CD44+/CD24+宫颈癌细胞和耐辐射宫颈癌细胞特性研究

目的 探讨放疗抵抗的宫颈癌细胞特性,揭示宫颈癌复发和转移的机制。方法 用多次分割照射获得耐辐射的宫颈鳞状细胞癌Siha细胞,利用流式细胞仪从宫颈鳞癌的亲代细胞中分选获得CD44+/CD24+宫颈鳞癌细胞。将耐辐射的宫颈鳞癌细胞和CD44+/CD24+宫颈鳞癌细胞设为实验组,亲代宫颈鳞癌细胞设为对照组,分别进行克隆形成实验和肿瘤移植瘤实验,评估实验组细胞是否具备肿瘤干细胞特性。通过Transwell侵袭实验研究实验组及对照组细胞侵袭和转移能力的差异。利用RT-PCR和Western blot检测实验组及对照组细胞OCT-4、Survivin、ABCG2和bcl-2 mRNA的表达,以及与肿瘤转移相关的E-cadherin和vimentin蛋白表达。结果 辐射抵抗的宫颈鳞癌细胞和CD44+/CD24+宫颈鳞癌细胞较亲代宫颈癌细胞高表达抗凋亡蛋白Bcl-2（t=205.26、198.17,P<0.05）和凋亡抑制蛋白survivin（t=896.62、765.34,P<0.05）,并表达肿瘤干细胞相关标志物OCT-4和ABCG2（t=92.13、81.26、220.45、216.32,P<0.05）。两组细胞均具有较强的致瘤能力以及侵袭和转移能力,且表现出E-cadherin下调和vimentin蛋白上调的EMT相关的分子表型变化。结论 放射抵抗的宫颈鳞癌细胞与CD44+/CD24+宫颈鳞癌细胞表现出相同的肿瘤干细胞特性,经历了上皮间质转化过程,放射可以富集宫颈癌干细胞。

The characteristics of CD44+/CD24+ cervical cancer cells and radioresistant cervical cancer cells

Objective To investigate the characteristics of radiation resistance of cervical cancer cells, and to explore the mechanism of tumor recurrence and migration. Methods Cervical cancer cells (Siha) were fractionally irradiated to get radioresistant subpopulation. CD44+/CD24+ Siha cells were sorted with a flow cytometry. Colony-formation tests and tumor xenografts tests were used to evaluate the "stemness" of resistant cells. Stem cell markers were studied using fluorescence-activated cell sorting analyses. Migration and invasiveness were assessed by a Transwell test. Gene and protein expressions were determined by RT-PCR and immunoblotting assay, respectively. Results Radiation-resistant Siha cells and CD44+/CD24+ Siha cells expressed more antiapoptotic protein Bcl-2(t=205.26, 198.17, P<0.05), apoptosis-inhibitory protein Survivin(t=896.62,765.34, P<0.05)and stem cell markers of OCT-4 and ABCG2 (t=92.13, 81.26, 220.45, 216.32, P<0.05). They were more tumorigenic in vitro and in vivo, showed phenotypic and molecular changes of EMT, and had higher abilities of invasion and migration. Conclusions The radioresistant cervical cancer cells and CD44+/CD24+ cervical cancer cells are similar to CSCs and undergo EMT, suggesting that radiation resistance-induced EMT is linked to the generation of CSCs.