MiR-204-5p Inhibits Gastric Cancer Cell Proliferation By Downregulating USP47 And RAB22A

Objective:To investigate the effects of miR-204-5p on the proliferation of gastric cancer (GC) cells, and to validate its potential molecular mechanism.Methods:(1) We collected 63 paired GC tissues and adjacent noncancerous tissues (NCTs). Total RNA was extracted using TRIzol reagent, and TaqMan miRNA assay was used to detect the levels of miR-204-5p; (2) Cell proliferation assay and colony formation assay were used to investigate the effects of miR-204-5p on the GC cell proliferation; (3)Luciferase reporter assay and western blotting were performed to validate the potential targets of miR-204-5p; (4) Immunohistochemistry (IHC) was used to detect the RAB22A protein levels in 102 paired GC and NCTs.Results:(1) miR-204-5p was frequently downregulated in GC tissues compared with NCTs (P=0.0010); (2) Ectopic miR-204-5p expression repressed GC cell growth; (3) Identification of USP47 and RAB22A as the targets of miR-204-5p, and silencing the expression of USP47 and RAB22A using siRNA phenocopied the proliferation-inhibiting function of miR-204-5p in GC cells; (4) RAB22A protein levels in GC tissues were frequently increased (64.7%) and negatively associated with the miR-204-5p levels (R=-0.263, P=0.047).Conclusion:Our results demonstrate that miR-204-5p acts as a tumor suppressor in GC through inhibiting USP47 and RAB22A, and reveal USP47 and RAB22A to be new oncogenes in GC.