Abstract: Objective:To explore the expression charateristics of long non-coding RNA bladder cancer associated transcript-1(BLACAT1) in the cancer tissue and cancer cells in the patients with non-small cell lung cancer(NSCLC) and the regulation mechanism,and to elucidate the effect and clinical significance of BLACAT1 in the occurrence and development of NSCLC. Methods:Gene Expression Omnibus (GEO) database was used to analyze the expression characteristics of BLACAT1 in the NSCLC tissue. Kmplot website was used to analyze the correlations between the expression of BLACAT1 and the survival and prognosis of the NSCLC patients. Real-time quantitative PCR(qRT-PCR) method was applied to detect the expressions of BLACAT1 in cancer tissue and corresponding adjacent normal tissue and NSCLC cell lines of the NSCLC patients.The specific small interfering RNA for BLACAT1(si-BLACAT1 group) or negative control sequence(si-NC group) were transfected into the A549 cells. The mRNA expression level of BLACAT1 in A549 cells in various groups were detected by qRT-PCR method; the percentages of A549 cells in different cell cycles were detected by flow cytometry; the clone formation abilities of A549 cells in various groups were detected by cell clone formation experiment. The proliferation activities of cells in various groups were detected by CCK8 assay. qRT-PCR and Western blotting methods were used to detect the expression level of CyclinD1 and CDKN2B mRNA and protein in the A549 cells in various groups. Results:The results of GSE18842 and GSE19804 in GEO datatase,qRT-PCR and Kmplot analysis showed that the expression level of BLACAT1 in NSCLC tissue was significantly increased compared with adjacent normal lung tissue (P< 0.05); the survival time in the patients with low expression of BLACAT1 in cancer tissue was significantly longer than that in the patients with high expression of BLACAT1 (P=0.011). Compared with si-NC group,the BLACAT1 expression level in the A549 cells in si-BLACAT1 group was significantly decreased(P<0.05).Compared with si-NC group, the percentage of A459 cells in G₁ phase in si-BLACAT1 group was increased (P<0.05), and the percentage of A549 cells in S phase was decreased(P<0.05);the cell clone formation ability and the cell proliferation activity were decreased(P<0.05 or P<0.01). Compared with si-NC group, the expression levels of CyclinD1 mRNA and protein in the A549 cells in si-BLACAT1 group were significantly decreased(P<0.05), and the expression levels of CDKN2B mRNA and protein were significantly increased(P<0.05). Conclusion:LncRNA-BLACAT1 is up-regulated in cancer tissue and cancer cells of the NSCLC patients, and down-regulation of BLACAT1 expression can inhibit the proliferation of A549 cellsvia modulating the CyclinD1/CDKN2B axis, which may serve as a potential therapeutic target for the NSCLC patients.

Key words: long non-coding RNA, cancer, non-small cell lung, cell proliferation, prognosis