Role of AhR/Arnt Signaling Pathway in Carcinogenesis

描述(申请人提供)：恶性黑色素瘤在工业化国家呈上升趋势。事实上，从1973年到1992年，与黑色素瘤相关的死亡率在美国增加了34%。然而，几乎没有开发出有效的黑色素瘤治疗方法。我们认为芳香烃受体(AhR)途径通过激活基质重塑酶在黑色素瘤的进展中起作用。我们选择了2，3，7，8-四氯二苯并对二恶英(TCDD)作为激活AhR途径的试剂。TCDD及其相关的多环和卤代芳烃(PAH/HAH)是普遍存在的环境污染物，是工业燃烧的无意副产物。TCDD是检测黑色素瘤AhR通路的理想方法，原因有三：(1)皮肤是TCDD激活AhR途径的靶组织；TCDD不是代谢的；(3)TCDD是非诱变的，因此我们观察到的效应应该与AhR途径的激活直接相关。我们假设，TCDD激活AhR/Arnt通路通过改变参与基质重塑的基因，特别是基质金属蛋白酶(MMPs)的表达来刺激黑色素瘤的进展。基质金属蛋白酶活性是细胞通过基质屏障进行迁移所必需的，这些酶的表达与侵袭性和侵袭性肿瘤相关。我们在黑色素瘤细胞中的初步数据表明，非侵袭性和侵袭性黑色素瘤细胞对TCDD都有反应，侵袭性黑色素瘤细胞对TCDD暴露有MMPs的反应。此外，我们还显示，当用TCDD治疗时，黑色素瘤细胞的侵袭力增加。这表明TCDD通过激活基质降解直接增加黑色素瘤的侵袭性。因此，这项建议的具体目标是：(1)阐明TCDD诱导黑色素瘤细胞MMPs表达的分子机制。(2)阐明AhR在TCDD诱导的黑色素瘤基质金属蛋白酶表达变化中的作用。(3)通过体外侵袭实验证明AhR通路在黑色素瘤迁移和侵袭中的作用。(4)利用三维皮肤模型系统，确定细胞间相互作用对AhR激活基质金属蛋白酶表达的影响。

DESCRIPTION (provided by applicant): Malignant melanoma is on the rise in industrialized nations. Indeed, the incidence of mortality related to melanoma has increased by 34% in the United States from 1973-1992. However, there are few effective treatments developed for melanoma. We propose that the aryl hydrocarbon receptor (AhR) pathway plays a role in melanoma progression through the activation of matrix remodeling enzymes. We have chosen to use 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) as the agent to activate the AhR- pathway. TCDD and related polycyclic and halogenated aromatic hydrocarbons (PAH/HAH) are ubiquitous environmental contaminants that are the unintentional by-products of industrial combustion. TCDD is ideal for examination of the AhR pathway in melanoma for three reasons: (1.) skin is a target tissue for TCDD-activation of the AhR pathway; (2.) and TCDD is not metabolized; and (3) TCDD is non-mutagenic, and therefore the effects we observe should be directly related to activation of the AhR pathway. We hypothesize that TCDD-activation of the AhR/Arnt pathway stimulates melanoma progression by altering expression of the genes involved in matrix remodeling, specifically the matrix metalloproteinases (MMPs). MMP activity is necessary for cell migration through matrix barriers, and expression of these enzymes correlates with aggressive and invasive tumors. Our preliminary data in melanoma cells demonstrate that both non-invasive and invasive melanoma lines are responsive to TCDD, and invasive melanoma cells express MMPs in response to TCDD exposure. Further, we also show increased invasiveness of melanoma cells when treated with TCDD. This suggests that TCDD directly increases melanoma invasion by activating matrix degradation. Therefore, the specific aims for this proposal are: (1.) Elucidate the molecular mechanism mediating TCDD-induced expression of MMPs in melanoma cell lines. (2.) Elucidate the role of the AhR in TCDD-induced changes in MMP expression in melanoma. (3.) Demonstrate the role of the AhR pathway in melanoma migration and invasion using an in vitro invasion assay. (4.) Using a three-dimensional skin model system, determine the role of cell-cell interaction on AhR-activation of MMP expression.