Morotomi-Yano Keiko, Akiyama Hidenori, Yano Ken-ichi
Department of Bioelectrics, Institute of Pulsed Power Science, Kumamoto University, Japan.
Department of Pulsed Power Infrastructure, Institute of Pulsed Power Science, Kumamoto University, Japan.
Arch Biochem Biophys. 2014 Aug;555-556:47-54. doi: 10.1016/j.abb.2014.05.020. Epub 2014 Jun 2.
Exposure of cultured cells to nanosecond pulsed electric fields (nsPEFs) induces various cellular responses, including the influx of extracellular Ca2+ and cell death. Recently, nsPEFs have been regarded as a novel means of cancer therapy, but their molecular mechanism of action remains to be fully elucidated. Here, we demonstrate the involvement of extracellular Ca2+ in nsPEF-induced cell death. Extracellular Ca2+ was essential for necrosis and consequent poly(ADP-ribose) (PAR) formation in HeLa S3 cells. Treatment with a Ca2+ ionophore enhanced necrosis as well as PAR formation in nsPEF-exposed HeLa S3 cells. In the absence of extracellular Ca2+, HeLa S3 cells were less susceptible to nsPEFs and exhibited apoptotic proteolysis of caspase 3 and PARP-1. HeLa S3 cells retained the ability to undergo apoptosis even after nsPEF exposure but instead underwent necrosis, suggesting that necrosis is the preferential mode of cell death. In K562 and HEK293 cells, exposure to nsPEFs resulted in the formation of necrosis-associated PAR, whereas Jurkat cells exclusively underwent apoptosis independently of extracellular Ca2+. These observations demonstrate that the mode of cell death induced by nsPEFs is cell-type dependent and that extracellular Ca2+ is a critical factor for nsPEF-induced necrosis.
将培养的细胞暴露于纳秒级脉冲电场（nsPEF）会引发多种细胞反应，包括细胞外Ca2+内流和细胞死亡。最近，nsPEF被视为一种新型癌症治疗手段，但其分子作用机制仍有待充分阐明。在此，我们证明了细胞外Ca2+参与nsPEF诱导的细胞死亡。细胞外Ca2+对于HeLa S3细胞的坏死及随后的聚（ADP - 核糖）（PAR）形成至关重要。用Ca2+离子载体处理可增强nsPEF处理的HeLa S3细胞的坏死及PAR形成。在无细胞外Ca2+的情况下，HeLa S3细胞对nsPEF的敏感性较低，并表现出半胱天冬酶3和PARP - 1的凋亡性蛋白水解。HeLa S3细胞即使在暴露于nsPEF后仍保留凋亡能力，但却发生了坏死，这表明坏死是优先的细胞死亡方式。在K562和HEK293细胞中，暴露于nsPEF会导致坏死相关PAR的形成，而Jurkat细胞仅独立于细胞外Ca2+发生凋亡。这些观察结果表明，nsPEF诱导的细胞死亡模式具有细胞类型依赖性，并且细胞外Ca2+是nsPEF诱导坏死的关键因素。
