Effects Of Combination Icotinib Hydrochloride With1α,25-dihydroxyxitamin D₃on The Proliferation And Expressions Of EGFR On A549Cells

Background and ObjectiveThe mortality of lung cancer is highest in malignant cancers around the world.Non-small cell lung cancer (NSCLC) accounts for about80%of lung cancer andabout70%of patients with non-small cell lung cancer are diagnosed in the late, wholost the chance of operation and have to choose chemotherapy, radiotherapy, surgery,supportive care and combination of these means. While the efficacy of traditionalchemotherapy seems to have entered a plateau, with objective response rateapproximately30%, a median survival8-9months, one-year survival rate30%-40%.In recent years, the epidermal growth factor receptor tyrosine kinase inhibitors(EGFR-TKIs) appear to bring tremendous benefits for patients suffered from lungcancer. However, EGFR-TKIs is more suitable for patients whose tumors harboractivating EGFR mutations, but mutations within the EGFR gene occur inapproximately10%of all lung adenocarcinoma. So in order to improve the overallefficiency of the treatment in patients with lung adenocarcinoma, we should pay moreattention to the other patients whose tumors do not harbor activating EGFR mutations.Studies have shown that EGFR-TKIs may be effective in patients with EGFRoverexpression.1α,25-dihydroxyvitamin D3has played an important role not only in the regulation of calcium and phosphorus and the maintenance of the steady state ofbone but also for the development and prognosis of tumors. It has been proved that1α,25-dihydroxyvitamin D3could inhibit the growth of human lung adenocarcinomaA549cells. On the other hand, there are a number of studies have shown that1α,25-dihydroxyvitamin D3can regulate the expression of EGFR gene in a variety oftumor cells, such as breast cancer, UMR106-01osteoblast-like cells, ovarian cancer,prostate cancer and so on，but few studies in lung cancer. Therefore, this study wantto investigate whether1α,25-dihydroxyvitamin D3and icotinib hydrochloric conductsynergistic anti-proliferative effect on A549cells. If the answer is yes, we continue toexplore the possible mechanism of this effect. This will be provide experimental basisfor further research on1α,25-dihydroxyvitamin D3combing with icotinibhydrochloride to apply to patients suffering from lung cancer.MethodsThe human lung adenocarcinoma A549cells were cultured in vitro and treatedby icotinib hydrochloride，1α,25-dihydroxyvitaminD3and combination of this twomedicines at different concentration and time interval. After a certain time，theCCK-8assay was applied to analyze the proliferation inhibition rate. The expressionsof EGFR total protein and EGFR mRNA were detected by western blotting andRT-PCR, respectively.ResultsCompared with the single drug groups, there was synergistic effect when treatedwith icotinib hydrochloride and1α,25-dihydroxyxitaminD3along(F=248.45，1564.25and6590.17，P＜0.01）. Compared with the control group and the group treated withicotinib hydrochloride alone, the expressions of EGFR total protein and EGFRmRNA of the group treated with1α,25-dihydroxyxitaminD3alone or the combinationgroup were elevated dramatically（P＜0.05）. Conclusion1. There is synergistic effect when the cells are treated with combinationicotinib hydrochloride with1α,25-dihydroxyxitaminD3.2.1α,25-dihydroxyxitaminD3can up-regulates the expressions of EGFRmRNA and EGFR total protein dramatically.