title: Nanosecond electric pulses induce DNA breaks in cisplatin-sensitive and -resistant human ovarian cancer cells.
abstract: Human ovarian cancer cells COC1 and COC1/DDP (cisplatin-resistant subline) were exposed to 6 kV/cm nanosecond electric pulses (nsEP) with a pulse length of 8, 16 or 24 ns. The potential in a subcellular unit was calculated using a multilayer dielectric spherical model, and area under the voltage-time curves (AUC) integrated with a lower limit of 0.2V. Cell viability was determined, and double-stand and total DNA breaks detected with the neutral and alkaline comet assays. nsEP evoked a higher voltage and AUC in nucleoplasm, and the levels in COC1 cells was just above those in COC1/DDP cells. Comets only appeared in the alkaline assay demonstrating single-stand DNA break. Fewer DNA break (16.51% vs. 35.13% at 24 ns, p=0.0150) and more survival (22.42% vs. 13.19% at 24 ns, p=0.0015) occurred in COC1/DDP cells despite an equal electric energy and almost equal cell sizes. 24-ns EP led to higher rates of cell-death and comet. The comet rate correlated with cell-death fraction in either cell line (r=0.5701, p=0.0135; r=0.5110, p=0.0302). There was no a correlation between the tail length, tail moment or Olive tail moment and cell-death rate. The data showed that response of chemosensitive cells differed from that of chemoresistant cells and DNA damage contributed to percent of cell death.
authors.affiliation: Laboratory of Obstetrics and Gynecology, The Second Affiliated Hospital, Chongqing Medical University, Chongqing 400010, China.
authors.forename: Lingjuan
authors.initials: L
authors.lastname: Linghu
authors.forename: Yafang
authors.initials: Y
authors.lastname: Tan
authors.forename: Yi
authors.initials: Y
authors.lastname: Lou
authors.forename: Lina
authors.initials: L
authors.lastname: Hu
authors.forename: Hongchun
authors.initials: H
authors.lastname: Yang
authors.forename: Tinghe
authors.initials: T
authors.lastname: Yu
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology; D017209:Apoptosis; D045744:Cell Line, Tumor; D002945:Cisplatin / Q000494:pharmacology; D020552:Comet Assay; D053904:DNA Breaks, Single-Stranded; D019008:Drug Resistance, Neoplasm; D004558:Electric Stimulation; D005260:Female; D006801:Humans; D010051:Ovarian Neoplasms / Q000235:genetics*
chemical_list: D000970:Antineoplastic Agents; D002945:Cisplatin