Reverse Resistance To Radiation In KYSE-150R Esophageal Carcinoma Cell After Epidermal Growth Factor Receptor Signal Pathway Inhibition By Nimotuzumab

Background:Esophageal carcinoma (EC) is ranked as the fifth leading cause of cancer death in men and the eighth in women worldwide, and almost half of them are Chinese. Most patients present with locally advanced disease, carrying a poor prognosis. Radiotherapy plays an important role in the treatment of esophageal carcinoma, while radio-resistance is the critical factor influences its curative effect. Epidermal growth factor receptor (EGFR) is closely related to the radioresistance in esophageal carcinoma. Increased EGFR expression, found in almost68.2%of patients with esophageal squamous cell carcinoma and32%of adenocarcinoma, has been associated with a worse prognosis. Combination of radiotherapy and EGFR inhibitors can improve radiosensitivity in numerous kinds of tumors. Nimotuzumab is a humanized monoclonal antibody that has equal efficacy and better security compared to other EGFR-targeted antibodies. Given that little is known of the efficacy and related mechanisms of nimotuzumab used to reverse radioresistance in KYSE-150R esophageal carcinoma cell, we investigated the radiosensitization effect of nimotuzumab in combined with radiation. Our results shows that nimotuzumab enhanced the antitumor efficacy of radiation in KYSE-150R esophageal carcinoma cell, providing a rationale for future clinical investigations of the therapeutic efficacy of nimotuzumab in combination with radiotherapy in patients with esophageal carcinoma.Method and Result1The expressions of EGFR and p-EGFR before and after radiation in KYSE-150esophageal carcinoma cell and in KYSE-150R esophageal carcinoma cellFor the establishment of strategy about inhibition of EGFR pathway as a target for radiosensitization, it is very necessary to study the expressions of EGFR and p-EGFR in KYSE-150and in radiation resistance KYSE-150R esophageal carcinoma cell. We assess the expressions of EGFR and p-EGFR in these two kinds of cells before and after radiotherapy through the West blot detection, and found that both cells have increased expressions of p-EGFR after radiotherapy, but it is more obviously in the radiation resistance KYSE150R cell. However, in both cells, the expression of EGFR has no obvious difference before and after radiotherapy. Thus, the activation of EGFR pathway may be associated with radiation resistance in KYSE150R cells, and we established the necessity and potential value of the EGFR pathway inhibition as a target for radiosensitization.2Nimotuzumab-an EGFR inhibitor, can enhance the radiosensitivity of radiation resistance KYSE-150R esophageal carcinoma cellEGFR inhibitors can improve the radiosensitivity of tumor cells. Nimotuzumab is a humanized monoclonal antibody that has equal efficacy and better security compared to other EGFR-targeted antibodies. So we choose nimotuzumab as a research object. Clony-forming assay, cell proliferation test were done to verify the increased sensitivity to IR in radiation resistance esophageal KYSE150R cell. 3The mechanism of nimotuzumab reversing resistance to radiation in KYSE-150R esophageal carcinoma cellIdentification of radiosensitization mechanism for nimotuzumab is essential for its clinical application. In this study, y-H2AX foci assay was done to monitor DNA double-strand breaks (DSBs) repair after irradiation combined with nimotuzumab in KYSE-150R esophageal carcinoma cell. The results indicate that nimotuzumab may enhance radiosensitivity through delaying repair of DNA double-strand breaks (DSBs) after irradiation.Conclusion1The expression of p-EGFR in the radiation resistance KYSE150R cell increased more obviously than KYSE150cell after irradiation, which may be one of the causes of its radiation resistance. Therefore, the use of EGFR inhibitors to reverse its radiation resistance treatment strategy has important clinical significance.2Our results prove that nimotuzumab can improve the radiosensitivity and reverse its radiation resistance in KYSE-150R esophageal carcinoma cell.3Our results indicate that nimotuzumab may enhance radiosensitivity through delaying repair of DNA double-strand breaks (DSBs) after irradiation. This invitro study provide new strategies for improve the treatment in radioresistent esophageal carcinoma, which has important clinical significance.