miR-149 regulates the proliferation and apoptosis of human colonic carcinoma cells by targeting FZD5.

To explore the effects of miR-149 on the cell proliferation and apoptosis of colorectal cancer (CRC) and its potential molecular mechanism. miR-149 expression patterns were detected in human CRC cell lines by quantitative real-time RT-PCR (Q-PCR). Online prediction software and luciferase reporter assay were performed to screen the functional targets of miR-149. CRC cells were transfected with miR-149 mimics or siRNAs of FZD5 and then divided into NC group (negative control), miR-149 mimics group (cells transfected with miR-149 mimics) and miR-149 mimics + SiFZD5 group (cells transfected by miR-149 mimics and SiFZD5). Moreover, the effects of miR-149 on the proliferation and apoptosis of CRC cells were also analyzed by MTT and flow cytometry assay. In addition, the expression of Wnt/β-catenin signal pathways related factors were shown by western blot analysis. Q-PCR results demonstrated that the expression of miR-149 was significantly lower in SW480 than that in the FHC cell line. Frizzled class receptor 5 (FZD5) was identified as a functional target of miR-149 through a series of experiments including Q-PCR, western blot analysis, and luciferase assay. Cellular functional experiments demonstrated that the cell viability and proliferation were greatly inhibited after miR-149 overexpression in SW480 cells. Furthermore, the proportion of apoptotic cells increased significantly after introducing miR-149 into SW480 cells. Furthermore, Wnt/β-catenin signal pathway was activated because of the lower expression of β-catenin and cyclinD1 in miR-149 mimics group. However, reducing FZD5 expression restored the expression of β-catenin and cyclin D. Our data suggested that miR-149 may function as a tumor suppressor in CRC cells lines by targeting FZD5. miR-149/FZD5 may become a new therapeutic target for CRC.