X线照射后对乳腺癌细胞凋亡的影响及CDKN1A表达的变化

Effection of Apoptosis on Breast Cancer Cell and Changes of CDKN1A Gene Expression after X-ray Radiation

目的探讨乳腺癌细胞系(MCF-7)X线照射后CDKN1A基因(p21)表达变化及其对细胞凋亡的影响。方法用流式细胞方法检测MCF-7细胞在接受不同剂量X射线照射后CDKN1A基因表达的改变和用RNAi技术抑制CDKN1A基因表达并检测细胞凋亡的变化。结果 MCF-7细胞在接受不同剂量(1、2和4 Gy)X射线照射后CDKN1A蛋白表达有不同程度升高,其中4 Gy照射后升高水平最明显(P<0.05)。在接受4 Gy剂量照射后,CDKN1A蛋白水平在8、12、24、48、72 h均有不同程度增加,其中24 h时较对照组升高3倍(P<0.05)。抑制CDKN1A基因表达后MCF-7细胞凋亡率增加183.9%(P<0.05)。结论乳腺癌细胞在接受4 Gy照射后24 h的CDKN1A表达水平增加最为明显,抑制CDKN1A基因表达可促进细胞凋亡。

Objective To study the changes of expression of CDKN1A gene（p21） after the X-ray radiation on breast cancer cell line（MCF-7） and the effect of expression of CDKN1A on cellular apoptosis.Methods Expression of CDKN1A gene in MCF-7 cells was detected at different time and radiation dose by flow cytometric test.Cellular apoptosis was analyzed under CDKN1A gene inhibition by RNA interfference（RNAi）.Results After the X-ray irradiation on MCF-7 cells with 1,2 and 4 Gy,the expression of CDKN1A protein increased gradually,in which 4 Gy irradiation obtained the maxiamal expression（P0.05）.With 4 Gy radiation,the expression level of CDKN1A protein improved differently after 8,12,24,48,72 h and resulted in triple increase（P0.05） after 24 h of radiation.And the inhibition of CDKN1A expression with RNAi,compared with control group,the apoptosis rate of MCF-7 cells increased 183.9%（P0.05）.Conclusion After 4 Gy radiation,the expression of CDKN1A of breast cancer cells reached the peak at 24 h and the inhibition of its expression might promote the cellular apoptosis.