Effects Of Erlotinib Combined With Telmisartan On The Growth And Angiogenesis Of Xenograft Tumor In Nude Mouse Models Bearing Human Non-small Cell Lung Cancer Cells

Purpose:Up to now, there are no reports about erlotinib combined with telmisartan for NSCLC treatment. Therefore, on basis of our previous researches about the effects of telmisartan on the growth and proliferation of human NSCLC cell line A549, this study intends to investigate the effects of erlotinib combined with telmisartan on the growth and angiogenesis of xenograft tumor in nude mouse models bearing human non-small cell lung cancer A549 cells. Methods:Human NSCLC A549 cells were routinely cultured, then cells were harvested and injected subcutaneously into nude mouse BALB/C(nu/nu) to establish the xenograft tumor nude-mouse models. Then 40 nude mice were randomly divided into four groups(Control group, erlotinib group, terlmisartan group and their combination group; 10 mice/group) and the experiments were carried out as the indicated administration schedule(erlotinib 30mg/kg/d, telmisartan 5mg/kg/d, once time/day, lasted for 3weeks). The volume of xenograft tumor during the administration schedule was calculated, the growth curve of xenograft tumor was drawn, and the tumor growth inhibition(TGI, %) was figured out. After the administration schedule, blood was immediately removed by intracardiac puncture, VEGF concentrations of the murine serum were determined by ELISA method. Then tumors were harvested and kept for analysis. Tumor tissue necrosis was detected by HE staining, microvascular density(MVD) and expression of VEGF and Ki-67 proteins were determined by immunohistochemistry(IHC) method. Meanwhile, the expression levels of VEGF protein in xenograft tumor were analyzed by Western blot. Results:Both Erlotinib(30mg/kg/d) and telmisartan(5mg/kg/d) can inhibit the growth of xenograft tumors to some extent, and their combination treatment can further suppress the tumor growth(P<0.05). Compared with erlotinib or telmisartan treatment, their combination can obviously increase tumor necrosis, inhibit neovascularization and decrease the express levels of VEGF protein(P<0.05). Besides, we found that the amount of VEGF concentrations in the murine serum significantly increased in the erlotinib group compared to the control group, whereas there was no significant difference with the telmisartan group. When telmisartan was used in combination, the upraise of VEGF concentration induced by erlotinib was much lower compared to the erlotinib group(P<0.01). In addition, the percentage of proliferative cells stained by Ki-67 in each group exhibited a high degree of expression(from 55% to 65%, P>0.5). Conclusion:Erlotinib combined with telmisartan can synergistically inhibit the growth and angiogenesis of xenograft tumor in nude mouse models bearing human non-small cell lung cancer A549 cells. Its possible mechanism involved the blockage of the VEGF secretion and expression, the decrease of neoangiogenesis and the increase of necrosis on xenograft tumor.