Endogenous photosensitizers in skin carcinogenesis

描述（由申请人提供）：本申请旨在确定皮肤结构蛋白（角蛋白、胶原蛋白和弹性蛋白）作为内源性紫外线致敏剂在皮肤光损伤中的致病作用，并评估这些新靶点对化学预防光致癌和光老化的调节作用。内源性敏化剂引发的光氧化应激是皮肤光损伤的关键机制，但负责光驱动活性氧（ROS）产生的光动力非dna发色团的分子性质尚不清楚。应用中总结的试点数据支持皮肤细胞外基质蛋白中含有的紫外线发色团是有效的内源性光敏剂的假设。为了验证这一假设，将使用重建的表皮、真皮层和全层人体皮肤组织等效物来定量控制酶和非酶来源的蛋白质uv发色团（目的1）。敏化剂依赖性和独立ROS生成对总和分异太阳紫外线的响应将被确定，结果将通过直接化学分析进行验证（目标2）。已建立的光氧化应激分子和细胞生物标志物将被评估为敏化剂含量和辐射剂量的函数。将研究已知的光致癌和光老化生物标志物的光敏增强（目标3）。光激发态物理猝灭剂作为一种新型的局部化学预防剂用于抑制重建人体皮肤的致敏性光损伤，其治疗潜力将被评估。将对具有可控敏化剂含量的重建人体皮肤进行辐照，并评估原型猝灭剂作为光激发态直接分子拮抗剂的化学预防潜力。一种新型的次级胺药效团，通过物理失活激发态分子和单线态氧而不需要化学耗竭来保护人类皮肤细胞免受光敏，将作为一种原型化学预防剂进行测试，并衍生出最佳的局部递送（目的4）。铅猝灭剂光激发态的有效性将在光致癌动物模型中进行测试。本研究将验证内源性皮肤结构成分作为化学预防皮肤光致癌和光老化的新分子靶点，并开发出一类新的光保护剂。

DESCRIPTION (provided by applicant): This application aims to establish a causative role of skin structural proteins (keratin, collagen, and elastin) as endogenous UV-sensitizers in skin photodamage and evaluates modulation of these novel targets for chemoprevention of photocarcinogenesis and photoaging. Photooxidative stress initiated by solar irradiation of endogenous sensitizers is a key mechanism of skin photodamage, but the molecular nature of the photodynamic non-DNA chromophores responsible for light-driven production of reactive oxygen species (ROS) is unknown. Pilot data summarized in the application support the hypothesis that UV chromophores contained exclusively in extracellular matrix proteins of skin are potent endogenous photosensitizers. To test this hypothesis reconstructed epidermis, dermis, and full thickness human skin tissue equivalents will be used to allow quantitative control of protein UV-chromophores of both enzymatic and non-enzymatic origin (aim 1). Sensitizer-dependent and independent ROS production in response to total and fractionated solar UV light will be determined and results will be validated by direct chemical analyses (aim 2). Established molecular and cellular biomarkers of photooxidative stress will be assessed as a function of sensitizer content and radiation dose. Photosensitized enhancement of known biomarkers of photocarcinogenesis and photoaging will be studied (aim 3). The therapeutic potential of physical quenchers of photoexcited states as a novel class of topical chemopreventive agents for suppression of sensitized photodamage in reconstructed human skin will be evaluated. Reconstructed human skin with controlled sensitizer content will be irradiated and the chemopreventive potential of prototype quenchers as direct molecular antagonists of photoexcited states will be evaluated. A novel secondary amine pharmacophore, which protects human skin cells against photosensitization by physical deactivation of excited state molecules and singlet oxygen without chemical depletion, will be tested as a prototype chemopreventive agent and derivatized for optimal topical delivery (aim 4). The efficacy of the lead quencher of photoexcited states will be tested in an animal model of photocarcinogenesis. This study will validate endogenous structural skin components as novel molecular targets for chemoprevention in skin photocarcinogenesis and photoaging and lead to a new class of photoprotective agents.