Although the molecular mechanism of arsenic-induced carcinogenesis remains to be investigated, reactive oxygen species (ROS) generated by arsenic are considered to be important. Arsenic-generated ROS could cause DNA damage, lipid peroxidation and protein modification, leading to various carcinogenic responses. Our preliminary studies have shown that the capacity of ROS generation induced by arsenic is substantially reduced in arsenic-transformed human lung bronchial epithelial (BEAS-2B) cells relative to the non-transformed cells. Such a reduction in ROS generation endows cells with premalignant features, including rapid growth. Arsenic- transformed cells exhibit a decreased apoptosis (apoptosis resistance) upon arsenic exposure. This proposal hypothesizes that due to a low potency of ROS generation, arsenic-transformed cells develop apoptosis resistance and increased cell survival, contributing to the overall mechanism of arsenic-induced carcinogenesis.
Three aims are proposed to test this hypothesis.
Aim 1 will investigate the mechanism of decreased ROS generation in the arsenic-transferred cells. We will investigate whether impairment of the ROS generating pathway is responsible for a low level of arsenic-induced ROS generation in arsenic transformed BEAS-2B cells. We will also investigate whether the increased level of antioxidant enzymes in transformed cells contributes to the decreased level of ROS generation. The completion of this aim will establish the mechanism of decreased ROS generation in arsenic-transformed cells.
Aim 2 will investigate the role of reduced ROS generation in apoptosis resistance of arsenic-transformed cells. We investigate (a) whether reduced ROS generation of arsenic- transformed cells is responsible for apoptosis resistance in arsenic-transformed cells;(b) whether arsenic- transformed cells have higher antioxidant activities of SOD and catalase than their passage-matched control cells;(c) whether knock-down of antioxidant enzymes or overexpressing NADPH oxidase in the transformed cells increases ROS generation and enhances apoptosis in response to arsenic stimulation;(d) whether knocking down of Bcl-2 increases apoptosis of arsenic-transformed cells;and (e) whether arsenic- transformed cell will show fast growth and enhanced invasion and migration due to the decreased ROS generation and apoptosis resistance. Overall, this aim will demonstrate the role of ROS in apoptosis resistance of arsenic-transformed cells.
Aim 3 will investigate the arsenic-transformed cells-induced tumorigenesis and the role of apoptosis. We will investigate the role of apoptosis resistance in tumorigenesis of arsenic-transformed cells. We will also investigate the roles of ROS and apoptosis regulatory proteins, Bcl-2, in arsenic-transformed cells-induced tumorigenesis using both skin tumorigenesis model and orthotopic lung cancer model. It is expected that the increase of apoptosis of arsenic-transformed cells by Bcl-2 knockdown will decrease tumor growth. Similarly, alterations in the ROS generating capacity of the cells, i.e., by ectopic overexpression and knockdown of the ROS-scavenging and producing enzymes, will have an effect on tumorigenesis of arsenic-transformed cells.

Public Health Relevance

Health effects of chronic exposure to arsenic are one of the major health concerns. The present study will investigate the mechanism of arsenic-induced carcinogenesis with a focus on decreased generation of reactive oxygen species and apoptosis resistance in arsenic transformed cells. The results will help understand the mechanism of arsenic carcinogenesis and to develop preventive strategy.

Agency
National Institute of Health (NIH)
Institute
National Institute of Environmental Health Sciences (NIEHS)
Type
Research Project (R01)
Project #
1R01ES020870-01
Application #
8219306
Study Section
Cancer Etiology Study Section (CE)
Program Officer
Thompson, Claudia L
Project Start
2012-01-15
Project End
2016-10-31
Budget Start
2012-01-15
Budget End
2012-10-31
Support Year
1
Fiscal Year
2012
Total Cost
$334,125
Indirect Cost
$109,125
Name
University of Kentucky
Department
Pharmacology
Type
Schools of Medicine
DUNS #
939017877
City
Lexington
State
KY
Country
United States
Zip Code
40506
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Son, Young-Ok; Pratheeshkumar, Poyil; Wang, Yuting et al. (2017) Protection from Cr(VI)-induced malignant cell transformation and tumorigenesis of Cr(VI)-transformed cells by luteolin through Nrf2 signaling. Toxicol Appl Pharmacol 331:24-32
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Wang, Lei; Wise, James T F; Zhang, Zhuo et al. (2016) Progress and prospects of reactive oxygen species in metal carcinogenesis. Curr Pharmacol Rep 2:178-186
Roy, Ram Vinod; Pratheeshkumar, Poyil; Son, Yong-Ok et al. (2016) Different roles of ROS and Nrf2 in Cr(VI)-induced inflammatory responses in normal and Cr(VI)-transformed cells. Toxicol Appl Pharmacol 307:81-90
Wang, Lei; Fan, Jia; Hitron, John Andrew et al. (2016) Cancer Stem-Like Cells Accumulated in Nickel-Induced Malignant Transformation. Toxicol Sci 151:376-87
Zhang, Zhuo; Pratheeshkumar, Poyil; Budhraja, Amit et al. (2015) Role of reactive oxygen species in arsenic-induced transformation of human lung bronchial epithelial (BEAS-2B) cells. Biochem Biophys Res Commun 456:643-8
Son, Young-Ok; Pratheeshkumar, Poyil; Roy, Ram Vinod et al. (2015) Antioncogenic and Oncogenic Properties of Nrf2 in Arsenic-induced Carcinogenesis. J Biol Chem 290:27090-100
Wang, Lei; Hitron, John Andrew; Wise, James T F et al. (2015) Ethanol enhances arsenic-induced cyclooxygenase-2 expression via both NFAT and NF-?B signalings in colorectal cancer cells. Toxicol Appl Pharmacol 288:232-9

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