Study On The Correlation Between Estrogen Receptor And Anti-estrogen Therapy And The Efficacy Of EGFR-TKI

BackgroundEstrogen might affect the clinicopathological characteristics and survival prognosis of female patients with lung cancer.Previous study in our team have shown that the PFS of premenopausal female patients with lung cancer receiving EGFR-TKI treatment is shorter than that of postmenopausal patients.The level of estrogen and the expression of ER might affect the efficacy of EGFR-TKI.This research aims to study the expression and the pathway of ER in EGFR-mutant lung cancer cells,and explore methods to improve the efficacy of EGFR-TKI from the perspective of estrogen.PART Ⅰ Expression and location of ER in lung adenocarcinoma cells and its effects on the EGFR pathwayMethodsER in the membrane,cytoplasm and nucleus of lung cancer cells was detected by western blot.EGFR-mutant lung adenocarcinoma cells were treated by ER agonist or antagonist.We then detected the level of MAPK and p-MAPK,and detected cells proliferation activity with CCK method.ResultsER-α was expressed in the cytoplasm and nucleus of most lung adenocarcinoma cells.ER-β was expressed in the nucleus of EGFR-wildtype lung adenocarcinoma cells,in the cytoplasm and nucleus of EGFR-mutant lung adenocarcinoma cells.In EGFR-mutant lung adenocarcinoma cells,ER-α and ER-β were expressed in the cell membrane and cytoplasm.ER-β agonist enhanced the phosphorylation of MAPK downstream of EGFR signaling(P<0.01)and increased the proliferation rate of EGFR-mutant lung adenocarcinoma cells(P<0.01)，while ER-β antagonist induced the opposite effect(P<0.001).But ER-α agonist and antagonist had no significant effect as mentioned above.ConclusionsER-β was expressed in the membrane,cytoplasm and nucleus of EGFR-mutant lung adenocarcinoma cells,and expressed in the nucleus of EGFR wild-type lung adenocarcinoma cell,but not in the cytoplasm.Estrogen might activate EGFR signaling through ER-β,and promote the proliferation of EGFR-mutant lung adenocarcinoma cells.PART Ⅱ In vitro study on the combined antitumor effect of anti-estrogens and EGFR-TKIMethodsEGFR-mutant lung adenocarcinoma cells were treated by anti-estrogens,EGFR-TKI alone or in combination.We then detected the cells proliferation activity with CCK method.ResultsThe IC50 of tamoxifen on a variety of lung cancer cells was lower than 20μM,and the IC50 of fulvestrant was higher than 40μM.The proliferation rate of EGFR-mutant lung adenocarcinoma cells treated with erlotinib combined with tamoxifen was lower that of erlotinib alone(P<0.01).The proliferation rate cells treated with erlotinib combined with fulvestrant was not significantly different from that of erlotinib alone(P>0.05).ConclusionsTamoxifen could enhance the effect of erlotinib in inhibiting the proliferation of EGFR-mutant lung adenocarcinoma cells.But fulvestrant did not enhance the inhibitory effect of erlotinibPART Ⅲ Efficacy analysis of targeted therapy in patients with double primary lung cancer/breast cancer and patients with pregnancy-associated NSCLCMethodsWe collected patients diagnosed with double primary lung cancer/breast cancer in our hospital,screened patients with advanced lung cancer who received EGFR-TKI treatment,and compared the efficacy of EGFR-TKI in patients with or without a history of anti-estrogen therapy.Besides,we collected patients with pregnancy-associated NSCLC diagnosed in our hospital or reported in the literature to explore their clinicopathological characteristics and the efficacy of targeted therapy.ResultsA total of five patients with double primary lung cancer/breast cancer received first-generation EGFR-TKI treatment.Among them,three patients with a history of anti-estrogen therapy had PFS of 24months,>17months and 12months,respectively.The PFS of the other two patients without a history of anti-estrogen therapy was 6months and lmonth,respectively.A total of 77 patients with pregnancy-associated NSCLC were collected,34 of whom received genetic test.The EGFR mutation rate was 32%and the ALK rearrangement rate was 47%.The median OS of patients with EGFR mutation was 22months.ConclusionsAnti-estrogen therapy might improve the efficacy of EGFR-TKI in patients with advanced lung adenocarcinoma,but the study sample size should be expanded for further verification.The incidence rate of driver gene in patients with pregnancy-associated NSCLC is high,and the efficacy of targeted therapy is similar to that of ordinary patients.