The Effect and Mechanism of Autophagy in Inhibiting the Proliferation of A549 Cells Induced by Rh-endostatin and Erlotinib
|Keywords||Erlotinib Rh-endostatin autophagy adenocarcinoma synergy|
Objective: To investigate the effect of growth inhibition and autophagy of lung adenocarcinoma A549 cells induced by Rh-endostatin (Endostar/YH-16) and Erlotinib in different concentrations and the combined treatment of human lung adenocarcinoma cells line A549, and explore the role of autophagy in the treatment of lung cancer and mechanisms to provide new ideas for the treatment of NSCLC.Methods: Human lung adenocarcinoma A549 cells line was chosen as target cells. MTT assay method was used to determine the proliferation inhibition of A549 cells which was respectively treated with Rh-endostatin and Erlotinib alone and in combination. The half inhibitory concentration (IC50) and combination index (CI) were calculated. The existence of autophagosomes in treated A549 cells was observed using transmission electron microscopy (TEM). And the expression level of microtubule-associated protein light chain 3-Ⅱ(LC3-Ⅱ) was tested and quantitated by western blot analysis in each study group. Furthermore, Flow cytometry was used to analyze cell cycle and apoptotic rate of A549 cells after different treatment.Results: (1) Rh-endostatin and Erlotinib monotherapy and combined treatment could inhibit the proliferation of A549 cells in a concentration dependent manner (P<0.05). Synergistic effect was found in the combined treatment group with CI less than 1. (2) Autophagosomes of A549 cells induced by Rh-endostatin and Erlotinib after monotherapy and combined treatment, the amount of autophagosomes was significantly increased compared with the control group, and the amount of autophagosomes in the combined group was more than the mono-drug treated groups. (3) LC3-Ⅱexpression in A549 cells was increased in groups treated with Rh-endostatin and Erlotinib alone and their combination compared with the control group (P<0.05). LC3-Ⅱexpression increased significantly in the combined group than the mono-drug treated groups (P<0.05). (4) Each group with different treatment could affect cell cycle in A549 cells, Rh-endostatin arrested cell cycle at G0/G1 phase but induced significantly decreased S phase compared with the control group (P<0.05). Erlotinib blocked cells at G0/G1 phase while induced significantly decreased G2/M phase. Treatment with Rh-endostatin in combination with Erlotinib group blocked more cells at G0/G1 phase and induced more decreased S phase than the control group and mono-drug treated groups (P<0.05). (5) All the three study groups induced obvious apoptosis in A549 cells compared with the control group (P<0.05), the apoptotic rate in combined groups was increased significantly than that in the two groups treated with sole medication (P<0.05). However, the difference between Rh-endostatin and Erlotinib treated groups was not significant (P>0.05).Conclusion: The combination of Rh-endostatin and Erlotinib in different concentration can induce the inhibition of A549 cells resulting in apoptosis and cell cycle arrest with synergistic effect. In addition, autophagy maybe involved in this process. The results demonstrate that Rh-endostatin and Erlotinib suppressed proliferation and triggered cell death in A549 cells partly by inducing autophagy in a dose-dependent manner.