Mitigating cisplatin resistance in ovarian cancer.

Epithelial Ovarian cancer (EOC) is the leading cause of gynecological cancer death in the USA. Recurrence rates are high after front-line platinum chemotherapy and most patients eventually die from platinum-resistant disease. P53 plays an important role in cellular response to platinum-DNA damage. It transcriptionally activates XPC, a platinum-DNA damage recognition protein in the global genome repair (GGR), sub-pathway of nucleotide excision repair (NER). The goal of this research is to investigate the effect of a novel combination of cisplatin, sodium arsenite (NaAs02) and hyperthermia (CPA 39 DC) on EOC cells with different p53 status. Human EOC cells were treated with cisplatin ± 20 IJM NaAs02 for 1 h at 37 or 39°C. NaAs02 ± hyperthermia selectively sensitized wild-type p53 EOC cells to cisplatin by suppressing XPC and enhancing cellular and DNA platinum accumulation. In contrast, only hyperthermia sensitized p53-mutated and p53-null EOC cells to cisplatin by enhancing cellular and DNA platinum accumulation. Cisplatin ± NaAs02 at 37 or 39°C induced pseudo-G1 associated apoptosis in p53 expressing cells. Co-treatment with HSP90 inhibitor 17-DMAG plus CPA 39°C greatly sensitized EOC cells by enhancing cellular platinum accumulation. In order to translate the in vitro findings in an in vivo model, metastatic ovarian cancer was established in nude mice by intraperitoneal injection of A2780/CP70 human EOC cells. Tumor bearing mice were perfused with 3 mg/kg body weight (BW) cisplatin ± 26 mg/kg BW NaAs02 for 1 h at 37 or 43°C using a murine intraperitoneal chemotherapy system developed in our laboratory. Cisplatin induced NER proteins XPC and XPA and suppressed mismatch repair protein MSH2 that is associated with resistance. However, co-treatment with NaAs02 at 37 or 43°C suppressed XPC, restored higher levels of MSH2 and enhanced tumor platinum uptake. Platinum and arsenic generally accumulated in systemic tissues during intraperitoneal lavage and decreased 24 h after perfusion. In conclusion, CPA 39 °C alone or combined with 17-DMAG has the potential to sensitize EOC to cisplatin by attenuating NER, activating mismatch repair, enhancing tumor platinum accumulation and activating apoptotic cell death

Sodium arsenite and hyperthermia modulate cisplatin-DNA damage responses and enhance platinum accumulation in murine metastatic ovarian cancer xenograft after hyperthermic intraperitoneal chemotherapy (HIPEC)

<p>Abstract</p> <p>Background</p> <p>Epithelial ovarian cancer (EOC) is the leading cause of gynecologic cancer death in the USA. Recurrence rates are high after front-line therapy and most patients eventually die from platinum (Pt) - resistant disease. Cisplatin resistance is associated with increased nucleotide excision repair (NER), decreased mismatch repair (MMR) and decreased platinum uptake. The objective of this study is to investigate how a novel combination of sodium arsenite (NaAsO₂) and hyperthermia (43°C) affect mechanisms of cisplatin resistance in ovarian cancer.</p> <p>Methods</p> <p>We established a murine model of metastatic EOC by intraperitoneal injection of A2780/CP70 human ovarian cancer cells into nude mice. We developed a murine hyperthermic intraperitoneal chemotherapy model to treat the mice. Mice with peritoneal metastasis were perfused for 1 h with 3 mg/kg cisplatin ± 26 mg/kg NaAsO₂at 37 or 43°C. Tumors and tissues were collected at 0 and 24 h after treatment.</p> <p>Results</p> <p>Western blot analysis of p53 and key NER proteins (ERCC1, XPC and XPA) and MMR protein (MSH2) suggested that cisplatin induced p53, XPC and XPA and suppressed MSH2 consistent with resistant phenotype. Hyperthermia suppressed cisplatin-induced XPC and prevented the induction of XPA by cisplatin, but it had no effect on Pt uptake or retention in tumors. NaAsO₂prevented XPC induction by cisplatin; it maintained higher levels of MSH2 in tumors and enhanced initial accumulation of Pt in tumors. Combined NaAsO₂and hyperthermia decreased cisplatin-induced XPC 24 h after perfusion, maintained higher levels of MSH2 in tumors and significantly increased initial accumulation of Pt in tumors. ERCC1 levels were generally low except for NaAsO₂co-treatment with cisplatin. Systemic Pt and arsenic accumulation for all treatment conditions were in the order: kidney > liver = spleen > heart > brain and liver > kidney = spleen > heart > brain respectively. Metal levels generally decreased in systemic tissues within 24 h after treatment.</p> <p>Conclusion</p> <p>NaAsO₂and/or hyperthermia have the potential to sensitize tumors to cisplatin by inhibiting NER, maintaining functional MMR and enhancing tumor platinum uptake.</p

Arsenic Disruption of DNA Damage Responses—Potential Role in Carcinogenesis and Chemotherapy

Arsenic is a Class I human carcinogen and is widespread in the environment. Chronic arsenic exposure causes cancer in skin, lung and bladder, as well as in other organs. Paradoxically, arsenic also is a potent chemotherapeutic against acute promyelocytic leukemia and can potentiate the cytotoxic effects of DNA damaging chemotherapeutics, such as cisplatin, in vitro. Arsenic has long been implicated in DNA repair inhibition, cell cycle disruption, and ubiquitination dysregulation, all negatively impacting the DNA damage response and potentially contributing to both the carcinogenic and chemotherapeutic potential of arsenic. Recent studies have provided mechanistic insights into how arsenic interferes with these processes including disruption of zinc fingers and suppression of gene expression. This review discusses these effects of arsenic with a view toward understanding the impact on the DNA damage response

Cutaneous effects of in utero and lactational exposure of C57BL/6J mice to 2,3,7,8-tetrachlorodibenzo-p-dioxin

To determine the cutaneous effects of in utero and lactational exposure to the AHR ligand 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), pregnant C57BL/6J mice were exposed by gavage to a vehicle or 5 _g TCDD/kg body weight at embryonic day 12 and epidermal barrier formation and function were studied in their offspring from postnatal day 1 (P1) through adulthood. TCDDexposed pups were born with acanthosis. This effect was AHR-dependent and subsided by P6 with no evidence of subsequent inflammatory dermatitis. The challenge of adult mice with MC903 showed similar inflammatory responses in control and treated animals, indicating no long-term immunosuppression to this chemical. Chloracne-like sebaceous gland hypoplasia and cyst formation were observed in TCDD-exposed P21 mice, with concomitant microbiome dysbiosis. These effects were reversed by P35. CYP1A1 and CYP1B1 expression in the skin was increased in the exposed mice until P21, then declined. Both CYP proteins co-localized with LRIG1-expressing progenitor cells at the infundibulum. CYP1B1 protein also co-localized with a second stem cell niche in the isthmus. These results indicate that this exposure to TCDD causes a chloracne-like effect without inflammation. Transient activation of the AhR, due to the shorter half-life of TCDD in mice, likely contributes to the reversibility of these effects

Effects of in utero exposure of C57Bl/6J mice to 2,3,7,8-tetrachlorodibenzop-dioxin on epidermal permeability barrier development and function

Results: A skin permeability assay showed that TCDD accelerated the development of the EPB, beginning at E15. This was accompanied by a significant decrease in transepidermal water loss (TEWL), enhanced stratification, and formation of the stratum corneum (SC). The levels of several ceramides were significantly increased at E15 and E16. PND1 histology revealed TCDD-induced acanthosis and epidermal hyperkeratosis. This was accompanied by disrupted epidermal tight junction (TJ) function, with increased dye leakage at the terminal claudin-1–staining TJs of the stratum granulosum. Because the animals did not have enhanced rates of TEWL, a commonly observed phenotype in animals with TJ defects, we performed tape-stripping. Removal of most of the SC resulted in a significant increase in TEWL in TCDD-exposed PND1 pups compared with their control group