REGULATION OF CYP1A1 IN HUMAN EPITHELIAL CELLS

申请人摘要：本提案的重点是审查 细胞色素P450家族成员CYP 1A 1的组织特异性调节， 正常人的皮肤 CYP 1A 1是一种多环卤代芳香族化合物， 烃诱导单加氧酶。 因为超过一半的癌症 产生于与环境直接接触的上皮细胞， 了解CYP 1A 1的内源性调节和表达， 组织很重要。 关于CYP 1A 1在正常人中的组织特异性调节知之甚少。 人复层鳞状上皮 然而，多环芳烃和多环芳烃依赖 CYP 1A 1的调节是由一个基本的螺旋-环-螺旋转录介导的 含有芳烃受体（AhR）的因子复合物及其 二聚化伴侣，AhR核转运蛋白（Arnt）。 的作用 AhR和Arnt在皮肤组织特异性CYP 1A 1调节中发挥作用， 很好理解。 此外，不知道是否承诺 分化对于皮肤中的CYP 1A 1表达是必要的，或者如果 任何，CYP 1A 1，AhR和Arnt在终末分化程序中发挥作用， 角质形成细胞，复层鳞状上皮的主要细胞类型。 我们 最近发现CYP 1A 1基因的表达和酶活性 是由细胞信号传导事件引起的， 在不存在外源性物质或其它物质的情况下培养的人角质形成细胞 诱导分化的条件，如高水平的钙和 血清的 我们怀疑类似的细胞信号事件有助于 体内复层鳞状上皮细胞中CYP 1A 1诱导。 这本小说 CYP 1A 1诱导机制的研究有助于我们更好地理解哺乳动物细胞的CYP 1A 1诱导机制。 细胞色素P450基因在复层鳞状上皮中的调控 可能有助于鉴定内源性诱导剂和底物 CYP1A1 我们迄今取得的成果使我们 假设细胞粘附的变化是CYP 1A 1的重要调节因子 在正常人复层上皮中。 具体目标是：1） 表征CYP 1A 1在人角质形成细胞中的内源性表达， 在AhR+/+和AhR-/-小鼠角质形成细胞中， 体外和原位分化，2)调查分子 细胞-细胞丢失后角质形成细胞中CYP 1A 1诱导的机制 和细胞-基质接触，以及3）鉴定特定的细胞-细胞或 细胞-基质相互作用，当被破坏时， 角质形成细胞CYP 1A 1，并研究AhR/Arnt信号转导在角质形成细胞CYP 1A 1中的作用。 使用AhR-/-小鼠角质形成细胞的粘附介导的CYP 1A 1诱导。

APPLICANT'S ABSTRACT: The focus of this proposal is to examine the tissue-specific regulation of a cytochrome P450 family member, CYP1A1, in normal human skin. CYP1A1 is a polycyclic and halogenated aromatic hydrocarbon-inducible monooxygenase. Since more than half of all cancers arise in epithelia having direct contact with the environment, an understanding of the endogenous regulation and expression of CYP1A1 in these tissues is important. Little is known about the tissue-specific regulation of CYPlA1 in normal human stratified squamous epithelia. However, PAHs and HAHs-dependent regulation of CYP1A1 is mediated by a basic helix-loop-helix transcription factor complex containing the aryl hydrocarbon receptor (AhR) and its dimerization partner, AhR nuclear translocator protein (Arnt). The role that AhR and Arnt play in tissue-specific CYP1A1 regulation in skin in not well understood. Furthermore, it is unknown if commitment to differentiation is necessary for CYP1A1 expression in skin or what role, if any, CYP1A1, AhR, and Arnt play in the terminal differentiation program of keratinocytes, the major cell type of stratified squamous epithelia. We have recently found that expression of the CYPlAl gene and enzyme activity is rapidly induced by cellular signaling events initiated by suspension of cultured human keratinocytes in the absence of xenobiotics or other differentiation-inducing conditions, such as high levels of calcium and serum. We suspect that similar cellular signaling events contribute to the induction of CYP1A1 in stratified squamous epithelia in vivo. This novel mechanism of CYP1A1 induction should enhance our understanding of mammalian cytochrome P450 gene regulation in stratified squamous epithelia and potentially aid in the identification of endogenous inducers and substrates for CYP1A1. The results we have generated thus far have led us to hypothesize that changes in cell adhesion are important regulators of CYP1A1 in normal human stratified epithelia. The specific aims are: 1) Characterize the endogenous expression of CYP1A1 in human keratinocytes, and in AhR+/+ and AhR-/- mouse keratinocytes at different stages of differentiation in vitro and in situ., 2) Investigate the molecular mechanism of CYP1A1 induction in keratinocytes following loss of cell-cell and cell-substratum contact, and 3) Identify specific cell-cell or cell-substratum interaction that, when disrupted, cause rapid induction of keratinocyte CYP1A1 and investigate the role of the AhR/Arnt signaling in adhesion-mediated CYP1A1 induction using AhR-/- mouse keratinocytes.