Downregulation of microRNA‐6125 promotes colorectal cancer growth through YTHDF2‐dependent recognition of N6‐methyladenosine‐modified GSK3β

BACKGROUND: MicroRNAs (miRNAs), the key regulator of gene expression, and N6‐methyladenosine (m6A) RNA modification play a significant role in tumour progression. However, regulation of m6A‐modified mRNAs by miRNAs in colorectal cancer (CRC), and its effect on progression of CRC, remains to be investigated. METHODS: Expression of miR‐6125 and YTH Domain‐Containing Family Protein 2 (YTHDF2) was detected by western blotting and immunohistochemistry. The effects of miR‐6125 and YTHDF2 on proliferative capacity of CRC cells were analysed using soft agar, ATP, CCK8 and EdU assays, and in animal experiments. RESULTS: MiR‐6125 expression was downregulated markedly in CRC, and expression correlated negatively with tumour size and prognosis. MiR‐6125 targeted the 3′‐UTR of YTHDF2 and downregulated the YTHDF2 protein, thereby increasing the stability of m6A‐modified glycogen synthase kinase 3 beta (GSK3β) mRNA. Increased GSK3β protein levels inhibited the expression of Wnt/β‐catenin/Cyclin D1 pathway‐related proteins, leading to G0‐G1 phase arrest and ultimately inhibiting the proliferation of CRC cells. CONCLUSIONS: MiR‐6125 regulates YTHDF2 and thus plays a critical role in regulating the Wnt/β‐catenin pathway, thereby affecting the growth of CRC. Collectively, these results suggest that miR‐6125 and YTHDF2 are potential targets for treatment of CRC.