine","ntpm":41.3},{"tissue":"salivary gland","ntpm":26.3},{"tissue":"stomach 1","ntpm":40.7}],"url":"https://www.proteinatlas.org/search/B3GNT3"},"hgnc":{"alias_symbol":["B3GN-T3","beta3Gn-T3","HP10328","B3GNT-3"],"prev_symbol":["TMEM3"]},"alphafold":{"accession":"Q9Y2A9","domains":[{"cath_id":"3.90.550","chopping":"74-319","consensus_level":"medium","plddt":97.0078,"start":74,"end":319}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q9Y2A9","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q9Y2A9-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q9Y2A9-F1-predicted_aligned_error_v6.png","plddt_mean":88.25},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=B3GNT3","jax_strain_url":"https://www.jax.org/strain/search?query=B3GNT3"},"sequence":{"accession":"Q9Y2A9","fasta_url":"https://rest.uniprot.org/uniprotkb/Q9Y2A9.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q9Y2A9/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q9Y2A9"}},"corpus_meta":[{"pmid":"30466404","id":"PMC_30466404","title":"Novel role of O-glycosyltransferases GALNT3 and B3GNT3 in the self-renewal of pancreatic cancer stem cells.","date":"2018","source":"BMC cancer","url":"https://pubmed.ncbi.nlm.nih.gov/30466404","citation_count":50,"is_preprint":false},{"pmid":"37479744","id":"PMC_37479744","title":"Targeting N-glycosylation of 4F2hc mediated by glycosyltransferase B3GNT3 sensitizes ferroptosis of pancreatic ductal adenocarcinoma.","date":"2023","source":"Cell death and differentiation","url":"https://pubmed.ncbi.nlm.nih.gov/37479744","citation_count":45,"is_preprint":false},{"pmid":"24118321","id":"PMC_24118321","title":"B3GNT3 expression suppresses cell migration and invasion and predicts favorable outcomes in neuroblastoma.","date":"2013","source":"Cancer science","url":"https://pubmed.ncbi.nlm.nih.gov/24118321","citation_count":42,"is_preprint":false},{"pmid":"26709519","id":"PMC_26709519","title":"B3GNT3 Expression Is a Novel Marker Correlated with Pelvic Lymph Node Metastasis and Poor Clinical Outcome in Early-Stage Cervical Cancer.","date":"2015","source":"PloS one","url":"https://pubmed.ncbi.nlm.nih.gov/26709519","citation_count":38,"is_preprint":false},{"pmid":"29483137","id":"PMC_29483137","title":"B3GNT3 overexpression is associated with unfavourable survival in non-small cell lung cancer.","date":"2018","source":"Journal of clinical pathology","url":"https://pubmed.ncbi.nlm.nih.gov/29483137","citation_count":22,"is_preprint":false},{"pmid":"33316775","id":"PMC_33316775","title":"B3GNT3 overexpression promotes tumor progression and inhibits infiltration of CD8+ T cells in pancreatic cancer.","date":"2020","source":"Aging","url":"https://pubmed.ncbi.nlm.nih.gov/33316775","citation_count":17,"is_preprint":false},{"pmid":"33683574","id":"PMC_33683574","title":"B3GNT3 acts as a carcinogenic factor in endometrial cancer via facilitating cell growth, invasion and migration through regulating RhoA/RAC1 pathway-associated markers.","date":"2021","source":"Genes & genomics","url":"https://pubmed.ncbi.nlm.nih.gov/33683574","citation_count":12,"is_preprint":false},{"pmid":"37523127","id":"PMC_37523127","title":"ETV4 facilitates proliferation, migration, and invasion of liver cancer by mediating TGF-β signal transduction through activation of B3GNT3.","date":"2023","source":"Genes & genomics","url":"https://pubmed.ncbi.nlm.nih.gov/37523127","citation_count":9,"is_preprint":false},{"pmid":"36995820","id":"PMC_36995820","title":"The role of B3GNT3 as an oncogene in the growth, invasion and migration of esophageal cancer cells.","date":"2023","source":"Acta cirurgica brasileira","url":"https://pubmed.ncbi.nlm.nih.gov/36995820","citation_count":8,"is_preprint":false},{"pmid":"37065594","id":"PMC_37065594","title":"Experimental study on the suppressive effect of B3GNT3 on the apoptosis of lung adenocarcinoma cells and its application in early screening for lung adenocarcinoma.","date":"2023","source":"Journal of thoracic disease","url":"https://pubmed.ncbi.nlm.nih.gov/37065594","citation_count":5,"is_preprint":false},{"pmid":"41366466","id":"PMC_41366466","title":"FUT3-B3GNT3 interaction promotes pancreatic cancer progression and chemoresistance via NF-κB signaling mediated autophagy.","date":"2025","source":"European journal of medical research","url":"https://pubmed.ncbi.nlm.nih.gov/41366466","citation_count":0,"is_preprint":false},{"pmid":"41579832","id":"PMC_41579832","title":"TCN1 knockdown inhibits the progression and glycolysis of non-small cell lung cancer via regulating B3GNT3.","date":"2026","source":"Pathology, research and practice","url":"https://pubmed.ncbi.nlm.nih.gov/41579832","citation_count":0,"is_preprint":false},{"pmid":"41838238","id":"PMC_41838238","title":"B3GNT3 facilitates NFKB2 processing and non-canonical NF-κB activation to drive lung adenocarcinoma progression.","date":"2026","source":"Cellular oncology (Dordrecht, Netherlands)","url":"https://pubmed.ncbi.nlm.nih.gov/41838238","citation_count":0,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":10443,"output_tokens":2501,"usd":0.034422,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":9574,"output_tokens":2800,"usd":0.058935,"stage2_stop_reason":"end_turn"},"total_usd":0.093357,"stage1_batch_id":"msgbatch_0179Z2pxRYBsXi2xADneafRw","stage2_batch_id":"msgbatch_01LaY9ZaVdgjWArcZo9eqQE5","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2023,\n      \"finding\": \"B3GNT3 catalyzes N-glycosylation of 4F2hc (SLC3A2), thereby stabilizing the 4F2hc protein and enhancing the interaction between 4F2hc and xCT (system Xc-); knockout of B3GNT3 or deletion of its enzymatically active form sensitizes PDAC cells to ferroptosis by impairing system Xc- activity and reducing intracellular glutathione.\",\n      \"method\": \"N- and O-linked glycoproteomics, B3GNT3 knockout, catalytic mutant rescue, reconstitution of 4F2hc-deficient cells with WT vs. glycosylation-mutated 4F2hc, co-immunoprecipitation, in vitro and orthotopic in vivo models\",\n      \"journal\": \"Cell death and differentiation\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 / Strong — multiple orthogonal methods including glycoproteomics, KO, catalytic mutant, glycosylation-site mutant rescue, and Co-IP, all in a single rigorous study with in vivo validation\",\n      \"pmids\": [\"37479744\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"B3GNT3 overexpression suppresses T antigen (core 1 O-glycan) formation in neuroblastoma cells and reduces malignant phenotypes (migration, invasion) by decreasing phosphorylation of FAK, Src, paxillin, Akt, and ERK1/2; conversely, B3GNT3 knockdown enhances these phenotypes.\",\n      \"method\": \"B3GNT3 overexpression and knockdown in SK-N-SH cells, migration/invasion assays, western blotting for signaling phosphoproteins, immunohistochemistry on tumor tissues\",\n      \"journal\": \"Cancer science\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2-3 / Moderate — clean KD/OE with defined cellular phenotype and downstream signaling readout, single lab, two complementary functional approaches\",\n      \"pmids\": [\"24118321\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"GALNT3 and B3GNT3 are overexpressed in pancreatic cancer stem cells (PCSCs) and knockdown of either glycosyltransferase decreases cell-surface expression of CD44v6 and ESA as well as self-renewal markers SOX2 and OCT3/4; CRISPR/Cas9-mediated GALNT3 KO also decreased self-renewal, clonogenicity, and migration of PCSCs.\",\n      \"method\": \"RT-qPCR, immunoblotting, immunofluorescence, transient knockdown and CRISPR/Cas9 KO, tumorsphere formation, clonogenicity, migration assays, side-population analysis\",\n      \"journal\": \"BMC cancer\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2-3 / Moderate — CRISPR KO and transient knockdown with multiple functional readouts; B3GNT3-specific mechanistic link is indirect (co-expressed with GALNT3, no B3GNT3-specific CRISPR KO reported)\",\n      \"pmids\": [\"30466404\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"B3GNT3 promotes endometrial cancer cell growth, invasion, and migration through upregulation of GTP-bound (active) RhoA and RAC1; B3GNT3 downregulation reduces active RhoA and RAC1, while overexpression has the opposite effect.\",\n      \"method\": \"Loss- and gain-of-function B3GNT3 assays in HEC-1-A and KLE cells, CCK-8, clone formation, Transwell assays, western blotting for GTP-RhoA and GTP-RAC1\",\n      \"journal\": \"Genes & genomics\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — single lab, single method type (western blot for active RhoA/RAC1), no direct biochemical link between B3GNT3 glycosyltransferase activity and RhoA/RAC1 activation established\",\n      \"pmids\": [\"33683574\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"ETV4 binds to the B3GNT3 promoter and activates B3GNT3 transcription; B3GNT3 in turn activates the TGF-β signaling pathway downstream of ETV4, promoting liver cancer cell proliferation, migration, invasion, and EMT.\",\n      \"method\": \"Chromatin immunoprecipitation (ChIP), dual-luciferase reporter assay, qRT-PCR, B3GNT3 knockdown, TGF-β pathway inhibitor (SB525334) treatment, in vitro functional assays\",\n      \"journal\": \"Genes & genomics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — ChIP and dual-luciferase reporter directly demonstrate ETV4 binding to B3GNT3 promoter; epistasis (B3GNT3 KD rescues ETV4 OE phenotype) places B3GNT3 downstream of ETV4 and upstream of TGF-β; single lab\",\n      \"pmids\": [\"37523127\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"FUT3 physically interacts with B3GNT3 (co-immunoprecipitation) and this interaction activates NF-κB signaling, driving autophagy and chemoresistance in pancreatic ductal adenocarcinoma.\",\n      \"method\": \"Co-immunoprecipitation, RNA sequencing, RT-qPCR, western blotting, immunofluorescence, electron microscopy, FUT3 knockdown xenograft model\",\n      \"journal\": \"European journal of medical research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2-3 / Moderate — Co-IP demonstrates FUT3-B3GNT3 physical interaction; NF-κB activation and autophagy phenotype supported by multiple assays; single lab, no direct demonstration of B3GNT3 enzymatic contribution to complex\",\n      \"pmids\": [\"41366466\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2026,\n      \"finding\": \"B3GNT3 physically interacts with NFKB2, facilitating p100 phosphorylation and processing into p52 and its nuclear accumulation, thereby activating non-canonical NF-κB signaling to promote lung adenocarcinoma proliferation, invasion, anoikis resistance, and tumor growth; a catalytically inactive B3GNT3 mutant retains full ability to interact with NFKB2 and promote p100 processing and EMT, demonstrating the oncogenic function is independent of glycosyltransferase activity.\",\n      \"method\": \"Co-immunoprecipitation coupled with mass spectrometry, Co-IP, catalytic inactive mutant generation, NFKB2 genetic ablation rescue, transcriptomic profiling, gain/loss-of-function experiments, xenograft tumor model\",\n      \"journal\": \"Cellular oncology (Dordrecht, Netherlands)\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 / Strong — IP-MS identifies NFKB2 as interactor, confirmed by Co-IP; catalytic mutant rigorously separates enzymatic from non-enzymatic function; genetic ablation of NFKB2 rescues phenotype (epistasis); multiple orthogonal methods in single study\",\n      \"pmids\": [\"41838238\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2026,\n      \"finding\": \"TCN1 positively regulates B3GNT3 expression via activation of the EGFR pathway; B3GNT3 knockdown suppresses proliferation, metastasis, EMT, and glycolysis in NSCLC cells, and overexpression of B3GNT3 partially rescues the effects of TCN1 knockdown.\",\n      \"method\": \"qRT-PCR, western blotting, CCK-8, Transwell, EMT and glycolysis assays, KEGG pathway analysis, rescue experiments, in vivo xenograft model\",\n      \"journal\": \"Pathology, research and practice\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — pathway placement (TCN1→EGFR→B3GNT3) inferred from rescue experiments without direct biochemical demonstration of EGFR-mediated B3GNT3 regulation; single lab, limited mechanistic depth\",\n      \"pmids\": [\"41579832\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"B3GNT3 is a β-1,3-N-acetylglucosaminyltransferase that, beyond its canonical role in forming extended core 1 O-glycans and N-glycosylating substrates such as 4F2hc (stabilizing it and enhancing its interaction with xCT to regulate ferroptosis resistance), also functions in a catalysis-independent manner by physically interacting with NFKB2 to facilitate p100 processing and non-canonical NF-κB activation, and can be activated transcriptionally by ETV4 to drive TGF-β signaling; collectively these mechanisms promote cancer cell survival, invasion, stemness maintenance, and immune evasion.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"B3GNT3 is a β-1,3-N-acetylglucosaminyltransferase that functions in cancer cells through both glycosyltransferase-dependent and catalysis-independent mechanisms to promote survival, invasion, and stemness [#0, #6]. In its enzymatic role, B3GNT3 N-glycosylates 4F2hc (SLC3A2), stabilizing the protein and enhancing its interaction with xCT to sustain system Xc- activity and intracellular glutathione, such that its loss sensitizes pancreatic cancer cells to ferroptosis [#0]. Independent of catalysis, B3GNT3 physically interacts with NFKB2 to drive p100 phosphorylation, processing to p52, and nuclear accumulation, thereby activating non-canonical NF-κB signaling to promote proliferation, invasion, anoikis resistance, and EMT — a function fully retained by a catalytically inactive mutant [#6]. B3GNT3 expression is transcriptionally driven by ETV4, which binds its promoter and engages downstream TGF-β signaling to support proliferation, migration, and EMT in liver cancer [#4]. Through control of cell-surface O-glycosylation, B3GNT3 also modulates malignant phenotypes and downstream FAK/Src/Akt/ERK signaling [#1].\",\n  \"teleology\": [\n    {\n      \"year\": 2013,\n      \"claim\": \"Established the first functional link between B3GNT3 and malignant behavior by showing its O-glycan modifying activity restrains tumor cell migration and invasion through adhesion/survival signaling.\",\n      \"evidence\": \"B3GNT3 overexpression and knockdown in neuroblastoma cells with migration/invasion assays and phosphoprotein western blotting\",\n      \"pmids\": [\"24118321\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No direct glycan substrate mapping for the signaling changes\", \"Direction of effect (tumor-suppressive) contrasts with later oncogenic findings in other cancers\", \"Single cell-line context\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Implicated B3GNT3 in cancer stem cell maintenance, linking its glycosyltransferase function to surface markers and self-renewal programs.\",\n      \"evidence\": \"Knockdown and CRISPR KO of glycosyltransferases in pancreatic cancer stem cells with tumorsphere, clonogenicity, and marker assays\",\n      \"pmids\": [\"30466404\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"B3GNT3-specific CRISPR KO not performed (co-studied with GALNT3)\", \"Direct glycosylation of CD44v6/ESA not demonstrated\", \"Mechanistic link to SOX2/OCT3/4 indirect\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Connected B3GNT3 to small GTPase activation, proposing a route to invasion via RhoA/RAC1.\",\n      \"evidence\": \"Loss- and gain-of-function in endometrial cancer cells with GTP-RhoA/RAC1 western blots and migration assays\",\n      \"pmids\": [\"33683574\"],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"No biochemical link between glycosyltransferase activity and GTPase activation\", \"Single method type (active-GTPase western blot)\", \"Single lab\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Defined a discrete enzymatic mechanism by which B3GNT3 controls ferroptosis resistance through N-glycosylation and stabilization of the system Xc- subunit 4F2hc.\",\n      \"evidence\": \"Glycoproteomics, B3GNT3 KO, catalytic and glycosylation-site mutant rescue, Co-IP, and orthotopic in vivo models in PDAC\",\n      \"pmids\": [\"37479744\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether other glycoprotein substrates contribute to ferroptosis control\", \"In vivo relevance to therapy beyond models studied\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Placed B3GNT3 within a transcriptional circuit, showing it is a direct ETV4 target that relays into TGF-β signaling to drive EMT.\",\n      \"evidence\": \"ChIP, dual-luciferase reporter, knockdown epistasis, and TGF-β inhibitor treatment in liver cancer cells\",\n      \"pmids\": [\"37523127\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Mechanism by which B3GNT3 activates TGF-β signaling not defined\", \"Enzymatic vs non-enzymatic contribution not separated\", \"Single lab\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Identified a physical partner (FUT3) whose interaction with B3GNT3 activates NF-κB to promote autophagy-driven chemoresistance.\",\n      \"evidence\": \"Co-IP, RNA-seq, and FUT3 knockdown xenograft in PDAC\",\n      \"pmids\": [\"41366466\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Enzymatic contribution of B3GNT3 to the complex not tested\", \"Reciprocal validation and structural basis of interaction absent\", \"Single lab\"]\n    },\n    {\n      \"year\": 2026,\n      \"claim\": \"Revealed a catalysis-independent oncogenic mechanism: B3GNT3 binds NFKB2 to drive non-canonical NF-κB activation, decoupling its tumor-promoting function from glycosyltransferase activity.\",\n      \"evidence\": \"IP-MS, Co-IP, catalytic-inactive mutant, NFKB2 genetic ablation rescue, and xenograft in lung adenocarcinoma\",\n      \"pmids\": [\"41838238\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Structural basis of B3GNT3-NFKB2 interaction unknown\", \"How a glycosyltransferase accesses cytoplasmic/nuclear NF-κB machinery unresolved\", \"Relationship to canonical NF-κB/FUT3 axis not integrated\"]\n    },\n    {\n      \"year\": 2026,\n      \"claim\": \"Positioned B3GNT3 downstream of a TCN1/EGFR axis regulating proliferation, metastasis, and glycolysis in NSCLC.\",\n      \"evidence\": \"qRT-PCR, western blot, functional assays, KEGG analysis, rescue experiments, and xenograft\",\n      \"pmids\": [\"41579832\"],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"Direct biochemical demonstration of EGFR-mediated B3GNT3 regulation absent\", \"Pathway placement inferred from rescue only\", \"Single lab\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"It remains unresolved how B3GNT3's dual enzymatic (glycan-modifying) and non-enzymatic (protein-interaction) functions are coordinated within a single cell and across tumor types.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"No structural model of B3GNT3 protein-protein interactions\", \"Subcellular routing reconciling Golgi glycosyltransferase activity with NF-κB engagement undefined\", \"Context dependence of tumor-suppressive vs oncogenic roles unexplained\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0016740\", \"supporting_discovery_ids\": [0, 1]},\n      {\"term_id\": \"GO:0140096\", \"supporting_discovery_ids\": [0]}\n    ],\n    \"localization\": [],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-392499\", \"supporting_discovery_ids\": [0]},\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [4, 6]}\n    ],\n    \"complexes\": [],\n    \"partners\": [\"SLC3A2\", \"NFKB2\", \"FUT3\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":5,"faith_total":5,"faith_pct":100.0}}