Zhang Jiangguo, Xu Gaosi
Department of Morphology, Medical College of Huzhou Teachers No. 1, Xueshi Road, Huzhou 313000, China.
Cancer Genet Cytogenet. 2007 Dec;179(2):112-7. doi: 10.1016/j.cancergencyto.2007.08.015.
To elucidate if the Fas/FasL signal pathway participates in the immune escape of tumor cells, and if contemporary Fas/FasL and tumor necrosis factor (TNF))-induced apoptosis is better for immune cell survival than just blocking Fas/FasL-induced apoptotic signal. FasL expression in mouse H22 hepatocellular cancer cells was suppressed by the siRNA technique. The wild-type Ad5 14.7K gene was amplified by polymerase chain reaction and transduced into Jurkat T-cells. Apoptosis of target Jurkat cells was detected by flow cytometry. TNF-alpha in the culture supernatant of H22 cells by ELISA was seen. FasL and 14.7K gene expression in stably transfected or transduced clones were determined by Western blotting. As a result, FasL expression in H22 cells was down-regulated after stable transfection with a plasmid encoding antisense FasL cDNA. Down-regulation of FasL expression in H22 cells had no effect on tumor growth in vitro. There was an apparent decrease in the number of apoptotic Jurkat T-cells after coculture with transfected H22 cells, relative to coculture with FasL-expressing untransfected cells. Compared with untransduced Jurkat cells, apoptotic rates in 14.7K-transduced Jurkat cells were significantly reduced in three different E/T ratios (P < 0.01), respectively. We conclude that Fas/FasL signal pathway participates in the immune escape of tumor cells by inducing immune cells apoptosis. Reducing the expression of FasL in tumor cells can decrease the apoptotic rate of immune cells, further blocking the apoptotic signal pathway of immune cells by preventing TNF-induced apoptosis can increase the survival of immune cells.
为阐明Fas/FasL信号通路是否参与肿瘤细胞的免疫逃逸，以及当代Fas/FasL和肿瘤坏死因子（TNF）诱导的凋亡是否比单纯阻断Fas/FasL诱导的凋亡信号更有利于免疫细胞存活。通过小干扰RNA（siRNA）技术抑制小鼠H22肝癌细胞中的FasL表达。通过聚合酶链反应扩增野生型腺病毒5型14.7K基因并转导至Jurkat T细胞中。通过流式细胞术检测靶Jurkat细胞的凋亡情况。通过酶联免疫吸附测定法检测H22细胞培养上清液中的TNF-α。通过蛋白质免疫印迹法测定稳定转染或转导克隆中的FasL和14.7K基因表达。结果，用编码反义FasL cDNA的质粒稳定转染后，H22细胞中的FasL表达下调。H22细胞中FasL表达的下调对体外肿瘤生长没有影响。与用表达FasL的未转染细胞共培养相比，与转染的H22细胞共培养后，凋亡Jurkat T细胞的数量明显减少。与未转导的Jurkat细胞相比，在三种不同的效应细胞与靶细胞比例（E/T）下，14.7K转导的Jurkat细胞的凋亡率均显著降低（P < 0.01）。我们得出结论，Fas/FasL信号通路通过诱导免疫细胞凋亡参与肿瘤细胞的免疫逃逸。降低肿瘤细胞中FasL的表达可以降低免疫细胞的凋亡率，通过阻止TNF诱导的凋亡进一步阻断免疫细胞的凋亡信号通路可以提高免疫细胞的存活率。
