放射诱导多倍体乳腺癌细胞衰老和自噬

目的探讨衰老和自噬在放射诱导的多倍体乳腺癌细胞中的作用。方法在6 MV X射线模式下用7 Gy剂量照射乳腺癌MDA?MB?231细胞,分别于第3天(Day 3组)、5天(Day 5组)、7天(Day 7组)、11天(Day 11组)和19天(Day 19组)观察细胞形态变化,采用流式细胞术检测细胞倍性,β?半乳糖苷酶检测细胞衰老情况,Western blot检测衰老和自噬相关蛋白的表达。应用GEPIA工具分析PLK1在乳腺组织及乳腺癌组织中的表达差异。结果7 Gy剂量照射后,Day 3组、Day 5组、Day 7组MDA?MB?231细胞体积变大,多倍体细胞亚群(DNA含量>4 N)比例均明显高于未经放射处理的对照组MDA?MB?231细胞(均P<0.0001),同时发生细胞衰老现象。与未经放射处理的对照组相比,Day 3组和Day 5组中DNA损伤修复蛋白PARP,DNA合成相关蛋白Rb、E2F?1、E2F?2表达下调,自噬相关蛋白LC3B/LC3A比值显著升高;核膜完整性相关蛋白Lamin B1、DNA损伤修复蛋白PARP表达下调,DNA损伤应答相关蛋白PLK1表达上调,差异均有统计学意义(均P<0.05)。与乳腺组织相比,PLK1在乳腺癌组织中高表达(P<0.05)。结论放射诱导乳腺癌细胞发生衰老现象可能是多倍体细胞形成的有利条件,衰老和自噬现象也可能有助于多倍体细胞自我修复去倍化增殖。

Radiation-induced senescence and autophagy in polyploid breast cancer cells

Objective To investigate the role of senescence and autophagy in radiation-induced polyploidy breast cancer cells. Method Breast cancer MDA-MB-231 cells were irradiated with a dose of 7 Gy in 6 MV X-ray mode, and the cell morphology changes were observed on the 3rd (Day 3 group), 5th (Day 5 group), 7th (Day 7 group), 11th (Day 11 group) and 19th (Day 19 group) days, respectively. The cell ploidy was detected by flow cytometry, cell senescence was detected by β-galactosidase, and the expression of senescence and autophagy related proteins was detected by Western blot. The GEPIA tool was used to analyze the difference of PLK1 expression between breast tissues and breast cancer tissues. Results After 7 Gy dose irradiation, the volume of MDA-MB-231 cells in Day 3 group, Day 5 group and Day 7 group became larger, and the proportion of polyploid cell subsets (DNA content>4 N) was significantly higher than that of the control group MDA-MB-231 cells without radiation treatment (all P<0.0001), and cell senescence occurred at the same time. Compared with the control group MDA-MB-231 cells without radiation treatment, the expression of DNA damage repair protein PARP and DNA synthesis related proteins Rb, E2F-1, E2F-2 were down-regulated in Day 3 and Day 5 groups. The ratio of phage-related protein LC3B/LC3A was significantly increased. The expression of nuclear membrane integrity-related protein Lamin B1 and DNA damage repair protein PARP were down-regulated, and the expression of DNA damage response-related protein PLK1 was up-regulated, the differences were statistically significant (all P<0.05). Compared with breast tissues，PLK1 was highly expressed in breast cancer tissues (P<0.05). Conclusions Radiation-induced senescence of breast cancer cells can be a favorable condition for the formation of polyploid cell. Senescence and autophagy may contribute to self-repair and deploid proliferation of polyploid cells.