Oxidative stress, Cr(VI) carcinogenesis, and prevention

氧化应激、Cr(VI) 致癌作用及预防

• 批准号: 9237917
• 负责人: Xianglin Shi
• 金额: $ 41.55万
• 依托单位: UNIVERSITY OF KENTUCKY
• 依托单位国家: 美国
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-05-01 至 2020-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9237917
• 关键词: Animals; Antioxidants; Area; Autophagocytosis; Autophagosome; BCL2 gene; Binding; Cancer Patient; Carcinogenesis Mechanism; Cell Survival; Cells; Data; Data Analyses; Diet; Elements; Ensure; Epidermal Growth Factor Receptor; Epithelial; Exhibits; Experimental Designs; Goals; Grant; Human; Lung; Lung Neoplasms; Lysosomes; Malignant - descriptor; Mediating; Membrane Proteins; Metal Carcinogenesis; Metals; Normal Cell; Oxidative Stress; Parents; Play; Prevention; Process; Promoter Regions; Proteins; Reactive Oxygen Species; Receptor Activation; Role; Structure of parenchyma of lung; Superoxide Dismutase; Testing; Tumor Tissue; activating transcription factor; angiogenesis; animal tissue; base; cancer cell; cancer prevention; carcinogenesis; carcinogenicity; cell transformation; chromium hexavalent ion; interdisciplinary collaboration; novel strategies; nuclear factor-erythroid 2; prevent; response; tumor; tumorigenesis

Natural compound-mediated activation of inducible Nrf2 enhances the cellular antioxidant levels and suppresses ROS, which can be used as a strategy to inhibit Cr(VI)-induced malignant transformation, representing the first stage of Cr(VI) carcinogenesis. Our preliminary studies from the parent R01 grant show that after transformation these cells exhibit constitutive Nrf2 activation, which up-regulates its target proteins, including SOD and Bcl-2, leading to cell survival and tumorigenesis, signifying the second stage of metal or Cr(VI) carcinogenesis. Thus, our data indicate that Nrf2 can be an important target for prevention against Cr(VI) carcinogenesis at both stages. The parent R01 proposal investigates the protection of a natural compound against Cr(VI)-induced cell transformation, Cr(VI)-transformed cells-induced tumorigenesis, and Cr(VI)-induced angiogenesis and tumor formation with overall theme focused on endpoints of the protection aganist Cr(VI)-induced carcinogenesis. This ViCTER application expands the scope of the parent R01 through developing new transdisciplinary collaboration by engaging with experts in the areas of autophagy, metal carcinogenesis, and mechanism-based cancer prevention to focus on mechanistic aspect on Cr(VI)-induced carcinogenesis and its protection using a natural compound. This study is based on our following major findings. (a) EGFR is constitutively activated in Cr(VI)-transformed BEAS-2B cells and in lung tissues from animals and a cancer patient exposed to Cr(VI). (b) EGFR activation initiates autophagy and causes autophagy deficiency by blocking the fusion between autophagosomes and lysosomes, leading to p62 accumulation and constitutive Nrf2 activation in Cr(VI)-transformed cells. (c) Piperlongumine, a natural compound, activates inducible Nrf2 in normal cells and inhibits constitutive activations of EGFR and Nrf2 in Cr(VI)-transformed cells. The central hypothesis is that piperlongumine activates inducible Nrf2, leading to decreased level of ROS and inhibition of malignant transformation of normal cells and that this compound inhibits EGFR activation, resulting in blockages of autophagy process, constitutive activations of p62 and Nrf2, and tumorigenesis of Cr(VI)-transformed cells. Aim 1 will test the hypothesis that EGFR activation initiates autophagy by activating TFEB, which up-regulates Beclin 1 and p62 and generates autophagosomes. Aim 2 will test the hypothesis that EGFR down-regulates LAMP2a, resulting in inhibition of the fusion between autophagosomes and lysosomes, leading to accumulation of p62 and constitutive Nrf2 activation at cellular, animal, and human levels. Aim 3 will demonstrate (a) piperlongumine activates inducible Nrf2, decreases ROS, and inhibits Cr(VI)-induced malignant transformation of normal cells; (b) this natural compound inhibits EGFR activation, autophagy initiation and autophagy deficiency, constitutive activations of p62 and Nrf2, and tumorigenesis of Cr(VI)-transformed cells; and (c) piperlongumine protects from tumor formation in animals exposed to Cr(VI).

天然化合物介导的诱导型 Nrf2 激活可增强细胞抗氧化水平 抑制 ROS，可作为抑制 Cr(VI) 诱导的恶性转化的策略， 代表 Cr(VI) 致癌作用的第一阶段。我们对母公司 R01 资助的初步研究显示 转化后，这些细胞表现出组成型 Nrf2 激活，从而上调其靶蛋白， 包括SOD和Bcl-2，导致细胞存活和肿瘤发生，标志着金属或肿瘤的第二阶段 Cr(VI) 致癌。因此，我们的数据表明 Nrf2 可以成为预防 两个阶段的 Cr(VI) 致癌作用。母版 R01 提案调查了自然环境的保护 抗 Cr(VI) 诱导的细胞转化、Cr(VI) 转化的细胞诱导的肿瘤发生的化合物，以及 Cr(VI) 诱导的血管生成和肿瘤形成，总体主题侧重于保护终点 抗 Cr(VI) 诱导的致癌作用。此 ViCTER 应用程序通过以下方式扩展了父 R01 的范围 通过与自噬、金属等领域的专家合作，发展新的跨学科合作 致癌作用和基于机制的癌症预防重点关注 Cr(VI) 诱导的机制方面 致癌作用及其使用天然化合物的保护。这项研究是基于我们以下专业 发现。 (a) EGFR 在 Cr(VI) 转化的 BEAS-2B 细胞和肺组织中被组成型激活 接触 Cr(VI) 的动物和癌症患者。 (b) EGFR 激活启动自噬并引起 通过阻断自噬体和溶酶体之间的融合来导致自噬缺陷，从而导致 p62 Cr(VI) 转化细胞中 Nrf2 的积累和组成型激活。 (c) Piperlongumine，一种天然的 化合物，激活正常细胞中的诱导型 Nrf2，并抑制 EGFR 和 Nrf2 的组成型激活 Cr(VI) 转化细胞。核心假设是 Piperlongumine 激活诱导型 Nrf2，从而导致 降低ROS水平并抑制正常细胞的恶性转化，并且该化合物 抑制 EGFR 激活，导致自噬过程受阻、p62 和 Nrf2 组成型激活， 和 Cr(VI) 转化细胞的肿瘤发生。目标 1 将检验 EGFR 激活启动的假设 通过激活 TFEB 进行自噬，TFEB 上调 Beclin 1 和 p62 并生成自噬体。目标2 将检验 EGFR 下调 LAMP2a 的假设，从而抑制两者之间的融合 自噬体和溶酶体，导致细胞内 p62 的积累和组成型 Nrf2 激活， 动物和人类水平。目标 3 将证明 (a) Piperlongumine 激活诱导型 Nrf2，降低 ROS， 并抑制 Cr(VI) 诱导的正常细胞恶性转化； (b) 这种天然化合物抑制 EGFR 激活、自噬启动和自噬缺陷、p62 和 Nrf2 的组成型激活，以及 Cr(VI) 转化细胞的肿瘤发生； (c) 胡椒长明可防止动物形成肿瘤 暴露于 Cr(VI)。