Oxidative stress, Cr(VI) carcinogenesis, and prevention

天然化合物介导的诱导型Nrf 2的活化增强细胞抗氧化剂水平， 抑制ROS，其可用作抑制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R 01赠款的初步研究表明， 在转化后，这些细胞表现出组成型Nrf 2活化，其上调其靶蛋白， 包括SOD和Bcl-2，导致细胞存活和肿瘤发生，标志着金属或 Cr（VI）致癌作用。因此，我们的数据表明，Nrf 2可以是预防的一个重要目标， Cr（VI）在两个阶段的致癌作用。母R 01提案调查了自然资源的保护， 化合物抗Cr（VI）诱导的细胞转化、Cr（VI）转化的细胞诱导的肿瘤发生和 Cr（VI）诱导的血管生成和肿瘤形成，总体主题集中在保护终点 抑制Cr（VI）诱导的致癌作用。此ViCTER应用程序扩展了父R 01的范围， 通过与自噬，金属， 致癌作用，以及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的以下主要 调查结果。(a)EGFR在Cr（VI）转化的BEAS-2B细胞和来自人的肺组织中组成性激活。 动物和暴露于Cr（VI）的癌症患者。(b)EGFR激活启动自噬， 自噬缺陷通过阻断自噬体和溶酶体之间的融合，导致p62 在Cr（VI）转化的细胞中的Nrf 2积累和组成性活化。(c)龙谷明，一种天然的 化合物，激活正常细胞中的诱导型Nrf 2，并抑制正常细胞中EGFR和Nrf 2的组成型激活。 Cr（VI）转化细胞。中心假设是piperlongumine激活诱导型Nrf 2，导致 降低ROS水平和抑制正常细胞的恶性转化，并且该化合物 抑制EGFR活化，导致自噬过程的阻断，p62和Nrf 2的组成性活化， 和Cr（VI）转化细胞的肿瘤发生。目的1将检验EGFR激活启动 自噬通过激活TFEB，其上调Beclin 1和p62并产生自噬体。目的2 将检验EGFR下调LAMP 2a的假设，从而抑制 自噬体和溶酶体，导致细胞内p62的积累和组成性Nrf 2活化， 动物和人类的水平。目的3将证明（a）piperlongumine激活诱导型Nrf 2，降低ROS， 并抑制Cr（VI）诱导的正常细胞恶性转化;（B）该天然化合物抑制EGFR 活化、自噬起始和自噬缺陷、p62和Nrf 2的组成性活化，以及 Cr（VI）转化细胞的肿瘤发生;和（c）piperlongumine防止动物中的肿瘤形成 暴露于Cr（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).