Medical Toxicology Commons^™

Epigenetic Dysregulations In Arsenic-Induced Carcinogenesis, Ranakul Islam, Lei Zhao, Yifang Wang, Grace Lu-Yao, Ling-Zhi Liu

Department of Medical Oncology Faculty Papers

Arsenic is a crucial environmental metalloid whose high toxicity levels negatively impact human health. It poses significant health concerns to millions of people in developed and developing countries such as the USA, Canada, Bangladesh, India, China, and Mexico by enhancing sensitivity to various types of diseases, including cancers. However, how arsenic causes changes in gene expression that results in heinous conditions remains elusive. One of the proposed essential mechanisms that still has seen limited research with regard to causing disease upon arsenic exposure is the dysregulation of epigenetic components. In this review, we have extensively summarized current discoveries in arsenic-induced …

Assessing The Role Of Arsenite In Disrupting The Egfr Signaling Axis., Christine Kim

Electronic Theses and Dissertations

The epidermal growth factor receptor (EGFR) is a receptor tyrosine kinase localized on the cell surface. Overexpression of EGFR has been used as biomarkers for many different types of cancers, including lung cancer. There is a strong association between arsenic and lung cancer development, although the mechanism is unclear. We hypothesize that chronic exposure of “a physiologically relevant” level of arsenite disrupts the EGFR endocytic trafficking. The goal of this project is to identify molecular mechanisms and roles of chronic arsenite-induced EGFR overexpression in lung cancer development. A non-malignant human bronchial epithelial cell line, Beas-2B cells were exposed to 100 …

Nucleotide Excision Repair: Impacts Of Environmental Carcinogens And Its Role In Cancer Susceptibility In Appalachian Kentucky, Nathaniel C. Holcomb

Theses and Dissertations--Toxicology and Cancer Biology

Lung cancer is a particularly devastating disease, accounting for the most deaths among all cancer types in the United States. Despite a reduction in the country’s smoking rates, cigarette smoking remains the number one risk factor for lung cancer. Additionally arsenic exposure, which occurs primarily through contaminated drinking water in the U.S., is associated with increased lung cancer incidence. The nucleotide excision repair (NER) pathway is critical for maintenance of genomic fidelity, removing DNA lesions that could otherwise promote DNA mutations and drive carcinogenesis. Tobacco smoking introduces significant amounts of DNA damage and produces characteristic DNA mutations found in lung …

Toxic Environmental Exposures And Kidney Health In Children., Darcy K. Weidemann, Virginia M. Weaver, Jeffrey J. Fadrowski

Manuscripts, Articles, Book Chapters and Other Papers

High-level exposures to a number of agents are known to have direct nephrotoxic effects in children. A growing body of literature supports the hypothesis that chronic, relatively low-level exposure to various nephrotoxicants may also increase the risk for chronic kidney disease (CKD) or accelerate its progression. In this review we highlight several environmental nephrotoxicants and their association with CKD in children and adolescents. We also discuss unique epidemiological challenges in the use of kidney biomarkers in environmental nephrotoxicology.

Arsenic Inhibits Dna Mismatch Repair By Promoting Egfr Expression And Pcna Phosphorylation, Dan Tong, Janice Ortega, Christine Kim, Jian Huang, Liya Gu, Guo-Min Li

Toxicology and Cancer Biology Faculty Publications

Both genotoxic and non-genotoxic chemicals can act as carcinogens. However, while genotoxic compounds lead directly to mutations that promote unregulated cell growth, the mechanism by which non-genotoxic carcinogens lead to cellular transformation is poorly understood. Using a model non-genotoxic carcinogen, arsenic, we show here that exposure to arsenic inhibits mismatch repair (MMR) in human cells, possibly through its ability to stimulate epidermal growth factor receptor (EGFR)-dependent tyrosine phosphorylation of proliferating cellular nuclear antigen (PCNA). HeLa cells exposed to exogenous arsenic demonstrate a dose- and time-dependent increase in the levels of EGFR and tyrosine 211-phosphorylated PCNA. Cell extracts derived from arsenic-treated …

Preliminary Analysis Of In Utero Low-Level Arsenic Exposure And Fetal Growth Using Biometric Measurements Extracted From Fetal Ultrasound Reports, Matthew A. Davis, John Higgins, Zhigang Li, Diane Gilbert-Diamond, Emily R. Baker, Amar Das, Margaret R. Karagas

Dartmouth Scholarship

Background: Early life exposure to arsenic is associated with decreased birth weight in highly exposed populations but little is known about effects of low-level arsenic exposure on growth in utero.

Methods: Using a sample of 272 pregnancies from New Hampshire we obtained biometric measurements directly from fetal ultrasound reports commonly found in electronic medical records. We used information extraction methods to develop and validate an automated approach for mining biometric measurements from the text of clinical reports. As a preliminary analysis, we examined associations between in utero low-level arsenic exposure (as measured by maternal urinary arsenic concentration) and fetal growth …

Arsenic Targets Neural Plate Border Specifier Cells In P19 Cells, Christopher Mccoy

All Theses

Epidemiological studies have shown that arsenic exposure during early embryogenesis can cause reduced weight gain and neurological deficits later on in life. In addition, in vitro and in vivo studies have indicated that arsenic suppresses neurogenesis and myogenesis. The exact mechanism of how arsenic causes these undesired developmental outcomes is poorly understood, however both skeletal muscle and sensory neuron development require the Wnt/β-catenin signaling pathway to initiate the specific differentiation of precursor cells. We were interested in determining the target cell population of arsenic and its metabolites. Arsenic's metabolites were of interest because they have been shown to be more …

Diet And Toenail Arsenic Concentrations In A New Hampshire Population With Arsenic-Containing Water, Kathryn L. Cottingham, Roxanne Karimi, Joann F. Gruber, M Scot Zens, Vicki Sayarath, Carol L. Folt, Tracy Punshon, J. Steven Morris, Margaret R. Karagas

Dartmouth Scholarship

Background: Limited data exist on the contribution of dietary sources of arsenic to an individual's total exposure, particularly in populations with exposure via drinking water. Here, the association between diet and toenail arsenic concentrations (a long-term biomarker of exposure) was evaluated for individuals with measured household tap water arsenic. Foods known to be high in arsenic, including rice and seafood, were of particular interest.

Methods: Associations between toenail arsenic and consumption of 120 individual diet items were quantified using general linear models that also accounted for household tap water arsenic and potentially confounding factors (e.g., age, caloric intake, sex, smoking) …

Associations Between Toenail Arsenic Concentration And Dietary Factors In A New Hampshire Ppopulation, Joann F. Gruber, Margaret R. Karagas, Diane Gilbert-Diamond, Pamela J. Bagley, M Scot Zens, Vicki Sayarath, Tracy Punshon, J Steven Morris, Kathryn L. Cottingham

Dartmouth Scholarship

Background: Dietary factors such as folate, vitamin B12, protein, and methionine are important for the excretion of arsenic via one-carbon metabolism in undernourished populations exposed to high levels of arsenic via drinking water. However, the effects of dietary factors on toenail arsenic concentrations in well-nourished populations exposed to relatively low levels of water arsenic are unknown.

Methods: As part of a population-based case-control study of skin and bladder cancer from the USA, we evaluated relationships between consumption of dietary factors and arsenic concentrations in toenail clippings. Consumption of each dietary factor was determined from a validated food frequency questionnaire. We …

Rice Consumption Contributes To Arsenic Exposure In Us Women, Diane Gilbert-Diamond, Kathryn L. Cottingham, Joann F. Gruber, Tracy Punshon, Vicki Sayarath, A. Jay Gandolfi, Emily R. Baker, Brian P. Jackson, Carol L. Folt, Margaret R. Karagas

Dartmouth Scholarship

Emerging data indicate that rice consumption may lead to potentially harmful arsenic exposure. However, few human data are available, and virtually none exist for vulnerable periods such as pregnancy. Here we document a positive association between rice consumption and urinary arsenic excretion, a biomarker of recent arsenic exposure, in 229 pregnant women. At a 6-mo prenatal visit, we collected a urine sample and 3-d dietary record for water, fish/seafood, and rice. We also tested women's home tap water for arsenic, which we combined with tap water consumption to estimate arsenic exposure through water. Women who reported rice intake (n …