METTL1-WDR4 promotes the migration and proliferation of gastric cancer through N7-methylguanosine.

Gastric cancer (GC) is one of the most common malignant tumor worldwide. Metastasis is leading cases of cancer-related death of GC. It has been found that N7-methylguanosine (m7G) modifications play an important role in cancer. However, the role of m7G modifications within mRNA and its "writer" METTL1 and WDR4 in tumors, particularly GC, has not been revealed. RT-qPCR, WB and IHC were used to detect the expression of METTL1 and WDR4 in GC cells and tissues. Function-based experiments were performed using METTL1-WDR4 knockdown and overexpression cell lines in vitro and in vivo, including CCK8, colony formation, transwell and nude mice models. Mechanistically, RNA-seq, MeRIP-seq, MeRIP-qPCR, western blot, dot blot, co-IP, ChIP and IHC stainings were performed. METTL1 and WDR4 were upregulated in GC patients. High expression of METTL1 and WDR4 were associated with poor prognosis. Silencing METTL1-WDR4 inhibited GC cell migration and proliferation in vitro and vivo. Mechanistically, METTL1-WDR4 can enhance the mRNA stability of PIK3C2B and AKT by promoting their m7G levels, which leading the overexpression of p-AKT. Interestingly, we also found that on the one hand, the transcription factor YY1 can promote the mRNA transcription expression of METTL1 and WDR4 at the same time, and on the other hand, METTL1-WDR4 can promote YY1 expression by increasing the level of m7G. This regulation presents positive feedback. Above all, METTL1 and WDR4 ultimately up-regulate the level of m7G and promote the malignant progression of GC. These findings suggest that METTL1-WDR4 might serve as a potential diagnostic and prognostic biomarker and a therapeutic target for GC treatment by regulating m7G level.