Abstract: Objective To discover the impact to MDC1 and 53BP1 after silence H2AX and when ionizing radiation in esophageal high grade squamous cell carcinoma ECA109. Methods Construction of lentiviral vector silencing H2AX , then transfecting lentivirus to esophageal cancer ECA109 and detecting the silence effect after transfection. Immunofluorescence detection the nuclear focus of r-H2AX、MDC1 and 53BP1 in ECA109 with ionizing radiation before and after transfection. As well as detection the expression of three proteins by western blot. Results 1) Successfully constructed the silence of H2AX in ECA109 cells. 2) Ionizing radiation can cause r-H2AX expression increases but not MDC1 and 53BP1. Ionizing radiation-induced nuclear focus of r-H2AX, MDC1 and 53BP1 are similar. 3) The nucleus focus of r-H2AX, MDC1 and 53BP1 are significantly reduced in ECA109 after silence H2AX. Protein expression did not change. Conclusion H2AX is one of early ionizing radiation-reaction protein in ECA109 and is located in the damage response upstream and can adjust the position of MDC1 and 53BP1.

Key words: Esophageal carcinoma, HistoneH2AX-PhosPhorylation, MDC1, 53BP1, Nuclear foci