目的:探讨下调RACK1基因表达对口腔鳞癌细胞生长及放射敏感性的影响。方法:构建RACK1基因的shRNA载体，通过脂质体转染技术将其转入口腔鳞癌HSC-3细胞，G418筛选得到稳定转染细胞。荧光定量RT-PCR和Western blot分别检测细胞中RACK1mRNA和RACK1蛋白表达水平；CCK8实验检测细胞生长能力；流式细胞仪检测细胞凋亡；细胞体外侵袭实验检测细胞侵袭能力；克隆形成实验检测下调RACK1表达联合X射线照射对细胞增殖能力的影响。构建裸鼠移植瘤模型，观察下调RACK1基因表达联合X射线照射对口腔鳞癌的生长抑制作用。结果:RT-PCR和Western blot结果显示转染后HSC-3细胞RACK1mRNA相对表达量明显降低(n P<0.05)，RACK1蛋白表达水平明显降低(n P<0.05)。CCK8实验结果显示下调RACK1表达可抑制HSC-3细胞生长(n P<0.05)，联合X射线照射使细胞凋亡率明显升高(n P<0.05)，外侵袭穿透细胞数显著减少(n P<0.05)。克隆形成实验结果显示shRACK1组的存活分数低于对照组，放射增敏比为1.37(Dn 0值比)。裸鼠移植瘤实验显示shRACK1组照射后瘤体生长缓慢，瘤体体积减小幅度低于对照组(n P<0.05)，瘤体质量低于对照组(n P<0.05)。n 结论:下调RACK1表达可以增强口腔鳞癌细胞的放射敏感性，为提高口腔鳞癌放射敏感性研究提供新思路。“,”Objective:To evaluate the effect of down-regulation of RACK1 expression on growth and radiosensitivity of oral squamous cell carcinoma cells.Methods:The shRNA vector for RACK1 gene was constructed and transfected into HSC-3 cells by lipofectamine. The stably-transfected cell line was obtained by constructing G418. The expression levels of RACK1 mRNA and protein were detected by RT-PCR and Western blot. The cell proliferation was detected by CCK8 assay. Cell apoptosis was examined by flow cytometry. The invasive and metastatic capabilities of cancer cells were assessed by cell invasion assay n in vitro.The effect of X-ray irradiation combined with down-regulation of RACK1 expression upon cell proliferation was assessed by clone formation assay. The xenograft tumor nude mouse model was established to observe the inhibitory effect of down-regulating RACK1 gene expression combined with X-ray irradiation on oral squamous cell carcinoma.n Results:RT-PCR revealed that the expression level of RACK1 mRNA of transfected HSC-3 cells was significantly down-regulated (n P<0.05). Western blot showed that the expression level of RACK1 protein was significantly down-regulated (n P<0.05). CCK8 assay demonstrated that down-regulation of RACK1 expression could remarkably inhibit the growth of HSC-3 cells (n P<0.05). RACK1 gene shRNA interference combined with X-ray irradiation significantly enhanced the apoptosis rate of HSC-3 cells (n P<0.05). The number of invasion cellsn in vitro in the RACK1 silencing group was evidently decreased (n P<0.05). Clone formation assay showed that the survival fraction in the shRACK1 group was significantly lower than that in the control group. The sensitization enhancement ratio was 1.37(ratio of Dn 0 value). Xenograft tumor experiment in nude mice showed that tumor growth was significantly inhibited in the shRACK1 group, the tumor volume was significantly decreased and the tumor mass was significantly lower than those in the control group (all n P<0.05).n Conclusion:Down-regulating RACK1 expression can enhance the radiosensitivity of oral squamous cell carcinoma cells, providing novel thinking to improve the radiosensitivity of oral squamous cell carcinoma.