CD44+/CD24+宫颈癌细胞对X射线照射诱导凋亡的抗拒性

目的 探讨CD44+/CD24+宫颈癌细胞的放射抗拒性机制。方法 体外培养人宫颈鳞癌(Siha)细胞,6 MV X射线给予8、16、30 Gy照射,流式细胞仪分选出CD44+/CD24+细胞。采用克隆形成实验拟合细胞存活曲线,比较细胞的放射敏感性;Hochest 33258荧光染色和透射电镜观察细胞形态变化;流式细胞术(FCM)分析细胞凋亡率;凝胶电泳观察凋亡细胞的DNA条带;反转录-聚合酶链反应(RT-PCR)法检测细胞凋亡相关基因mRNA的表达。结果 随着剂量的增加,CD44+/CD24+宫颈癌细胞比例逐渐增加;CD44+/CD24+细胞放射敏感性下降(t=93.99~400.45,P<0.05);CD44+/CD24+细胞中bcl-2、survivin、Oct4基因表达水平较亲代Siha细胞升高(t=221.35、941.65、82.27,P<0.01);Hochest 33258、透射电镜、DNA片段凝胶电泳及流式细胞定量研究显示, Siha细胞出现明显细胞凋亡改变,而Siha CD44+/CD24+细胞则未出现。结论 CD44+/CD24+宫颈癌细胞抵抗放疗的机制是抗拒射线诱导的细胞凋亡。

Resistance of CD44+/CD24+ expressing cervical cancer cells on apoptosis induced by X-ray irradiation

Objective To explore whether CD44+/CD24+ expressing cervical cancer cells are resistant to X-ray irradiation and investigate the underlying mechanism. Methods Cervical cancer cell line (Siha) was cultured in vitro and the CD44+/CD24+ expressing cells were sorted with a flow cytometer. The cells were irradiated with 8, 16 and 30 Gy of 6 MV X-rays. Colony formation test was used to evaluate the radiosensitivity of CD44+/CD24+ expressing cervical cancer cells. Cell morphology was observed by electronmicroscopy, cell apoptosis was analyzed with a flow cytometer and also verified with a DNA "ladder" assay. Gene expression was determined by RT-PCR. Results After radiation, the ratio of CD44+/CD24+ cells significantly increased. Compared to Siha cells, the radiosensitivity of CD44+/CD24+ cells decreased (t=93.99-400.45, P<0.05), and the expressions of bcl-2, survivin and Oct4 mRNA increased in CD44+/CD24+ cells (t=221.35, 941.65, 82.27, P<0.01). Both apoptotic body and specific DNA "ladder" pattern were observed in cells but not in the CD44+/CD24+ Sihacells which had no obvious morphological changes of apoptosis. Conclusions The CD44+/CD24+ expressing cervical cancer cells are resistant to X-rays due to expression of anti-apoptosis factors.