Abstract
Background: microRNAs (miRNAs) are small non-coding RNAs and have been shown to play a crucial role in the colorectal cancer (CRC) tumorigenesis and progression. The aim of this study was to investigate the clinical significance and prognostic value of miR-140-5p in CRC. The exact functions and the underlying molecular mechanisms of miR-140-5p in CRC was further determined. Methods: miR-140-5p expression was detected in CRC samples, their adjacent nontumor tissues as well as CRC cell lines by RT-qPCR. Cell proliferation was detected using CCK-8, and cell invasion and migration were evaluated using Transwell assay. The direct regulation of VEGFA by miR-140-5p was identified using luciferase reporter assay. Results: miR-140-5p was significantly dowregulated in CRC tissues and cell lines. Downregulation of miR-140-5p was significantly correlated with advanced CRC stage and poorer overall survival. Both gain-of-function and loss of function studies demonstrated that miR-140-5p acted as a tumor suppressor by inhibiting cell proliferation, migration and invasion. Integrated analysis identified VEGFA as a direct and functional target gene of miR-140-5p. Silencing VEGFA by small interfering RNA (siRNA) resembled the phenotype resulting from ectopic miR-140-5p expression, while overexpression of VEGFA attenuated the effect of miR-140-5p on CRC cells. Conclusions: Our results suggested a tumor suppressive role of miR-140-5p in CRC tumorigenesis and progression by targeting VEGFA. Copyright (C) 2015 S. Karger AG, Basel