Purpose: There is mounting evidence to indicate that microRNA-17 (miR-17) is expressed and functionally involved in human cancers. However, the molecular mechanism underlying the role of miR-17 in colorectal cancer (CRC) remains largely unclear. This study aims to reveal the biological function of miR-17 in colorectal cancer.
Materials and methods: The expression of miR-17 in CRC cells and tissues was examined using qRT-PCR. Cell proliferation and migration assays were performed after transfection with an miR-17 mimic and inhibitors. The potential gene targets of miR-17 were predicted by bioinformatics analysis and further validated by PCR, Western blot and dual luciferase reporter assays.
Results: The expression of miR-17 was significantly upregulated in CRC cell lines and tissues and may imply poor prognosis. miR-17 upregulation promoted cell invasion and migration in CRC cell lines in vitro, while downregulation of miR-17 inhibited tumor progression. SIK1  was identified as a potential direct target of miR-17 by dual luciferase reporter assay, and its downregulation in CRC may suggest poor prognosis.
Conclusions: Our study indicated that upregulated miR-17 may promote the progression of CRC and may exert its function as a tumor suppressor miRNA by targeting SIK1 .
Keywords: SIK1, colorectal cancer, prognosis, tumor biomarker