In vitro characterisation of the SETD8-MCM7 axis in driving gastric cancer progression and epithelial-mesenchymal transition.

[BACKGROUND] SETD8, a histone methyltransferase catalyzing H4K20 monomethylation (H4K20me1), is crucial for epigenetic regulation, yet its role in gastric cancer (GC) progression remains unclear. This study investigated whether SETD8 promotes epithelial-mesenchymal transition (EMT) and GC progression by regulating MCM7.

[METHODS] expression and clinical relevance of SETD8 and MCM7 were analyzed using TCGA and GEO databases, and validated in GC cell lines and normal gastric epithelial cells. SETD8 knockdown and inhibitor UNC0379 were used to assess its functions. Proliferation, apoptosis, invasion, migration, EMT and stemness were evaluated by CCK-8, flow cytometry, Transwell, wound healing, immunofluorescence and sphere formation assays. ChIP-qPCR measured H4K20me1 enrichment and SETD8 binding at the MCM7 promoter. Rescue experiments were performed by overexpressing MCM7 in SETD8-knockdown cells. Supplementary single-cell and immunotherapy cohort analyses were also conducted.

[RESULTS] SETD8 and MCM7 were overexpressed in GC tissues and cell lines, correlating with advanced stage and poor prognosis. SETD8 knockdown suppressed proliferation, migration, invasion and stemness, induced apoptosis, and reversed EMT (downregulating Snail, N-cadherin, Vimentin; upregulating E-cadherin). Mechanistically, SETD8 knockdown reduced global H4K20me1 and MCM7 expression. H4K20me1 was enriched at the MCM7 promoter, while direct SETD8 binding was not detected, suggesting a non-canonical regulatory mode. MCM7 overexpression rescued the malignant phenotypes inhibited by SETD8 knockdown.

[CONCLUSION] SETD8 promotes EMT and GC progression primarily by upregulating MCM7 expression, likely via an H4K20me1-dependent epigenetic mechanism. MCM7 acts as a key downstream effector. The SETD8/MCM7 axis represents a novel driver and potential therapeutic target in GC.