Molecular Mechanism of Arsenic Carcinogenesis

描述（由申请人提供）：人体长期暴露于无机砷会诱发肺癌和其他癌症。砷致癌的分子机制仍有待阐明。我们的初步研究表明，砷增加活性氧（ROS）的产生，抑制miR-199和miR-148的表达，并增加ERBB 2，PKM 2，NF-kB，HIF-1和IL-8在肺上皮细胞中的表达。砷治疗还诱导细胞转化、肿瘤生长和血管生成。我们假设砷通过诱导NOX 2、p47 phox、ROS和DNMT 1表达抑制miR-199/148表达; miR-199/148下调通过ERBB 2和PKM 2/NF-：B靶点调节癌发生（细胞转化、肿瘤生长和血管生成）。为了验证这一假设，提出了三个目标。目的1探讨砷通过诱导NOX 2/p47 phox/DNMT 1、ROS生成抑制miR-199和miR-148表达，并通过下调miR-199/148进而调节ERBB 2表达和PKM 2/NF-kB相互作用的机制。我们将调查：1）砷是否通过诱导NOX 2、p47 Phox、ROS和DNMT 1抑制miR-199和miR-148表达; 2）砷是否通过下调miR-199/148诱导ERBB 2和PKM 2表达; 3）PKM 2的哪些区域与NF-κ B p65亚基结合以调节IL-8和HIF-1表达。目的2探讨miR-199/148下调在诱导ERBB 2和PKM 2/NF-kB表达中的作用，以调节细胞转化和肿瘤生长。我们将确定：1）砷是否通过ROS和DNMT 1诱导的miR-199/148下调来诱导细胞转化和肿瘤生长; 2）ERBB 2和PKM 2是否是miR-199/148调节砷诱导的转化和肿瘤生长的关键直接靶点; 3）PKM 2/NF-：B相互作用是否起重要作用。目的3通过miR-199/148/ERBB 2/PKM 2/NF-kB轴旁分泌诱导HIF-1和IL- 8表达，探讨砷诱导血管新生的机制。我们还将使用嵌合肿瘤模型确定IL-8的分泌是否会通过内皮细胞中的功能性IL-8受体（旁分泌效应）诱导肿瘤血管生成。这项研究将为理解miRNAs如何通过ERBB 2和PKM 2/NF-kB轴调节砷诱导的肿瘤生长和血管生成提供重要的范式转变。鉴于ERBB 2、PKM 2、NF-kB、HIF-1和IL-8在不同类型癌症中的重要作用，拟议的研究对于未来砷诱导的癌症以及其他人类癌症的基于机制的预防和治疗研究将是重要的。

DESCRIPTION (provided by applicant): Long-term human exposure to inorganic arsenic induces lung and other cancers. The molecular mechanisms of arsenic-induced carcinogenesis remain to be elucidated. Our preliminary studies show that arsenic increases reactive oxygen species (ROS) production, inhibits miR-199 and miR-148 expression, and increases ERBB2, PKM2, NF-kB, HIF-1 and IL-8 expression in lung epithelial cells. Arsenic treatment also induces cell transformation, tumor growth and angiogenesis. We hypothesize that arsenic suppresses miR-199/148 expression through the induction of NOX2, p47phox, ROS; and DNMT1 expression; and miR-199/148 downregulation regulates carcinogenesis (cell transformation, tumor growth, and angiogenesis) through targets: ERBB2 and PKM2/NF-:B. To test this hypothesis, three aims are proposed. Aim 1 will investigate the mechanisms of arsenic in suppressing miR-199 and miR-148 expression through NOX2/p47phox/DNMT1 induction, ROS generation; and miR-199/148 downregulation in turn regulates ERBB2 expression and PKM2/NF-kB interaction. We will investigate: 1) whether arsenic suppresses miR-199 and miR-148 expression through the induction of NOX2, p47Phox, ROS, and DNMT1; 2) whether arsenic induces ERBB2 and PKM2 expression by miR-199/148 downregulation; 3) what regions of PKM2 bind with NF-kB p65 subunit for regulating IL-8 and HIF-1 expression. Aim 2 will investigate the roles of miR-199/148 downregulation in inducing ERBB2 and PKM2/NF-kB expression for regulating cell transformation and tumor growth. We will determine: 1) whether arsenic induces cell transformation and tumor growth through ROS- and DNMT1-induced miR-199/148 downregulation; 2) whether ERBB2 and PKM2 are key direct targets of miR-199/148 for regulating arsenic-induced transformation and tumor growth; and 3) whether PKM2/NF-:B interaction plays an important role. Aim 3 will investigate the mechanisms of arsenic-induced angiogenesis through miR-199/148/ERBB2/PKM2/NF-kB axis for inducing HIF-1 and IL- 8 via paracrine effect using animal models. We will also determine whether secretion of IL-8 will induce tumor angiogenesis through functional IL-8 receptors in endothelial cells (paracrine effect) using chimeric tumor model. This proposed study would provide an important paradigm shift in understanding how miRNAs regulate arsenic-induced tumor growth and angiogenesis through ERBB2 and PKM2/NF-kB axis. Given the important roles of ERBB2, PKM2, NF-kB, HIF-1, and IL-8 in different types of cancers; the proposed studies would be important for future studies on mechanism-based prevention and treatment for arsenic-induced cancer as well as other human cancers.