Effect of inhibition of Akt phosphorylation on apoptosis of non-small cell lung cancer H1299 cells with wild type EGFR and KRAS induced by tumor necrosis factor related apoptosis inducing ligand

Abstract

Objective To explore the effect of inhibiting Akt phosphorylation on tumor necrosis factor related apoptosis inducing ligand (TRAIL)-induced apoptosis of human non-small cell lung cancer (NSCLC) H1299 cells with wild type EGFR and KRAS. Methods The TRAIL-induced apoptosis was examined by the Annexin V-FITC/PI. The expressions of TRAIL-activated Akt phosphorylation and p-Akt were measured by Western blot. After cells were treated with LY294002, an inhibitor of PI3K-Akt pathway, Annexin V-FITC/PI and Western blot were used to analyze the alteration of TRAIL-induced apoptosis and Akt phosphorylation, respectively. Results H1299 cells were not sensitive to TRAIL-induced apoptosis. When TRAIL concentration was 100 ng/ml, the apoptosis rate of the test group was significantly higher than that of the control group [(15.06±1.29) % vs (3.56±0.50) %, t=66.953, P=0.000]. When TRAIL concentration was 500 ng/ml, the difference was not statistically significant compared with apoptosis rate of 100 ng/ml TRAIL group [(18.65±2.09) % vs (15.06±1.29) %, t=2.423, P=0.136]. The expression level of Akt phosphorylation in H1299 cells was increased by TRAIL in a time-dependent way. When cells were pretreated with LY294002, TRAIL-induced Akt phosphorylation was suppressed to baseline level. At the same time, the apoptosis rate in LY294002-treated group was significantly higher than that in TRAIL group [(41.65±4.62) % vs (15.82±0.61) %, t=39.028, P=0.001]. Conclusions TRAIL-induced Akt phosphorylation can antagonize TRAIL-induced apoptosis. Inhibition of Akt phosphorylation can significantly enhance the sensitivity of NSCLC H1299 cells with wild type EGFR and KRAS to TRAIL-induced apoptosis. Key words: Carcinoma, non-small-cell lung; Akt; Tumor necrosis factor related apoptosis inducing ligand; Apoptosis