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Human lung cancer cell lines A549 and A549/DDP, and ovarian cancer cell lines SKOV3 and SKOV3/DDP were subjected to thioridazine (Thio), cisplatin, or the combination; A549/DDP and SKOV3/DDP were the cisplatin-resistant sublines. Cell viability, apoptosis, and cell cycle were detected; the mitochondrial membrane potential and proteins related to mitochondrial apoptosis were determined. Thio induced cell death, and the combination of Thio and cisplatin led to the highest percentage of dead cells in four cells lines. Thio and the combined modality led to cell apoptosis by inducing G 0 /G 1 arrest. The collapse of mitochondrial membrane potential, activation of caspase 9, upregulation of Bax protein, and downregulation of Bcl-2 protein demonstrated that apoptosis was mitochondria dependent. These data indicated that Thio could be used to modulate cisplatin-based chemotherapeutic regimen in lung and ovary cancers.

Chemoresistance is a challenge for management of ovarian cancer, and therefore the response of resistant cells to nanosecond electric pulses (nsEP) was explored. Human ovarian cancer cell line COC1 and the cisplatin-resistant subline COC1/DDP were subjected to nsEP (32 ns, 10 kV/cm, 10 Hz pulse repletion frequency, and 10 min exposure duration), and then the cellular responses were followed. The percentages of dead cells and of comet-formed cells in the alkaline assay displayed two peak levels (i.e., 2 and 8 h after nsEP exposure), with the highest value noted at 8 h; the percentage of comet-formed cells in the neutral assay was increased at 8 h; the apoptotic percentage was increased at 8 h, with collapse of the mitochondrial membrane potential and the activation of caspase-3 and caspase-9. The comet assay demonstrated DNA single-strand break at 2 h and double-strand break at 8 h. nsEP resulted in lower cytotoxicity in COC1/DDP cells compared with COC1 cells. These findings indicated that nsEP induced early and late phases of DNA damage and cell death, and these two types of cell death may have distinct applications to treatments of chemoresistant ovarian cancers.

Clinical implications of the BRCA2 expression level on treatments of ovarian cancer are controversial. Here, we demonstrated that platinum-resistant cancer had a higher percentage of high BRCA2 level (87.5% vs 43.6%, P  = 0.001), and that patients with a low BRCA2 level in cancer tissues had longer progression-free survival (with a median time of 28.0 vs 12.0 months, P  < 0.001) and platinum-free duration (with a median time of 19.0 vs 5.0 months, P  < 0.001) compared with those with a high BRCA2 level. In human ovarian cancer cell lines CAOV-3 and ES-2, cisplatin induced an upregulation of the RAD51 protein, which was inhibited after silencing BRCA2 ; silencing BRCA2 enhanced the action of cisplatin in vitro and in vivo Knockdown of BRCA2 promoted cisplatin-induced autophagy. Interestingly, the autophagy blocker chloroquine enhanced cisplatin in BRCA2-silenced cells accompanied by an increase in apoptotic cells, which did not occur in BRCA2-intact cells; chloroquine enhanced the efficacy of cisplatin against BRCA2-silenced CAOV-3 tumors in vivo , with an increase in LC3-II level in tumor tissues. Sensitization of cisplatin was also observed in BRCA2-silenced CAOV-3 cells after inhibiting ATG7, confirming that chloroquine modulated the sensitivity via the autophagy pathway. These data suggest that a low BRCA2 level can predict better platinum sensitivity and prognosis, and that the modulation of autophagy can be a chemosensitizer for certain cancers., (© 2018 Society for Endocrinology.)

Cisplatin resistance is a challenge in the treatment of ovarian cancer. The aim of this study was to explore if ultrasound can overcome chemoresistance and enhance chemosensitization due to cyclosporin A. Ultrasound and/or cyclosporin A were employed to overcome cisplatin resistance in human ovarian cancer cell line COC1/DDP. Mechanisms were explored from the perspective of: DNA damage, intracellular platinum level, detoxification, and genes related to drug efflux and DNA repair. In vivo therapeutic efficacy was validated in a short-term model (subrenal cell-clot transplantation) in mice and the survival benefit was investigated in an orthotopic cancer model in mice using HO-8910PM cells. The findings were: (i) ultrasound enhanced the effect of cisplatin leading to a lower cell-survival rate (IC50 decreased from 3.19 to 0.35 μg/ml); (ii) ultrasound enhanced cisplatin via direct (increasing the intercellular level of active platinum) and indirect (decreasing the glutathione level, and expression of LRP and ERCC1 genes) mechanisms that intensified cisplatin-induced DNA damage, thus enhancing cell apoptosis and necrosis; (iii) cisplatin followed by ultrasound led to small tumor sizes in the short-term model without exacerbation of the systemic toxicity, and prolonged the survival times in the orthotopic model; and (iv) ultrasound synergized the sensitization due to cyclosporin A in vitro and in vivo. These data demonstrated that ultrasound combined with cyclosporin A overcame cisplatin resistance in ovarian cancer., (Copyright © 2015 Elsevier B.V. All rights reserved.)

Indoleamine 2,3-dioxygenase 1 (IDO1) is a heme-containing dioxygenase that may play a part in chemoresistance in ovarian cancer. However, its role in cisplatin (DDP) resistance is unclear. Here, the expression level of IDO1 in tumors in platinum-resistant (n = 22) and -sensitive (n = 46) ovarian cancer patients was determined, and then how IDO1 modulated DDP resistance was explored in vitro and in vivo. The IDO1 expression level in platinum-resistant patients was higher than that in -sensitive patients, and a higher IDO1 level was correlated with poor prognosis in type II cancer patients. Up-regulating IDO1 decreased DDP-induced apoptosis in SKOV3 cells via inhibiting the ROS/p53 cell-death pathway, thereby attenuating cytotoxicity of DDP. Silencing IDO1 enhanced p53-dependent apoptosis by increasing ROS accumulation, thereby enhancing DDP against SKOV3 cells. Down-knocking IDO1 augmented the action of DDP in vivo. These data demonstrated that silencing IDO1 enhanced the efficacy of DDP by intensifying p53-dependent apoptosis, and that targeting IDO1 can be a strategy to modulate DDP-based chemotherapy for epithelial ovarian cancer. [ABSTRACT FROM AUTHOR]

Thioridazine was used to sensitize cisplatin against cisplatin-resistant human lung cancer cells. Cells received thioridazine, cisplatin, or both drugs (the combination). Thioridazine synergized cisplatin to increase percentages of dead and apoptotic cells. DNA damage was detected using the comet assays; the combination led to the highest alkaline- and neutral-comet percentages, demonstrating exacerbation of both single- and double-strand breaks. After thioridazine treatment, levels of glutathione, and BRCA2, RAD51, and ERCC1 proteins were decreased. These data manifested that thioridazine decreased the capacities of detoxification and DNA repair, thereby enhancing cisplatin-induced DNA damage in resistant cells. [ABSTRACT FROM AUTHOR]

Purpose: To explore methodological modifications in the detection of DNA damage in sonochemotherapy for cisplatin-resistant human ovarian cancer cells using the comet assays. Materials and methods: Chemoresistant cells COC1/DDP were subjected to sonochemotherapy and DNA damage detected with the alkaline and neutral comet assays. Results: In the alkaline assay, the percentage of comets formed was less than that of dead cells, and most values for the percentage of comets formed were < 5% when using the default value to identify comets, showing an underestimation. These values were corrected when adjusting the threshold to the 95th percentile in control cells. In the neutral assay, this modification was not needed. Tail length (TL), tail moment (TM) and Olive tail moment (OTM) dramatically varied between comets. The 75th percentiles of TL, TM and OTM in the alkaline assay, and 90th percentiles in the neutral assay, correlated with the percentage of comets formed, thereby reflecting the temporal shift in DNA damage. Quantification of the interaction using the percentage of comets formed was consistent with that using the percentage of dead cells. Conclusions: The percentage of comets formed can be used to assess DNA damage in sonochemotherapy against chemoresistant cells when adjusting the threshold. [ABSTRACT FROM AUTHOR]

Abstract: Human ovarian cancer cells COC1 and COC1/DDP (cisplatin-resistant subline) were exposed to 6kV/cm nanosecond electric pulses (nsEP) with a pulse length of 8, 16 or 24ns. 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 24ns, p =0.0150) and more survival (22.42% vs. 13.19% at 24ns, 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. [Copyright &y& Elsevier]