Analysis of the synergistic effect of triptolide combined with gefitinib on EGFR-mutant NSCLC cells / 中国药房

ABSTRACT

OBJECTIVE To investigate the synergistic effect of triptolide （TPL） combined with epidermal growth factor receptor tyrosine kinase inhibitor （EGFR-TKI） gefitinib on EGFR-mutated non-small cell lung cancer （NSCLC） cells and its potential mechanism. METHODS Human NSCLC cell lines H1975 （EGFR T790M/L858R mutated drug-resistant cell lines） and H1299 （EGFR wild-type non-drug-resistant cell lines） were cultured in vitro. MTT method was used to detect cell activity， and the effect of combined medication was evaluated by the combination index （CI）. The H1975 cells were divided into blank group， low- concentration and high-concentration groups of TPL （5 nmol/L or 15 nmol/L）， gefitinib group （2 μmol/L）， low-concentration and high-concentration groups of TPL+gefitinib （5 nmol/L TPL+2 μmol/L gefitinib， 15 nmol/L TPL+2 μmol/L gefitinib）. Flow cytometry was used to detect the apoptosis of H1975 cells and the distribution of the cell cycle. Molecular docking studies were used to predict the binding ability of TPL to EGFR. The expressions of phosphatidylinositol 3 kinase （PI3K）/protein kinase B （Akt）/mammalian target of rapamycin （mTOR） pathway and autophagy-related proteins [microtubule-associated protein 1 light chain 3α （MAP1LC3A）， MAP1LC3B] in H1975 cells were detected by flow cytometry. RESULTS TPL had a strong inhibitory effect on the proliferation of H1975 and H1299 cells in a time-dependent and dose-dependent manner. Forty-eight hours treatment of 5 or 15 nmol/L TPL combined with gefitinib had a synergistic inhibitory effect on the proliferation of H1975 cells （CI＜1）， while there was no synergistic inhibitory effect on H1299 cells （CI＞1）. Compared with the blank group， the apoptosis rate and the proportion of H1975 cells at G0/G1 phase were increased significantly in administration groups， while the proportions of cells at S phase and G2/M phase （except for several TPL groups） were decreased significantly， and the combination group had better effects （P＜0.05）. Molecular docking studies showed that the hydroxyl radical of TPL could form hydrogen bonds with the Thr854 residue of the product encoded by EGFR T790M/L858R mutation. Compared with the blank group， the expressions of pathway-related proteins were down-regulated significantly in administration groups， while those of autophagy-related proteins were up-regulated significantly， and the combination group had better effects （P＜0.05）. CONCLUSIONS TPL combined with gefitinib can synergically inhibit the proliferation activity of EGFR-mutated NSCLC cells， the mechanism of which may be related to the down-regulation of PI3K/Akt/ mTOR pathway and induction of autophagy.