A growing amount of evidence supports that microRNA (miRNA) dysregulation is involved in cancer progression by directly downregulating multiple targets. Elucidating the underlying mechanism of miRNA in carcinogenesis may improve diagnostic and therapeutic strategies for malignancy. In the current study, we found that miR-105 expression was markedly downregulated in both hepatocellular carcinoma (HCC) cell lines and clinical HCC tissues, compared with normal human hepatocyte and adjacent non-cancerous tissues, respectively. Ectopic miR-105 expression suppressed, whereas inhibiting miR-105 promoted the proliferation and tumorigenicity of HCC cells both in vitro and in vivo. Furthermore, we demonstrated that miR-105 could deactivated the phosphoinositide 3-kinase (PI3K)/AKT signaling pathway by downregulating insulin receptor substrate-1, 3-phosphoinositide-dependent protein kinase-1 and AKT1 directly, resulting in increasing cyclin-dependent kinase inhibitors 1A and 1B (p21(Cip1) and p27(Kip1)) and decreasing cyclin D1 expression in HCC. Therefore, our results suggest that miR-105 functions as a potential tumor suppressor by inhibiting the PI3K/AKT signaling pathway and might represent a potential therapeutic target for HCC patients.
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