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

Abstract

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 thestemnessof 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. Key words: Cervical cancer stem cells; Radioresistance; Metastasis; Epithelial-mesenchymal transition