Effect Of L-Arginine On Proliferation And Apoptosis Of Human Lung Adenocarcinoma Cells A549 And Role Of PI3K/Akt Signal Pathway

Objective: To study the effect of L-Arginine(L-Arg)on apoptosis and proliferation of human lung adenocarcinoma cells A549, and discuss the relative mechanism. Methods: MTT colorimetric assay was used to detected the cell viability of A549 cells, treated by different concentrations of L-Arg(0, 16, 32, 64, 96, 128 mmol/L) for 24, 36, 48 hours respectively,and he morphology changes of cells were observed by using microscope; The apoptosis ratio and cell cycle distribution was detected by the flow cytometry method induced by L-Arg(0, 16, 32, 64, 96 mmol/L) for 48 hours; Meantime, the expression of Akt, phosphorylation of Akt serine 473(p-Akt S473), pro-apoptotic protein Bad and Cleaved Caspase-3 were detected by western blot. Results: 1)Compared to control group, high dose of L-Arg markedly decreased cell viability(1.00 vs 0.58±0.07, P<0.05) and L-Arg could significantly inhibit proliferation of A549 cells as the dose and time increased; 2)Compared with control group, L-arginine, with a high concentrations, could significantly reduce the number of cells and change the morphology as concentration increased. 3) The apoptosis ratio was significantly increased by the gradually increased dose of L-Arg(0.70 ± 0.15% vs 21.40 ± 4.69%, P<0.01), as the same to cell cycle distribution, L-Arg could remarkablly increased the ratio of G0/G1 cell cycle distribution(40.54±6.14% vs 65.57±8.24, P<0.01), comparing to the control group; while ratio of S phase and G2/M was markedly decreaed. 4) The results of western blot indicted that L-Arg significantly decreased phosphorylation of p-Akt S473(1.00 ± 0.08 vs 0.32 ± 0.06, P<0.01); While conversely to the tendency of p-Akt S473, L-Arg remarkablly up-regulated the expression of pro-apoptotic protein Cleaved Caspase-3 and Bad(1.00 ± 0.07 vs 2.99 ± 0.28, P<0.01; 1.00 ± 0.17 vs 2.98 ± 0.31, P<0.01). Conclusion: High dose of L-Arg could inhibit proliferation and increase apoptosis of human lung adenocarcinoma cells A549 and inactivation of PI3K/Akt signal pathway may mediate these anti-tumor effects.