METHODS: MDA-MB-231 cells were seeded and allowed to incubate for 48 h. The cells were treated with doxorubicin, cisplatin, 5-fluorouracil, or paclitaxel for 48 h. Subsequently, the cells were stimulated with a 60-min PEMF session thrice a day (with an interval of 4 h between each session) for 24 or 48 h. Cell viability was assessed by trypan blue dye exclusion assay and cell-cycle analysis was analyzed by flow cytometry. Molecular mechanisms involved in late G2 arrest were confirmed by a western blot assay and confocal microscopy.
RESULTS: MDA-MB-231 cells treated with a combination of doxorubicin and PEMF had remarkably lower viability than those treated with doxorubicin alone. PEMF stimulation increased doxorubicin-induced cell-cycle arrest in the late G2 phase by suppressing cyclin-dependent kinase 1 (CDK1) activity through the enhancement of myelin transcription factor 1 (MYT1) expression, cell division cycle 25C (CDC25C) phosphorylation, and stratifin (14-3-3σ) expression. PEMF also increased doxorubicin-induced DNA damage by inhibiting DNA topoisomerase II alpha (TOP2A).
CONCLUSIONS: These findings support the use of PEMF stimulation as an adjuvant to strengthen the antiproliferative effect of doxorubicin on breast cancer cells.
方法:将MDA-MB-231细胞接种并孵育48小时。用阿霉素处理细胞,顺铂,5-氟尿嘧啶,或紫杉醇48小时。随后,每天三次(每次间隔4小时)用60分钟的PEMF疗程刺激细胞,持续24或48小时。通过锥虫蓝染料排除试验评估细胞活力,并通过流式细胞术分析细胞周期分析。通过蛋白质印迹分析和共聚焦显微镜证实了G2晚期停滞的分子机制。
结果:用多柔比星和PEMF的组合处理的MDA-MB-231细胞具有显著低于单独用多柔比星处理的细胞的活力。PEMF刺激通过增强髓鞘转录因子1(MYT1)表达来抑制细胞周期蛋白依赖性激酶1(CDK1)活性,从而在G2后期增加阿霉素诱导的细胞周期停滞,细胞分裂周期25C(CDC25C)磷酸化,和分层(14-3-3σ)表达式。PEMF还通过抑制DNA拓扑异构酶IIα(TOP2A)来增加阿霉素诱导的DNA损伤。
结论:这些发现支持使用PEMF刺激作为佐剂来增强多柔比星对乳腺癌细胞的抗增殖作用。