miR-557 inhibits hepatocellular carcinoma progression through Wnt/β-catenin signaling pathway by targeting RAB10

Accumulating evidence suggests that aberrant miRNAs participate in carcinogenesis and progression of hepatocellular carcinoma (HCC). Abnormal miR-557 expression is reported to interfere with the progression of several human cancers. However, the potential roles of miR-557 in HCC remain largely unknown. In the current study, we found that miR-557 was down-regulated in HCC tissues and cell lines, and was closely related to recurrence and metastasis of HCC. Notably, overexpression of miR-557 inhibited proliferation, migration, invasion, epithelial-to-mesenchymal transition (EMT) progression, blocked cells in G0/G1 phase of MHCC-97H cells in vitro, and suppressed tumor growth in vivo. However, loss of miR-557 facilitated these parameters in Huh7 cells both in vitro and in vivo. Moreover, RAB10 was identified as a direct downstream target of miR-557 through its 3'-UTR. Furthermore, RAB10 re-expression or knockdown partially abolished the effects of miR-557 on proliferation, migration, invasion, and EMT progression of HCC cells. Mechanistically, overexpression of miR-557 suppressed Wnt/β-catenin signaling by inhibiting GSK-3β phosphorylation, increasing β-catenin phosphorylation, and decreasing β-catenin transport to the nucleus, while knockdown of miR-557 activated Wnt/β-catenin signaling. Moreover, the TOP/FOP-Flash reporter assays showed that miR-557 overexpression or knockdown significantly suppressed or activated Wnt signaling activity, respectively. Additionally, low expression of miR-557 and high expression of RAB10 in HCC tissues was closely associated with tumor size, degree of differentiation, TNM stage and poor prognosis in HCC patients. Taken together, these results demonstrate that miR-557 blocks the progression of HCC via the Wnt/β-catenin pathway by targeting RAB10.