Arsenic affects homologous recombination and single‐strand annealing but not end‐joining pathways during DNA double‐strand break repair

Abstract

Arsenic is a carcinogen that can cause skin, lung, and bladder cancer. While DNA double‐strand breaks (DSBs) have been implicated in arsenic‐induced carcinogenesis, the exact mechanism remains unclear. In this study, we performed genetic analysis to examine the impact of arsenic trioxide (As2O3) on four different DSB repair pathways using the human pre‐B cell line Nalm‐6. Random integration analysis showed that As2O3 does not negatively affect non‐homologous end joining or polymerase theta‐mediated end joining. In contrast, chromosomal DSB repair analysis revealed that As2O3 decreases the efficiency of homologous recombination (HR) and, less prominently, single‐strand annealing. Consistent with this finding, As2O3 decreased gene‐targeting efficiency, owing to a significant reduction in the frequency of HR‐mediated targeted integration. To further verify the inhibitory effect of arsenic on HR, we examined cellular sensitivity to olaparib and camptothecin, which induce one‐ended DSBs requiring HR for precise repair. Intriguingly, we found that As2O3 significantly enhances sensitivity to those anticancer agents in HR‐proficient cells. Our results suggest that arsenic‐induced genomic instability is attributed to HR suppression, providing valuable insights into arsenic‐associated carcinogenesis and therapeutic options.

Altered Regulation of the Glucose Transporter GLUT3 in PRDX1 Null Cells Caused Hypersensitivity to Arsenite

“…Arsenite is known to induce ROS-mediated DNA damage in breast cancer cells, stimulate IκB phosphorylation, activate the transcription factor NF-κB and increase the c-Myc and HO-1 protein levels [35]. Since PRDX1 is a sensor of ROS and a regulator of intracellular ROS signalling pathways, the hypersensitivity of PRDX1 null cells to arsenite may be a result of either stress-induced cell death or the accumulation of DNA lesions [36,37]. PRDX1 has been shown to protect several signalling proteins, such as PTEN and AKT, from oxidation-induced inactivation and proteasomal degradation, as well as regulating the signalling of key transcription factors, such as NF-κB, c-Myc and the androgen receptor (AR) [38][39][40].…”

Characterization and regulation of cell cycle-independent noncanonical gene targeting

“…DR-GFP/SA-GFP reporter assays were performed as previously described 66 , 67 . Briefly, cells with the GFP reporter cassette (see Supplementary Methods for details) were transfected with 2 µg of pSceI, pSceI-Geminin, pSceI-Cdt1, or pmaxGFP (Lonza (Basel, Switzerland)) using the MaxCyte STX device.…”