Dioxin and Keratinocyte Differentiation

名称(申请人提供)：2，3，7，8，四氯二苯并对二恶英 TCDD是一种普遍存在的促进肿瘤的环境污染物 形成和调节细胞分化，通过被认为涉及 芳香烃受体(AHR)信号通路。鉴于这项研究 角质形成细胞分化已被证明为研究 肿瘤促进剂发挥作用的机制(S)及该模型 适用于许多分子技术，我们已经启动了对 差异化以实现我们理解TCDD作用的长期目标 在致癌方面。使用正常的人类角质形成细胞(NHK)，我们已经证明 TCDD对NHK细胞的最终抑制作用 分化，这种影响伴随着降低的水平 肿瘤抑制蛋白，p27Kipl，使用ARR拮抗剂的额外研究， 3‘-甲氧基-4’-硝基-黄酮类AHR在介导TCDD中的作用 抑制分化。最后，很明显，TCDD抑制了 通过减少分化细胞的数量进行分化，同时 增加未分化细胞的数量。这些结果和其他结果， 形成了我们总体假设的基础，即TCDD抑制的能力 分化是通过降低肿瘤的表达水平来调节的。 抑制蛋白p27Kipl从而抑制p27Kipl的分化 信号。为了验证这一假设，我们将使用流式细胞术、蛋白质印迹 分析、实时聚合酶链式反应和腺病毒介导的过表达系统 确定：1)TCDD抑制分化的能力是否需要 抑制p27Kipl的表达，2)TCDD对p27Kipl蛋白的调节 在转录或转录后水平，3)TCDD的能力 抑制p27Kipl的表达和分化需要AHR和 Arnt蛋白，4)TCDD抑制分化导致增加) 增殖；5)TCDD的分化作用发生在 基因组水平。

DESCRIPTION (provided by applicant): 2,3,7,8,Tetrachlorodibenzo-p-dioxin \(TCDD\) is a ubiquitous environmental contaminant that promotes tumor formation and modulates cellular differentiation via actions thought to involve the aryl hydrocarbon receptor (AHR) signaling pathway. Given that study of keratinocyte differentiation has been shown to lend important insights into the mechanism(s) by which tumor promoters exert their effects and that this model is amenable to a number of molecular techniques, we have initiated studies of differentiation to fulfill our long-term goal of understanding the role of TCDD in carcinogenesis. Using normal human keratinocytes (NHK), we have shown that administration of TCDD to NHK cells ultimately results in suppression of differentiation and that this effect is accompanied by decreased levels of the tumor suppressor protein, p27Kipl Additional studies using the ARR antagonist, 3'-methoxy-4'nitroflavone implied a role of the AHR in mediating TCDD's suppression of differentiation. Finally, it is apparent that TCDD suppresses differentiation by decreasing the number of differentiating cells while increasing the number of non-differentiating cells. These results and others, form the basis of our overall hypothesis that the ability of TCDD to suppress differentiation is mediated by a decrease in the expression levels of the tumor suppressor protein, p27Kipl thereby diminishing the p27Kipl differentiation signal. To test this hypothesis, we will use flow cytometry, western blot analysis, real time PCR and adenovirus-mediated over expression systems to determine whether: 1) the ability of TCDD to suppress differentiation requires suppression of the expression of p27Kipl, 2) TCDD regulates the p27Kipl protein at the transcriptional or post-transcriptional levels, 3) the ability of TCDD to suppress the expression of p27Kipl and differentiation requires the AHR and ARNT proteins, 4) suppression of differentiation by TCDD results in increased) proliferation, and 5) and the actions of TCDD on differentiation occur at the) genomic level.