Effects of thrombospondin 1 down-regulation on biological function of lung adenocarcinoma A549 cells

Abstract

Objective To observe the effect of down-regulation of platelet thrombospondin 1 (THBS1) on proliferation, apoptosis and cell cycle of lung adenocarcinoma A549 cells. Methods THBS1 protein expression in lung adenocarcinoma cell lines A549, H1299, H358, H1975, PC9, PG49 and Calu3 was detected by Western blotting. THBS1 small interfering RNA (siRNA) and control siRNA were transfected into A549 cells with the highest expression level of THBS1. The expression of THBS1 protein in THBS1 siRNA group, control group and transfected group was detected by Western blotting. Then cell counting kit-8 (CCK-8) kit was used to detect the proliferation of each group. Cell apoptosis and cell cycle distribution were analyzed by flow cytometry. Results The expression levels of THBS1 protein in different lung adenocarcinoma cell lines were different, of which A549 cells had the highest expression (1.120±0.087; F=358.087, P=0.000). Compared with non-transfected A549 cells and control group: The expression of THBS1 protein in A549 cells transfected with THBS1 siRNA (0.053±0.023) was significantly decreased (P=0.000), the cell proliferation ability was decreased(P=0.000), the apoptosis rates (THBS1 siRNA group: Early apoptosis rate, middle and late apoptosis rate and total apoptosis rate were (17.00±1.33)%, (3.70±0.56)% and (20.71±0.78)% were increased (F values were 115.899, 14.418 and 167.329 respectively, with P values of 0.000, 0.005 and 0.000 respectively), the ratio of G0/G1 phase cells (68.43±2.26)% was significantly increased (F=46.521, P=0.000), ratio of S phase cells (22.33±2.15)% was significantly increased(F=16.621, P=0.004) and G2/M phase cells (9.23±2.35)% decreased (F=9.282, P=0.015), the difference was statistically significant. Conclusion Silencing THBS1 gene and decreasing the expression of THBS1 protein in lung adenocarcinoma A549 cells can weaken cell proliferation ability, promote cell apoptosis and inhibit the cell cycle progression. Key words: Thrombospondin 1; Lung adenocarcinoma; Cell proliferation; Apoptosis; Cell cycle