可溶性肿瘤坏死因子受体p75检测在X线照射大肠癌细胞株Lovo细胞中的意义

Effect of X ray on shedding of soluble tumor necrosis factor receptor-p75 in human colorectal cancer cells Lovo in vitro

目的:研究X线照射在体外培养人大肠癌细胞株Lovo后,检测培养上清中可溶性肿瘤坏死因子受体p75(sTNFR-p75)水平变化情况。方法:ELISA法检测培养上清中sTNFR-p75水平,流式细胞仪分析细胞凋亡率,光镜及透射电镜观察细胞形态变化。结果:X线照射后大肠癌Lovo细胞上清sTNFR-p75水平显著低于照射前sTNFR-p75水平(P<0.01);光镜观察发现细胞体积缩小,变圆,核缩小,透射电镜观察发现部分细胞核染色质边集,染色质发生固缩。部分细胞核内染色质凝聚,核膜孔消失,核膜呈波纹状皱缩,形成凋亡小体,内含有退变的细胞器。流式细胞仪分析细胞凋亡率显著增高(P<0.05)。结论:X线照射可减少体外培养的大肠癌细胞膜上的sTNFR-p75脱落到上清中,从而提高肿瘤坏死因子(TNF)与癌细胞的结合率,进而增强照射后TNF对肿瘤的诱导凋亡作用。

Objective To investigate the effects of X ray on human colorectal cancer cells for the release of soluble tumor necrosis factor receptor-p75 （sTNFR-p75） from the membranes of tumor necrosis factor receptor-p75. Detecting the level of sTNFR-p75 in the supertanants of human colorectal cancer in vitro. Methods Enzyme-linked immunosorbent assay （ELISA）was used to examine the levels of sTNFR-p75 in the supertanants before and after X ray exposure. Flow cytometry was used to analyze the distribution of adoptotic cells death. Morphological changes were studied through light and transmission electron microscope. Results After X ray exposure, the levels of sTNFR-p75 was significantly lower than that before X ray treatment （P 〈 0.01 ）. X ray treatment of cells resulted in a strong increase of the apoptotic cell death （P 〈 0.05 ）. These morphological changes of Lovo cells which have been treated with Silibinin were observed. Cells shrank and turned round , cytoplasmic condensed and nucleus pycnosised, were observed through the light microscope. Under transmission electron microscope （TEM） nuclear chromatin aggregated to the margin with irregular shape were observed in some early stage cells. In other late stage cells, chromatin condensed to the margin in a crescent shape, the nuclear pores disappeared, and the nuclei became pycnotic and the cell membrane sprouted and formed vacuoles and apoptotie bodies. Conchlsion X-ray exposure could reduce the shedding of sTNFR-p75 from the human colorectal cancer cell membrane to supertanants. This could increase the combination between tumor necrosis factor（TNF） and Lovo cells, and then strengthen the effect of TNF on reducing the Lovo ceils＇ apoptosis.