Cell Survival Advantage in Cadmium Induced Carcinogenesis

项目摘要 暴露于镉（Cd）与包括前列腺癌在内的一系列人类发病机制有关 （CaP）。镉暴露与前列腺血清抗原（PSA）异常之间存在明显的剂量-反应关系， 在接触镉的男性中发现了钙磷标志物。然而，这种现象背后的分子机制 镉暴露后的恶性细胞转化尚待确定，而镉与细胞增殖之间的关系尚待确定。 和CaP在临床前和临床模型中的作用已经很好地建立。此应用程序的目标是 研究镉如何引起恶性细胞转化（从正常到 转化的细胞）和通过Cd转化的细胞（转化的细胞）的肿瘤发生的发展 细胞致肿瘤）。我们的初步结果表明，在细胞转化过程中，镉暴露 诱导内质网（ER）应激，这触发了应激转导物的磷酸化，包括 PERK和eIF 2-α导致ATF 4的激活，并启动自噬的诱导，从而保护Cd-2。 受损细胞虽然，观察到自噬标记物（Atg-12和Atg-16 L，LC 3B和Lamp 1）的诱导， 在镉处理的细胞中，由于自噬体和自溶酶体的失败，自噬过程是不完整的 融合，这使得受损细胞能够增殖转化。p62在镉中的大量积累- 处理的细胞，这也证实了有缺陷的自噬。通过siRNA沉默EGFR激活或 药理学抑制剂显着抑制转化细胞的生长，但在镉处理的正常 细胞或镉转化细胞，表明EGFR激活起着关键作用，只有在细胞 转型由Cd转化细胞产生的异种移植肿瘤组织表达高水平的ATF-4， EGFR、p62和LC 3B与体外结果相关。此外，增加的蛋白质（ATF- 4、EGFR、p62和LC 3B）在人CaP标本中的表达与Gleason sum的一致性，与良性CaP标本相比， 前列腺增生和“正常”邻近组织。根据研究结果，我们假设慢性暴露 前列腺上皮细胞的镉引起ER应激，随后有缺陷的自噬，导致增加 导致恶性细胞转化和转化细胞EGFR活化的受损细胞的存活 在肿瘤发生中起重要作用。提出了三个具体目标：目标-1：证明镉导致 ER-应激，这反过来又诱导前列腺上皮细胞转化过程中有缺陷的自噬。 目的2：研究缺陷性自噬的保护作用，其增加镉损伤细胞的存活 在前列腺上皮细胞的转化过程中。目的-3：研究镉诱导的小鼠肿瘤发生 并验证人类前列腺标本中的分子标记。

Project Summary Exposure to cadmium (Cd) is associated with a spectrum of human pathogenesis including the prostate cancer (CaP). A clear dose-response relation between Cd-exposure and abnormal prostate serum antigen (PSA), a marker for CaP have been reported in men exposed to Cd. However, the molecular mechanism underlying the malignant cell transformation following Cd exposure is yet to be determined, while the association between Cd and CaP in both pre-clinical and clinical models are well established. The goal of this application is to investigate the underlying mechanism of how Cd causes malignant cell transformation (from normal to transformed cells) and on the development of tumorigenesis by the Cd-transformed cells (transformed cells to tumorigenesis). Our preliminary results suggest that during cellular transformation, Cd exposure induced endoplasmic reticulum (ER)-stress, which triggered the phosphorylation of stress transducers including PERK and eIF2-α resulted in the activation of ATF4 and initiate the induction of autophagy that protects Cd- damaged cells. Although, induction of autophagy markers (Atg -12 and Atg-16L, LC3B and Lamp1) were seen in Cd-treated cells, the autophagy process is incomplete, due to failure autophagosome and autolysosome fusion, which allowed the damaged cell to proliferate for transformation. A massive accumulation of p62 in Cd- treated cells, which also confirmed the defective autophagy. Silencing EGFR activation by siRNA or pharmacological inhibitors significantly inhibited the growth in transformed cells, but not in Cd-treated normal cells or Cd- transforming cells suggesting that EGFR activation plays a critical role, only after cellular transformation. Xenograft tumor tissues generated by Cd-transformed cells expressed high levels of ATF-4, EGFR, p62 and LC3B in correlation with in vitro findings. Moreover, increased expression of the proteins (ATF- 4, EGFR, p62, and LC3B) in human CaP specimen’s agreement with Gleason sum in comparison with benign prostatic hyperplasia and “normal” adjacent tissues. Based on the results we hypothesize that Chronic exposure of prostate epithelial cells to Cd causes ER-stress and subsequently defective autophagy, leading to increased survival of damaged cells that result in malignant cell transformation and in transformed cell EGFR activation play a significant role in tumorigenesis. Three specific aims are proposed: Aim-1: To demonstrate that Cd causes ER-stress which in turn induced defective autophagy during the transformation of prostate epithelial cells. Aim 2: Investigate the protective role of defective autophagy, which increases the survival of Cd-damaged cells during the transformation of prostate epithelial cells. Aim-3: study Cd-induced tumorigenesis in mouse models and validate the molecular markers in human prostate specimens.