Arsenic exposure is associated with significant upper tract urothelial carcinoma health care needs and elevated mortality rates

Molecular and cell phenotype programs in oral epithelial cells directed by co-exposure to arsenic and smokeless tobacco

Chronic arsenic exposure can lead to various health issues, including cancer. Concerns have been mounting about the enhancement of arsenic toxicity through co-exposure to various prevalent lifestyle habits. Smokeless tobacco products are commonly consumed in South Asian countries, where their use frequently co-occurs with exposure to arsenic from contaminated groundwater. To decipher the in vitro molecular and cellular responses to arsenic and/or smokeless tobacco, we performed temporal multi-omics analysis of the transcriptome and DNA methylome remodelling in exposed hTERT-immortalized human normal oral keratinocytes (NOK), as well as arsenic and/or smokeless tobacco genotoxicity and mutagenicity investigations in NOK cells and in human p53 knock-in murine embryonic fibroblasts (Hupki MEF). RNAseq results from acute exposures to arsenic alone and in combination with smokeless tobacco extract revealed upregulation of genes with roles in cell cycle changes, apoptosis and inflammation responses. This was in keeping with global DNA hypomethylation affecting genes involved in the same processes in response to chronic treatment in NOK cells. At the phenotypic level, we observed a dose-dependent decrease in NOK cell viability, induction of DNA damage, cell cycle changes and increased apoptosis, with the most pronounced effects observed under arsenic and SLT co-exposure conditions. Live-cell imaging experiments indicated that the DNA damage likely resulted from induction of apoptosis, an observation validated by a lack of exome-wide mutagenesis in response to chronic exposure to arsenic and/or smokeless tobacco. In sum, our integrative omics study provides novel insights into the acute and chronic responses to arsenic and smokeless tobacco (co-)exposure, with both types of responses converging on several key mechanisms associated with cancer hallmark processes. The generated rich catalogue of molecular programs in oral cells regulated by arsenic and smokeless tobacco (co-)exposure may provide bases for future development of biomarkers for use in molecular epidemiology studies of exposed populations at risk of developing oral cancer.

Low-to-Moderate Arsenic Exposure and Urothelial Tract Cancers with a Long Latent Period of Follow-Up in an Arseniasis Area

BACKGROUND

Arsenic exposure can cause adverse health effects. The effects of long-term low-to-moderate exposure and methylations remain unclear.

OBJECTIVE

This study aims to examine the association between low-to-moderate arsenic exposure and urothelial tract cancers while considering the effects of methylation capacity.

METHODS

In this study, 5,811 participants were recruited from an arseniasis area in Taiwan for inorganic arsenic metabolite analysis. This follow-up study was conducted between August 1995 and December 2017. We identified 85 urothelial tract cancers in these participants, including 49 bladder and 36 upper urothelial tract cancer cases. A Cox proportional hazards model was employed.

RESULTS

The analyses revealed a significant association between concentrations of inorganic arsenic in water > 100 ug/L and bladder cancer occurrence, with a hazard ratio (HR) of 4.88 (95% CI 1.35-17.61). A monotonic trend was observed between concentrations of inorganic arsenic in water (from 0 to > 100 ug/L) and the incidence of urothelial tract cancer, including bladder cancer (p < 0.05) and upper urothelial tract cancers (p < 0.05). Participants with a lower primary methylation index or higher secondary methylation index had a prominent effect.

CONCLUSIONS

Rigorous regulations and active interventions should be considered for populations with susceptible characteristics.

Recent advancements in toxicology, modern technology for detection, and remedial measures for arsenic exposure: review

Arsenic toxicity has become a major global health concern for humans and animals due to extensive environmental and occupational exposure to arsenic-contaminated water, air, soil, and plant and animal origin food. It has a wide range of detrimental effects on animals, humans, and the environment. As a result, various experimental and clinical studies were undertaken and are undergoing to understand its source of exposures, pathogenesis, identify key biomarkers, the medical and economic impact on affected populations and ecosystems, and their timely detection and control measures. Despite these extensive studies, no conclusive information for the prevention and control of arsenic toxicity is available, owing to complex epidemiology and pathogenesis, including an imprecise approach and repetitive work. As a result, there is a need for literature that focuses on recent studies on the epidemiology, pathogenesis, detection, and ameliorative measures of arsenic toxicity to assist researchers and policymakers in the practical future planning of research and community control programs. According to the preceding viewpoint, this review article provides an extensive analysis of the recent progress on arsenic exposure to humans through the environment, livestock, and fish, arsenic toxicopathology, nano-biotechnology-based detection, and current remedial measures for the benefit of researchers, academicians, and policymakers in controlling arsenic eco-toxicology and directing future research. Arsenic epidemiology should therefore place the greatest emphasis on the prevalence of different direct and indirect sources in the afflicted areas, followed by control strategies.