Effect Of Trastuzumab On Radiosensitivity Of HER2Overexpressed Gastric Cancer Line

Objective:To study the radiosensitivity of trastuzumab on HER2overexpressed gastric cancer cell NCI-N87.Methods:To identify the expression of HER2in gastric cancer cell with immunohistochemical (IHC) method and the fluorescence in situ hybridization (FISH) method; The inhibitory effect of trastuzumab on cell proliferation was measured by CCK8assay, to select the IC20concentration of trastuzumab on NCI-N87cell; Acorrding to if trastuzumab was used or not, groups were divided into the control group and the group given medicine, they were both given five different doses of external irradiation (0、1、2、4、6、8Gy), then we used the colonogenic assay to analyze the radiosensitizing effect,and then the radiosensitivity parameters were calculated; we divided the groups into blank group、group with medicine、 radiation group (2Gy), combination group (trastuzumab+2Gy), cell apoptosis was analyzed by the flow cytometry.Results:HER2protein mainly distributed in cell membrane was2+, the number of HER2/CEP17>2, so NCI-N87cell was the HER2overexpressing cell.The selected concentration of trastuzumab was10ug/ml. The D0、Dq、N and SF2of the group with medicine were all smaller than the control group. The SER was1.2453.Either trastuzumab or radiation induced cell apoptosis,particularly was the combined group (P<0.05)Conclusions:Trastuzumab could increase the radiosensitivity of NCI-N87cell with high expression of HER2, induce apoptosis. Trastuzumab could be a radiation sensitizer for gastric tumors with high expression of HER2.