Long-chain non-coding RNA plasmacytoma variant translocation 1 regulates proliferation, apoptosis and autophagy of lung cancer cells by targeting microRNA-140-5p

Abstract

Objective To determine the effects of long-chain non-coding RNA (LncRNA) plasmacytoma variant translocation 1 (PVT1) on the proliferation, apoptosis and autophagy of lung cancer cells, and to investigate its mechanism. Methods qRT-PCR was used to examine the expression levels of LncRNA PVT1 and microRNA-140-5p (miR-140-5p) in human lung cancer cell line A549 and normal human lung epithelial cell line BEAS-2B. The A549 cells were divided into si-NC group (si-NC transfection) , si-PVT1 group (si-PVT1 transfection) , miR-NC group (miR-NC transfection) , miR-140-5p group (miR-140-5p mimics transfection) , si-PVT1+anti-miR-NC group (si-PVT1+anti-miR-NC co-transfection) , si-PVT1+anti-miR-140-5p group (si-PVT1+anti-miR-140-5p co-transfection) , which were transfected by liposome method. MTT assay was used to examine the proliferation of cells in each group. Flow cytometry was used to measure the apoptosis of cells. Western blotting was used to determine the protein expression levels of LC3 Ⅱ and Ⅰ. Dual luciferase reporter assay was used to determine the fluorescent activity. Results Compared with BEAS-2B cells, the PVT1 expression level significantly increased in A549 cells (1.73±0.14 vs 0.86±0.08, P<0.05) , whereas the miR-140-5p expression level significantly decreased (0.43±0.04 vs 1.06±0.12, P<0.05) . Compared with si-NC group, the expression level of PVT1 in A549 cells in si-PVT1 group decreased (P<0.05) , the cell inhibition rate and apoptosis rate increased (both P<0.05) , the protein expression level of LC3 Ⅱ decreased (P<0.05) , the protein expression level of LC3Ⅰ increased (P<0.05) , and the expression level of LC3Ⅱ/Ⅰ decreased (P<0.05) . Compared with miR-NC group, the expression level of miR-140-5p in A549 cells in miR-140-5p group increased (P<0.05) , the cell inhibition rate and apoptosis rate increased (both P<0.05) , the protein expression level of LC3 Ⅱ decreased (P<0.05) , the protein expression level of LC3 Ⅰ increased (P<0.05) , and the expression level of LC3 Ⅱ/Ⅰ decreased (P<0.05) . PVT1 targeted miR-140-5p. Compared with the si-PVT1+anti-miR-NC group, the cell inhibition rate and apoptosis rate of A549 cells in the si-PVT1+anti-miR-140-5p group decreased (both P<0.05) , the protein expression level of LC3 Ⅱ decreased (P<0.05) , the protein expression level of LC3 Ⅰ increased (P<0.05) , and the expression level of LC3Ⅱ/Ⅰ decreased (P<0.05) . The inhibition of miR-140-5p reversed knockdown of PVT1 on proliferation, apoptosis and autophagy of A549 cells. Conclusion PVT1 may promote the proliferation and autophagy of lung cancer cells and inhibit cell apoptosis. The mechanism may be related to targeting miR-140-5p, which will provide a basis for targeted therapy of lung cancer. Key words: Long-chain non-coding RNA; Plasmacytoma variant translocation 1; MicroRNAs; Lung neoplasms; Autophagy; Proliferation; Apoptosis