Objective: The aim of this study was to investigate the effect of long non-coding ribonucleic acid (lncRNA)-bladder cancer associated transcript 1 (BLACAT1) on the drug resistance of non-small cell lung cancer (NSCLC) cells in cisplatin (DDP) chemotherapy by regulating the expression of Cyclin D1.
Materials and methods: The analysis of the lncRNA expression profiles in 483 cases of NSCLC tissues and 347 cases of cancer-adjacent tissues in Gene Expression Omnibus (GEO) database revealed that lncRNA-BLACAT1 was differentially expressed in NSCLC and related to prognosis. In order to further study its mechanism of action on DDP-resistant cells, the expression level of lncRNA-BLACAT1 in normal human lung bronchial epithelial cell line BEAS-2B, NSCLC cell line A549, and DDP-resistant cell line A549 (A549/DDP) was detected by quantitative Polymerase Chain Reaction (qPCR). LncRNA-BLACAT1 small interfering RNA (siRNA) (si-BLACAT1) and lncRNA-BLACAT1 negative control (si-NC) were transfected into A549/DPP cells. Then, qPCR was carried out to detect the changes in the expression of lncRNA-BLACAT1 before and after transfection. Thereafter, cell cycle and cell growth rate were detected by flow cytometry and the cell growth curve. Besides, the changes in cell migration, cell apoptosis, and Cyclin D1 were detected via wound healing assay, flow cytometry, and Western blotting (WB).
Results: In GEO database, lncRNA-BLACAT1 was significantly overexpressed in NSCLC (p<0.05), and the prognosis of NSCLC in BLACAT1 low-expression group was better than that in the BLACAT1 high-expression group (p<0.0001). Compared with that in BEAS-2B cells, BLACAT messenger RNA (mRNA) was notably highly expressed in A549 cells (p<0.05), and compared with that in A549 cells, BLACAT1 mRNA in A549/DPP was significantly highly expressed in A549/DDP cells (p<0.05). Additionally, in comparison with that in the si-NC group, the content of lncRNA-BLACAT1 in si-BLACAT1 group was remarkably decreased (p<0.01). Moreover, flow cytometry detection of cell cycle revealed that compared with those in si-NC group, G0/G1 phase was markedly prolonged and S phase was shortened in si-BLACAT1 group. MTS assay manifested that the absorbance at 450 nm in si-BLACAT1 group was evidently decreased on the 3rd day compared with that in the si-NC group (p<0.05), and the difference between the two groups was the most significant on the 5th day (p<0.001). According to wound healing assay, compared with those in si-NC group, the distance between cells became larger, the cell migration ability was remarkably weakened (p<0.05), and cell apoptosis was prominently reduced in si-BLACAT1 group (p<0.05). WB results showed that compared with si-NC group, si-BLACAT1 group had significantly reduced Cyclin D1 (p<0.05) CONCLUSIONS: LncRNA-BLACAT1 regulates the expression of Cyclin D1, reduces the malignant phenotype of drug-resistant cells, and increases the sensitivity of lung cancer cells to DDP.