Department of Pharmaceutical Sciences, College of Pharmacy, University of New Mexico, 1 University of New Mexico, Albuquerque, NM 87131, United States of America.
Department of Pharmaceutical Sciences, College of Pharmacy, University of New Mexico, 1 University of New Mexico, Albuquerque, NM 87131, United States of America; Department of Chemistry and Biochemistry, Ohio State University, Columbus, OH 43210, United States of America.
Toxicol Appl Pharmacol. 2022 Jan 1;434:115799. doi: 10.1016/j.taap.2021.115799. Epub 2021 Nov 16.
Arsenic is a naturally occurring element present in food, soil and water and human exposure is associated with increased cancer risk. Arsenic inhibits DNA repair at low, non-cytotoxic concentrations and amplifies the mutagenic and carcinogenic impact of other DNA-damaging agents, such as ultraviolet radiation (UVR). Arsenic exposure leads to oxidation of zinc coordinating cysteine residues, zinc loss and decreased activity of the DNA repair protein poly(ADP)ribose polymerase (PARP)-1. Because arsenic stimulates NADPH oxidase (NOX) activity leading to generation of reactive oxygen species (ROS), the goal of this study was to investigate the role of NOX in arsenic-induced inhibition of PARP activity and retention of DNA damage. NOX involvement in the arsenic response was assessed in vitro and in vivo. Keratinocytes were treated with or without arsenite, solar-simulated UVR, NOX inhibitors and/or isoform specific NOX siRNA. Knockdown or inhibition of NOX decreased arsenite-induced ROS, PARP-1 oxidation and DNA damage retention, while restoring arsenite inhibition of PARP-1 activity. The NOX2 isoform was determined to be the major contributor to arsenite-induced ROS generation and DNA damage retention. In vivo DNA damage was measured by immunohistochemical staining and analysis of dorsal epidermis sections from C57BI/6 and p91phox knockout (NOX2) mice. There was no significant difference in solar-simulated UVR DNA damage as detected by percent PH2AX positive cells within NOX2 mice versus control. In contrast, arsenite-dependent retention of UVR-induced DNA damage was markedly reduced. Altogether, the in vitro and in vivo findings indicate that NOX is involved in arsenic enhancement of UVR-induced DNA damage.
砷是一种存在于食物、土壤和水中的天然元素，人类接触砷会增加患癌症的风险。砷在低浓度、非细胞毒性浓度下抑制 DNA 修复，并放大其他 DNA 损伤剂（如紫外线辐射 UVR）的致突变和致癌作用。砷暴露会导致锌配位半胱氨酸残基氧化、锌丢失和 DNA 修复蛋白多聚（ADP-核糖）聚合酶 1（PARP-1）活性降低。由于砷刺激 NADPH 氧化酶（NOX）活性导致活性氧（ROS）的产生，因此本研究的目的是研究 NOX 在砷诱导的 PARP 活性抑制和 DNA 损伤保留中的作用。在体外和体内评估了 NOX 在砷反应中的作用。用亚砷酸盐、模拟太阳 UVR、NOX 抑制剂和/或同工型特异性 NOX siRNA 处理角质形成细胞。NOX 的敲低或抑制降低了亚砷酸盐诱导的 ROS、PARP-1 氧化和 DNA 损伤保留，同时恢复了亚砷酸盐对 PARP-1 活性的抑制。NOX2 同工型被确定为砷诱导的 ROS 产生和 DNA 损伤保留的主要贡献者。通过免疫组织化学染色和 C57BI/6 和 p91phox 敲除（NOX2）小鼠背部表皮切片分析测量体内 DNA 损伤。NOX2 小鼠与对照相比，通过 PH2AX 阳性细胞的百分比检测到的模拟太阳 UVR DNA 损伤没有显着差异。相比之下，砷依赖性 UVR 诱导的 DNA 损伤保留明显减少。总之，体外和体内的研究结果表明，NOX 参与了砷增强 UVR 诱导的 DNA 损伤。
