Oxidative stress, Cr(VI) carcinogenesis, and prevention

天然化合物介导的诱导型NRF2激活可提高细胞抗氧化水平和 抑制ROS，这可以作为一种策略来抑制铬(VI)诱导的恶性转化， 代表了铬(VI)致癌的第一阶段。我们对父母R01赠款的初步研究表明 这些细胞在转化后表现出结构性的Nrf2激活，上调其靶蛋白， 包括SOD和Bcl-2，导致细胞存活和肿瘤发生，标志着金属或金属的第二阶段 六价铬致癌。因此，我们的数据表明，NRF2可以成为预防疟疾的重要靶点 铬(VI)在两个阶段的致癌作用。家长R01提案调查了对自然资源的保护 抗铬(VI)诱导的细胞转化、铬(VI)转化的细胞诱导的肿瘤形成的化合物，以及 铬(VI)诱导的血管生成和肿瘤形成，总体主题集中在保护的终点 抗铬(VI)致癌作用。此Victer应用程序通过以下方式扩展父R01的范围 通过与自噬、金属等领域的专家开展新的跨学科合作 铬(VI)致癌机理及防癌机理研究 使用一种天然化合物的致癌和保护作用。这项研究基于我们的以下主要研究 调查结果。(A)EGFR在铬(VI)转化的BEAS-2B细胞和肺组织中被结构性激活 动物和一名癌症患者暴露于铬(VI)。(B)EGFR激活启动自噬并导致 通过阻止自噬小体和溶酶体之间的融合而导致的自噬缺陷，导致p62 铬(VI)转化细胞中Nrf2的积聚和结构性激活。(C)天然胡萝卜素 化合物，激活正常细胞中可诱导的Nrf2，并抑制EGFR和Nrf2的结构性激活 铬(VI)转化细胞。中心假设是，胡椒碱激活了可诱导的Nrf2，导致 降低ROS水平，抑制正常细胞恶性转化，该化合物 抑制EGFR的激活，导致自噬过程的阻断，p62和Nrf2的结构性激活， 和铬(VI)转化细胞的成瘤。目标1将检验EGFR激活启动的假设 通过激活TFEB实现自噬，TFEB上调Beclin 1和p62并产生自噬小体。目标2 将检验这样的假设，即EGFR下调LAMP2A，导致抑制 自噬小体和溶酶体，导致p62的积累和细胞内结构性的Nrf2激活， 动物和人类的水平。目标3将证明：(A)胡椒碱激活诱导性NRF2，降低ROS， 并抑制铬(VI)诱导的正常细胞的恶性转化；(B)该天然化合物抑制EGFR 激活、自噬启动和自噬缺陷、p62和Nrf2的结构性激活，以及 铬(VI)转化细胞的肿瘤发生；以及(C)胡椒胺对动物肿瘤形成的保护作用 暴露于铬(VI)。

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).