ABSTRACT
Objective To investigate the effects of glutamine (Gln) on proliferation and survival of small cell lung cancer H446 cells, and further to explore the potential mechanism. Methods The proliferation of H446 cells was detected at different time points (0, 24, 48, 72 and 96 h) by CCK-8 assay in Gln (+) group and Gln (-) group, and an optimal time was selected. Under the optimal time, Annexin V-FITC/PI staining, CellTiter-Glo? assay kit and flow cytometer were used to detect cell survival, cellular adenosine triphosphate (ATP) and reactive oxygen species (ROS) levels. Gln (-) group was used as the control group, under the condition of Gln deficiency, cellular ATP, cell proliferation and survival were detected after adding oxaloacetic acid (OAA) or dimethyl-α-ketoglutarate (DM-αKG). Gln (-) group was used as the control group, cellular ROS, cell proliferation, colony and survival were detected after treated with ROS scavenger N- acetyl cysteine (NAC). With different concentrations (0, 2, 5, 10 μmol/L) of glutaminase inhibitor BPTES, the optimal concentration was selected through the colony assay. The cellular ATP and ROS levels and cell proliferation were detected under the optimal concentration. H446 cells were treated with bis-2-(5-phenylacetamido-1,2,4-thiadiazol-2-yl) ethyl sulfide (BPTES), ROS inducer hydrogen peroxide (H2O2) or the combination of them, and cell survival ratio was compared between two groups. Results The proliferation levels of H446 cells at 24, 48, which were decreased most significantly in 72 h in Gln (-) group. When 72 h was used as the optimal time, the cell survival ratio and ATP level were decreased, and the ROS level was increased, in Gln (-) group compared with those of Gln (+) group (P<0.05). There was a higher survival ratio in H446 cells in Gln (-)+OAA group and Gln (-)+DM-αKG group than that of Gln (-) group (P<0.05), but there were no significant differences in cell proliferation and ATP levels between Gln (-) group, Gln (-)+OAA group and Gln (-)+DM-αKG group. The ROS level was reduced, the cell proliferation, colony level and survival ratio were increased in Gln (-)+NAC group compared with those of Gln (-) group (P<0.05). Cloning assay showed that 10μmol/L was the optional concentration. Under this concentration, the proliferation and ATP level were decreased in Gln(+)+BPTES group (P<0.05), and cellular ROS level was up-regulated compared with Gln(+) group. The survival ratio was significantly lower in BPTES+H 2O2 group compared with BPTES (+) group or H2O2 (+) group. Conclusion Glutamine deficiency inhibits the proliferation and survival ratio of H446 cells through enhancing ROS level. BPTES and H2O2 show synergistically inhibitory effect on the survival of H446 cells.