Effect of radiation-induction on cell cycle and apoptosis in breast cancer cell lines MDA-MB-231 and MCF-7 / 肿瘤研究与临床

ABSTRACT

Objective@#To investigate the properties of radiation-induced changes of cell cycle and apoptosis in breast cancer cell lines MDA-MB-231 and MCF-7, and to further explore its relationship with radiosensitivity.@*Methods@#The two cell lines MCF-7 and MDA-MB-231 were irradiated with 6 MV X-rays. The cell survival curves were fitted by clonogenic formation assay, then according to the radiosensitivity parameters average lethal dose (D0), quasi-threshold dose (Dq) and survival fraction after 2 Gy irradiation (SF2), the radiosensitivity of the two cell lines was compared. The apoptosis rate and cell cycle distribution of the two cell lines were detected by Hoechst 33342 and PI staining.@*Results@#The survival curve of MDA-MB-231 cell line shifted to the right compared with that of MCF-7 cell line. The values of D0, Dq and SF2 of MDA-MB-231 cell line were higher than those of MCF-7 cell line (1.603±0.023 vs. 1.233±0.027, 1.76±0.04 vs. 1.03±0.10, 0.639 3±0.008 2 vs. 0.398 1±0.018 5, t values were -17.981, -11.745, -20.596, P values were 0.000, 0.003, 0.000). The apoptosis rate of MCF-7 cell line was significantly higher than that of MDA-MB-231 cell line at the doses of 2, 4, 8 Gy irradiated 24 h and at the 12, 48 h after 6 Gy X-irradiation (t values were 4.441, 7.299, 10.499, 6.375, 7.743, P values were 0.011, 0.002, 0.000, 0.003, 0.001). Compared with the non-irradiated group, G2 phase arrest appeared in both cell lines after irradiation. The percentage of the G2/M phase in MDA-MB-231 cell line increased as the time or dosage accumulated. Furthmore, the percentage didn't go down even after 48 hours later. However, the blockage began to gradually release in MCF-7 cell line at the dose of 8 Gy irradiated 24 h and the 48 h after 6 Gy X-irradiation. Followed with that, it turned out the percentage of the G0/G1 phase increased [(65.80±0.56)%, (62.53±0.67)%].@*Conclusions@#6 MV X-irradiation with the doses of 2-8 Gy can induce the cell cycle arrest at G1 and G2 phase in MCF-7 cell line, G2 phase in MDA-MB-231 cell line. Thus more apoptosis appears in MCF-7 cell line, which may cause the difference in radiosensitivity between the two cell lines.