microRNA-577 suppresses tumor growth and enhances chemosensitivity in colorectal cancer.

In this work, we aimed to determine the expression and biological functions of microRNA (miR)-577 in colorectal cancer (CRC). The results showed that miR-577 was downregulated in CRC specimens and cell lines. Restoration of miR-577 significantly suppressed the proliferation and colony formation and induced a G0/G1 cell cycle arrest in CRC cells. 5-Fluorouracil (5-FU)-resistant SW480 cells (SW480/5-FU) were found to have elevated levels of miR-577. Ectopic expression of miR-577 enhanced 5-FU sensitivity in SW480/5-FU cells. Heat shock protein 27 (HSP27) was identified as a target gene of miR-577. Enforced expression of HSP27 reversed the effects of miR-577 on CRC cell growth and 5-FU sensitivity. Xenograft tumors derived from miR-577-overexpressing SW480 cells exhibited significantly slower growth than control tumors. In conclusion, our results support that miR-577 acts as a tumor suppressor in CRC likely through targeting HSP27. Therefore, miR-577 may have therapeutic potential in the treatment of CRC.