Cell survival and arsenic carcinogenesis

细胞存活和砷致癌

• 批准号: 8762450
• 负责人: Xianglin Shi
• 金额: $ 33.41万
• 依托单位: UNIVERSITY OF KENTUCKY
• 依托单位国家: 美国
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-01-15 至 2015-10-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8762450
• 关键词: Antioxidants; Apoptosis; Apoptotic; Arsenic; Arsenites; BCL2 gene; Cancer Model; Cell Death; Cell Survival; Cells; Characteristics; Chronic; DNA Damage; Dose; Enzymes; Epithelial; Epithelial Cells; Exhibits; Exposure to; GADD45; Generations; Growth; Health; Human; Impairment; Kidney; Lipid Peroxidation; Liver; Lung; Malignant neoplasm of lung; Malignant neoplasm of urinary bladder; Microfilaments; Modeling; Molecular; NADPH Oxidase; Pathway interactions; Post-Translational Protein Processing; Premalignant; Prevention strategy; Property; Reactive Oxygen Species; Relative (related person); Resistance; Role; Skin; Testing; Toxic effect; Transcription Factor AP-1; antioxidant enzyme; arsenic-induced carcinogenesis; cancer cell; carcinogenesis; catalase; cell growth; cell motility; cell transformation; genetic regulatory protein; knock-down; migration; novel; overexpression; rapid growth; response; tumor growth; tumorigenesis

DESCRIPTION (provided by applicant): 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.

描述（由申请人提供）：虽然砷诱发致癌的分子机制仍有待研究，但砷产生的活性氧（ROS）被认为是重要的。砷产生的ROS可引起DNA损伤、脂质过氧化和蛋白质修饰，从而导致多种致癌反应。我们的初步研究表明，砷转化的人肺支气管上皮（BEAS-2B）细胞相对于未转化的细胞，砷诱导的ROS产生能力显着降低。 ROS 生成的减少赋予细胞癌前特征，包括快速生长。砷转化细胞在暴露于砷后表现出细胞凋亡减少（细胞凋亡抗性）。该提议假设，由于 ROS 生成能力较低，砷转化细胞会产生凋亡抗性并增加细胞存活率，从而促进砷诱导致癌的整体机制。提出了三个目标来检验这一假设。目标 1 将研究砷转移细胞中 ROS 生成减少的机制。我们将研究 ROS 生成途径的受损是否是砷转化 BEAS-2B 细胞中砷诱导的 ROS 生成水平低的原因。我们还将研究转化细胞中抗氧化酶水平的增加是否会导致 ROS 生成水平的降低。这一目标的完成将建立砷转化细胞中ROS产生减少的机制。目标 2 将研究 ROS 生成减少在砷转化细胞抗凋亡中的作用。我们研究 (a) 砷转化细胞中 ROS 生成的减少是否是砷转化细胞中凋亡抵抗的原因； (b)砷转化细胞是否比其传代匹配的对照细胞具有更高的SOD和过氧化氢酶抗氧化活性； (c) 转化细胞中抗氧化酶的敲低或 NADPH 氧化酶的过度表达是否会增加 ROS 的产生并增强响应砷刺激的细胞凋亡； (d)敲低Bcl-2是否会增加砷转化细胞的凋亡； (e)砷转化细胞是否会由于ROS生成减少和细胞凋亡抵抗而表现出快速生长以及增强的侵袭和迁移。总的来说，这个目标将证明ROS在砷转化细胞的凋亡抵抗中的作用。目标3将研究砷转化细胞诱导肿瘤发生和细胞凋亡的作用。我们将研究凋亡抵抗在砷转化细胞的肿瘤发生中的作用。我们还将使用皮肤肿瘤发生模型和原位肺癌模型研究ROS和凋亡调节蛋白Bcl-2在砷转化细胞诱导的肿瘤发生中的作用。预计通过 Bcl-2 敲低增加砷转化细胞的凋亡将减少肿瘤生长。类似地，细胞ROS产生能力的改变，即通过异位过度表达和ROS清除和产生酶的敲低，将对砷转化细胞的肿瘤发生产生影响。