Journal Article Enhancement of radiosensitivity of MCF-7 breast cancer cells subjected to X-ray or carbon-ion irradiations

Yi, Xie  ,  王, 冰  ,  田中, 薫  ,  Hong-Yan, Li  ,  Qiu-Yue, Zhao  ,  Zhang, Hong

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The sensitivity of cancer cells to radiation therapy varies based on cell cycle phase. Here we evaluated the differences between X-ray and carbon-ion irradiation with respect to cellular radiosensitivity and cancer cycle arrest in the breast cancer cell line, MCF-7. The cell survival rate, cell cycle distribution and the presence of apoptosis were measured by clonogenic assay and flow cytometry. BRCA1 and p21 protein levels were analyzed by Western blot, and the levels of human telomerase reverse transcriptase (hTERT) mRNA expression and telomere length were detected with real-time polymerase chain reaction. The results show a significant dose-dependent effects on survival rate, apoptosis and protein levels in the carbon-ion group of MCF-7 cells. Decreased proliferation was not observed at 2 Gy X-ray irradiation. There were significant differences in cellular cycle arrest, apoptosis percentages and BRCA1 and p21 protein expression between X-ray and heavy-ion groups. The results indicated that increasing in BRCA1 and p21 expression, and attenuation of hTERT gene expression induced by heavy-ion irradiation in MCF-7 cells might relate to mechanism of cellular radiosensitivity in G2/M arrested phase.Keywords: Radiosensitivity, Cellular cycle arrest, BRCA1, P21, hTERT, Telomere length

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