Resistance of CD44+/CD24+ expressing cervical cancer cells on apoptosis induced by X-ray irradiation / 中华放射医学与防护杂志

ABSTRACT

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.