Effect of microRNA-135a-5p on proliferation, migration and chemoresistance of pancreatic cancer cell

Objective To investigate the effect of microRNA (miRNA, miR)-135a-5p on proliferation, migration and chemoresistance of pancreatic cancer. Methods Expression of miR-135a-5p in pancreatic cancer tissues and adjacent normal tissues, Panc1 and AsPc-1 cell lines as well as normal pancreatic duct epithelial cell line HPDE were detected by reverse transcription-polymerase chain reaction (RT-qPCR). The Panc1 and AsPc-1 cells were transfected with miR-135a-5p mimics, the proliferation and migration abilities of cells in each group were detected by cell counting kite-8 (CCK-8) assay and scratch assay. Panc1 and AsPc-1 cells were treated with cisplatin of different concentrations, absorbance values were detected by microplate reader and the chemosensitivity to cisplatin were compared in each group. The downstream target genes of miR-135a-5p were predicted using online software and the dual-luciferase reporter gene system was used for verification. The expression levels of branched chain amino acid aminotransferase1 (BCAT1) in each group were detected by Western blotting. Results The expression of miR-135a-5p in pancreatic cancer tissues was significantly lower than that in adjacent tissues (0.23±0.08 vs. 1.03±0.18), and the expression of miR-135a-5p in Panc1 and AsPc-1 cells was significantly lower than that in normal pancreatic duct epithelial cell line HPDE (0.30±0.13, 0.56±0.09 vs. 0.97±0.12, P<0.05). The proliferation and migration ability of Panc1 and AsPc-1 cells in the miR-135a-5p mimic group were significantly inhibited (P<0.05), and the expression levels of BCAT1 protein in the cells were significantly decreased. The dual-luciferase reporter gene system confirmed that miR-135a-5p could target and regulate the expression of BCAT1 gene. The sensitivity of Panc1 cells to cisplatin chemotherapy was significantly increased in the miR-135a-5p mimic group (P<0.05). The co-transfection of Panc1 cells with miR-135a-5p mimic and BCAT1 overexpression vector partially reversed the decreased cell proliferation, decreased migration ability and increased sensitivity to cisplatin chemotherapy mediated by the upregulation of miR-135a-5p. Conclusion MiR-135a-5p is low expressed in pancreatic cancer, and upregulation of miR-135a-5p can inhibit cell proliferation and migration of pancreatic cancer cells by targeting BCAT1 gene, and increase the sensitivity of cisplatin chemotherapy. Key words: MicroRNA-135a-5p; Branched chain amino acid aminotransferase 1; Pancreatic cancer; Drug resistance