Effects Of Different Sequential Administration Of Erlotinib And Chemotherapy On The NSCLC Cells

Objective:Lung cancer is the leading cause of cancer-related mortality worldwide.Non-small cell lung cancer(NSCLC)accounts for about80%of lung cancers. Platinum-based chemotherapy is the traditional therapy of advanced NSCLC, but its curative effects have reached a plateau. Erlotinib is one of the epidermal growth factor receptor tyrosine kinase inhibitors(EGFR-TKIs) for the treatment of NSCLC.The sequence of some chemotherapies followed by erlotinib improves clinical effect.Patients with EGFR mutations have better responsiveness when treated with erlotinib,but most of lung cancer patients are EGFR wide-type.If the sequence of chemotherapies followed by erlotinib could raise survival rate for patients with EGFR wide-type is not clearly understand.In this study,the different sequential administration of erlotinib and chemotherapy(paclitaxel, cisplatin plus etoposide) is used to detect the best sequential schedule of the antitumor effect in EGFR wide-type NSCLC cell lines and analyze the possible mechanism.This study may provide preclinical evidence for the use of chemotherapies followed by erlotinib in the treatment of lung cancer.Methods:Firstly,A549and NCI-H292cells were exposed to different concentration gradient of erlotinib, paclitaxel and EP regimen(cisplatin plus etoposide) respectively, used MTT assay to measure cytoactive, then calculated50%inhibit concentration(IC5o) by probit method. Secondly, the unit of erlotinib and paclitaxel has6groups:control、erlotinib(E)、paclitaxel(T)、paclitaxel plus erlotinib(T+E)、paclitaxel followed by erlotinib(T-E)、erlotinib followed by paclitaxel(E-T);the unit of erlotinib and EP regimen has6groups:control、erlotinib(E)、cisplatin plus etoposide(EP)、EP plus erlotinib(EP+E)、EP followed by erlotinib(EP-E)、erlotinib followed by EP(E-EP), used MTT assay to measure cytoactive, then calculated cell survival rate of these groups.Lastly, Annexin V-FITC/PI and PI was used to deal with cells respectively, cell cycle and apoptosis was detected by flow cytometry and analysed by software of Modit.Results:1. Erlotinib, paclitaxel and EP regimen inhibited the cell proliferation of A549and NCI-H292in a dose-dependent.2.In A549cell line,both combination and sequential groups have higher inhibition ratio than erlotinib, paclitaxel and EP regimen alone(P<0.05);the cell survival in T-E and EP-E group decreased remarkably than combination and erlotinib ahead groups.In NCI-H292cell line,the combination group has higher inhibition ratio than erlotinib, paclitaxel and EP regimen alone(P<0.05);but the sequential groups don’t show difference in cell survival compared with erlotinib, paclitaxel and EP regimen alone(P>0.05).3.The apoptosis of T-E and EP-E group increased than erlotinib, paclitaxel and EP regimen alone(P<0.05),E-T group had lower apoptosis than T group (P<0.05), E-EP group can decrease apoptosis of EP-induced in A549(P<0.05).4.T-E and EP-E group can induce G2/M phase arrest, E-T and E-EP group can induce G0/G1phase arrest in A549.Conelusion:1. The effect of sequential administration of erlotinib and chemotherapy is related to cell line species and biology background.2.Paclitaxel followed by erlotinib and EP regimen followed by erlotinib are optimal combination sequential schedule.3.The mechanism of maximum antitumor effect of chemotherapy followed by erlotinib may be related to inhibition of damage restore and enhancement of chemotherapy-induced apotosis.