MicroRNA-200b and microRNA-200c (miR-200b/c) are 2 of the most frequently upregulated oncomiRs in colorectal cancer cells. The role of miR-200b/c during colorectal tumorigenesis, however, remains unclear. In the present study, we report that miR-200b/c can promote colorectal cancer cell proliferation via targeting the reversion-inducing cysteine-rich protein with Kazal motifs (RECK). Firstly, bioinformatics analysis predicted RECK as a conserved target of miR-200b/c. By overexpressing or knocking down miR-200b/c in colorectal cancer cells, we experimentally validated that miR-200b/c are direct regulators of RECK. Secondly, an inverse correlation between the levels of miR-200b/c and RECK protein was found in human colorectal cancer tissues and cell lines. Thirdly, we demonstrated that repression of RECK by miR-200b/c consequently triggered SKP2 (S-phase kinase-associated protein 2) elevation and p27(Kip1) (also known as cyclin-dependent kinase inhibitor 1B) degradation in colorectal cancer cells, which eventually promotes cancer cell proliferation. Finally, promoting tumor cell growth by miR-200b/c-targeting RECK was also observed in the xenograft mouse model. Taken together, our results demonstrate that miR-200b/c play a critical role in promoting colorectal tumorigenesis through inhibiting RECK expression and subsequently triggering SKP2 elevation and p27(Kip1) degradation.
Keywords: 3′-UTR, 3′-untranslated region; CDKN1B, cyclin-dependent kinase inhibitor 1B; CRC, colorectal cancer; EMT, epithelial-mesenchymal transition; EdU, 5-ethynyl-2′-deoxyuridine; MMP, metalloproteinase; NAT, normal adjacent tissue; ORF, open reading frame; RECK; RECK, reversion-inducing cysteinerich protein with Kazal motifs; SKP2, S-phase kinase-associated protein 2; ZEB, zinc finger E-box-binding protein; cell proliferation; colorectal cancer; miR-200b/c; miR-200b/c, microRNA-200b and microRNA-200c; miRNA, microRNA; oncogene; siRNA, small interfering RNA.