miR‐3133 inhibits gastrointestinal cancer progression through activation of Hippo and p53 signalling pathways via multi‐targets

BACKGROUND: Malignant cell growth and chemoresistance, the main obstacles in treating gastrointestinal cancer (GIC), rely on the Hippo and p53 signalling pathways. However, the upstream regulatory mechanisms of these pathways remain complex and poorly understood. METHODS: Immunohistochemistry (IHC), western blot and RT‐qPCR were used to analyse the expression of RNF146, miR‐3133 and key components of Hippo and p53 pathway. CCK‐8, colony formation, drug sensitivity assays and murine xenograft models were used to investigate the effect of RNF146 and miR‐3133 in GIC. Further exploration of the upstream regulatory mechanism was performed using bioinformatics analysis, dual‐luciferase reporter gene, immunoprecipitation assays and bisulfite sequencing PCR (BSP). RESULTS: Clinical samples, in vitro and in vivo experiments demonstrated that RNF146 exerts oncogenic effects in GIC by regulating the Hippo pathway. Bioinformatics analysis identified a novel miRNA, miR‐3133, as an upstream regulatory factor of RNF146. fluorescence in situ hybridization and RT‐qPCR assays revealed that miR‐3133 was less expressed in gastrointestinal tumour tissues and was associated with adverse pathological features. Functional assays and animal models showed that miR‐3133 promoted the proliferation and chemotherapy sensitivity of GIC cells. miR‐3133 affected YAP1 protein expression by targeting RNF146, AGK and CUL4A, thus activating the Hippo pathway. miR‐3133 inhibited p53 protein degradation and extended p53's half‐life by targeting USP15, SPIN1. BSP experiments confirmed that miR‐3133 promoter methylation is an important reason for its low expression. CONCLUSION: miR‐3133 inhibits GIC progression by activating the Hippo and p53 signalling pathways via multi‐targets, including RNF146, thereby providing prognostic factors and valuable potential therapeutic targets for GIC.