Circular RNA collagen type V alpha 1 exerts a carcinogenic role in renal cell carcinoma via modulating microRNA-3940-3p/Karyopherin α2 axis.

The circular RNA collagen Vα1 chain (circCOL5A1) is highly expressed in renal cell carcinoma (RCC) and is a candidate marker, but the mechanism is unknown. According to bioinformatics, it is predicted to bind with miR-3940-3p, and karyopherin α2 (KPNA2), a carcinogenic molecule in RCC, could be its target gene. This study aims to clarify the mechanism of circCOL5A1 regulating KPNA2 on renal cell carcinoma (RCC) cells through miR-3940-3 p. circCOL5A1, miR-3940-3p and KPNA2 were detected by RT-qPCR, and epithelial-mesenchymal transition (EMT) markers were detected by Western blot. The characteristics of circCOL5A1 were verified by RNase R and actinomycin D experiments, and its subcellular localization was analyzed by PARIS kit. After transfection and intervention of 786-O cells, proliferation was assessed using Cell Counting Kit-8 (CCK-8) and colony formation experiments, migration and invasion were evaluated with scratch healing and Transwell assays, and apoptosis was measured through flow cytometry. Glucose uptake, lactic acid production, and ATP/ADP were measured by kits to evaluate glycolysis. The targeting relationship of circCOL5A1, miR-3940-3p and KPNA2 was verified by dual luciferase reporter gene assay and RNA immunoprecipitation (RIP) assay. In results: in RCC tissues/cells, circCOL5A1 and KPNA2 were significantly increased, and miR-3940-3p was significantly decreased (P<0.05). The stability of circCOL5A1 was higher than that of linear COL5A1, and it was mainly distributed in the cytoplasm (P<0.05). Silencing circCOL5A1 could inhibit the proliferation, migration and invasion of 786-O cells, promote apoptosis, down-regulate EMT markers (N-cadherin, Vimentin, Snail) and glycolysis (P<0.05), and up-regulate E-cadherin (P<0.05). CircCOL5A1 targeted miR-3940-3p, and miR-3940-3p targeted KPNA2 (P<0.05). miR-3940-3p inhibitor could reverse the effect of silencing circCOL5A1, and si-KPNA2 could reverse the effect of miR-3940-3p inhibitor (P<0.05). We concluded that the circCOL5A1/miR-3940-3p/KPNA2 axis was a key pathway for RCC progression. CircCOL5A1 promoted cell proliferation, migration, invasion, EMT and glycolysis by cytoplasmic adsorption of miR-3940-3p and up-regulation of KPNA2 in RCC. CircCOL5A1 is anticipated to be a promising molecular target for diagnosing and treating RCC.