Effect of microRNA-202-3p on cell proliferation and targeting of ADP-ribosylation factor-like 5A in human colorectal carcinoma.

Abstract

e14667 Background: MicroRNAs (miRNAs) are small, non-coding RNAs that are strongly implicated in cancer and reshaped our understanding of the role of non-protein-coding genes in carcinogenesis. Methods: Quantitative RT-PCR was used to evaluate miR-202-3p expression in 94 pairs of human primary CRC and adjacent noncancerous tissues (NCT) to determine the clinicopathologic significance of miR-202-3p. Cell proliferation analysis and Xenograft analysis was used to investigate miR-202-3p function in vitro and in vivo.It’s direct target ARL5A was confirmed by Luciferase assay and Western blot. Immunochemistry was performed to reveal endogenous protein level of ARL5A and analysis clinical significance. Results: In this study, miR-202-3p was verified significantly down regulated in 46.7% (44/94) of the CRC tissues when compared to the corresponding noncancerous tissues(NCT). Subsequently, DNA copy number deletion of Pre-miR-202 in 63.2%(24/38) CRC tissue was proved(compared with NCT), which was considered as a main cause of the low expression of miR-202-3p. Cell proliferation analysis and colony formation assay showed that overexpression of miR-202-3p inhibit CRC cell growth in vitro. Xenograft analysis revealed that ectopic expression of miR-202-3p decreased the tumorigenicity of CRC cells in vivo. Consistent with these results, silencing of miR-202-3p resulted in a increased growth ratio of the colon cancer cells. In addition, ADP-ribosylation factor-like 5A(ARL5A) was predicted as potential target of miR-202-3p which was confirmed by Luciferase assay and Western blot. Overexpression of miR-202-3p could reduced the endogenous protein level of ARL5A, whereas silencing of miR-202-3p obviously up regulated ARL5A expression. In human CRC tissues, miR-202-3p expression levels correlated inversely with ARL5A protein levels which was identified as an prognostic factor in this study. Furthermore, knockdown of ARL5A phenocopied the proliferation-inhibiting effect of miR-202-3p. Conclusions: These results indicated that miR-202-3p, acting as a new tumor suppressor in CRC, could decrease cell proliferation via directly targeting ARL5A, a first reported gene related to CRC prognosis.