MicroRNA-103a inhibits proliferation, migration and invasion in colorectal cancer cells

Colorectal cancer (CRC) is the second leading cause of cancer-related death in the western country. MiR-103a is an important post-transcriptional regulator, which has been validated as a tumor suppressor in many human cancers. However, the detailed role of miR-103a in CRC remains to be elucidated. In our study, real-time RT-PCR was performed to detect the expression levels of miR-103a in CRC cell lines and clinical CRC specimens. To further explore the potential role of miR-103a, we restored its expression in CaCO-2 and SW480 cell lines by transfection with miR-103a mimics. Effects of miR-103a on cell proliferation, migration and invasion were evaluated by 3-(4,5-dimethylthi-azol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), wound scratch and trans-well assays. The results showed that miR-103a was significantly down-regulated in both CRC cell lines (P<0.05) and clinical specimens (P<0.05). Decreased expression of miR-103a significantly correlated with lymph node metastasis (P<0.05) and local invasion (P<0.05). Kaplan-Meier survival analysis showed that the CRC patients with low miR-103a levels had a significantly poorer prognosis than those with the high miR-103a levels (P<0.05). Multivariate analysis revealed that miR-103a expression (P<0.05) and lymph node metastasis (P<0.05) could be independent prognostic indicators for overall survival rates of CRC patients. Furthermore, gain-of-function experiment indicated that reintroduction of miR-103a significantly reduced CRC cells growth, migration and migration (All P<0.05). In conclusion, our observations suggest that miR-103a has potential as a prognostic biomarker and functions as a tumor suppressor in CRC.