Restoration of miR-650 leads to down-regulation of KISS1, a possible route involved in overcoming 5-FU resistance and induction of apoptosis in CRC cells in-vitro.

ABSTRACT

BACKGROUND: Colorectal cancer (CRC) is one of the most common cancers and the fourth leading cause of cancer-related deaths worldwide. We aimed to determine the role of miR-650 in CRC pathogenesis. METHODS: In this study, we examined the expression of miR-650 and KISS1 in 80 CRC patients who either received or did not receive chemo agents. For this aim, we assessed the miR-650 and KISS1 expression levels in 80 CRC tissues, 30 of which had no history of chemotherapy. The effect of miR-650 and 5-FU on KISS1 expression was measured using qPCR and Western blotting. Also, the 5- FU effect on miR-650 expression in the CRC cell lines was measured by qRT-PCR. Next, MTT assay and Flowcytometry assays were conducted to determine the role of miR-650 in cell viability and apoptosis. RESULTS: The results showed that miR-650 was down-regulated in CRC tissues. However, patients who received 5-FU before surgery showed increased expression of miR-650. The results for KISS1 were insignificant while administering 5-FU to patients preoperatively increased its expression. In-vitro studies showed that 5-FU led to the up-regulation of miR-650 in the SW480 CRC cell line. Furthermore, the administration of miR-650 and 5-FU downregulated KISS1, especially when combined. Moreover, miR-650 with 5-FU significantly reduced cell viability in CRC cell lines by inducing apoptosis. CONCLUSIONS: These results indicate that miR-650 has a tumor suppressive function, overcoming 5-FU chemoresistance in CRC, and induces apoptosis probably by alleviating KISS1. These results suggest that miR-650 is a potential contributor to CRC pathogenesis.