Dioxin and Keratinocyte Differentiation

性状（申请人提供）：2，3，7，8，四氯二苯并对二恶英 TCDD是一种普遍存在的环境污染物， 形成和调节细胞分化的行动，认为涉及 芳香烃受体（AHR）信号通路。鉴于这项研究 角质形成细胞的分化已经显示出提供了重要的见解， 肿瘤促进剂发挥其作用的机制，并且该模型 可以通过一些分子技术进行检测，我们已经开始研究 差异化，以实现我们理解TCDD作用的长期目标 在致癌作用中。使用正常人角质形成细胞（NHK），我们已经表明， 对NHK细胞施用TCDD最终导致抑制 分化，这种影响伴随着降低水平的 肿瘤抑制蛋白，p27 Kip 1使用ARR拮抗剂的另外的研究， 3 '-甲氧基-4'-硝基黄酮提示AHR在介导TCDD中起作用 抑制分化。最后，很明显，TCDD抑制了 通过减少分化细胞的数量， 增加非分化细胞的数量。这些结果和其他结果， 形成了我们整体假设的基础，即TCDD抑制 分化由肿瘤表达水平的降低介导， 抑制蛋白p27 Kipl，从而减少p27 Kipl分化 信号了为了验证这一假设，我们将使用流式细胞术，蛋白质印迹， 分析、真实的时间PCR和腺病毒介导的过表达系统， 确定是否：1）TCDD抑制分化的能力需要 抑制p27 Kipl的表达，2）TCDD调节p27 Kipl蛋白 在转录或转录后水平，3）TCDD的能力， 为了抑制p27 Kipl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，和5）和TCDD对分化的作用发生在） 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.