HER-3基因表达对HER-2阳性型乳腺癌细胞放射敏感性的影响及作用机制

目的:探讨人表皮生长因子受体-3（human epidermal growth factor receptor-3，HER-3）表达对HER-2阳性型乳腺癌细胞放射敏感性的影响。方法:使用慢病毒颗粒感染HER-2阳性型乳腺癌细胞系（AU-565、SKBR-3）构建HER-3基因敲低细胞系模型，蛋白质印迹法（Western blot）及实时定量PCR(RT-qPCR)技术检测感染的效率。克隆形成实验测定不同组别乳腺癌细胞放射增敏效果。将HER-3敲低组与对照组细胞分别给予X线照射（6 Gy,6 MV,源皮距100 cm），流式细胞术测定不同组别细胞凋亡率以及细胞周期分布的变化。免疫荧光法检测细胞辐射后不同时间段的γH2AX焦点数，评估辐射后DNA损伤情况，蛋白质印迹法检测细胞周期调控相关蛋白CyclinB1的表达。结果:克隆形成实验结果显示，HER-3敲低组乳腺癌细胞放射敏感性增强。流式细胞术结果显示，HER-3敲低后，HER-2阳性型乳腺癌细胞辐射后凋亡率明显增加，细胞周期G2期分布比例提高。免疫荧光结果显示，HER-3敲低后，HER-2阳性型乳腺癌细胞γH2AX焦点数目在辐射后先增加后降低，较对照组峰值更高，降低时趋势更慢，提示HER-3敲低可增强辐射诱导的DNA损伤，减少DNA修复。蛋白质印迹法结果显示，细胞周期相关驱动蛋白CyclinB1表达降低。结论:HER-3基因敲低后一方面增加了HER-2阳性型乳腺癌细胞辐射后DNA的损伤并减缓其修复能力，促进细胞凋亡；另一方面通过下调细胞周期蛋白CyclinB1的表达，增加G2期细胞分布，提升了放射敏感性。

The influence and mechanism of HER-3 gene expression on radiosensitivity of HER-2 positive breast cancer cells

Objective:To investigate the influence of the human epidermal growth factor receptor-3（HER-3) expression on the radiosensitivity of HER-2 positive breast cancer cells.Methods:Lentiviral particles were used to infect HER-2 positive breast cancer cell line（AU-565,SKBR-3) to construct a HER-3 knockdown cell model.Real-time quantitative PCR and Western blot were used to detect the effectiveness of transfected cells.Clony-formation assay was used to detect the radiosensitivity of different groups of breast cancer cells.The cells in the HER-3 knockdown group and the control group were given X-ray irradiation（6 Gy,6 MV,source skin distance 100 cm),and flow cytometry was used to determine the apoptosis rate and cell cycle distribution changes in different groups.Immunofluorescence was used to detect γH2AX foci of cells after different time of radiation to assess DNA damage.Western blot was used to detect the expression of cell cycle regulation related protein CyclinB1.Results:The results of clony-formation assay showed that breast cancer cells in the HER-3 knockdown increased radiosensitivity.The results of flow cytometry showed that after HER-3 knockdown,the apoptotic rate of HER-2 positive breast cancer cells increased significantly after radiation,and the G2 phase distribution of the cell cycle was up-regulated.Immunofluorescence results showed that after HER-3 knockdown,the number of γH2AX foci of HER-2 positive breast cancer cells increased first and then decreased after irradiation,which was higher than the control group and had a slower decreasing trend,suggesting that HER-3 knockdown can enhance radiation-induced DNA damage,reducing DNA repair.Western blot results showed the expression of cell cycle related protein CyclinB1 decreased.Conclusion:HER-3 gene knockdown firstly increases the DNA damage of HER-2 positive breast cancer cells after radiation and slows their repair ability,promotes cell apoptosis,and secondly increases the G2 phase distribution by down-regulating the expression of CyclinB1,what improves radiation sensitivity.