Endogenous photosensitizers in skin carcinogenesis

描述(申请人提供)：本申请旨在确定皮肤结构蛋白(角蛋白、胶原和弹性蛋白)作为内源性紫外线敏感剂在皮肤光损伤中的致病作用，并评估这些新靶点在化学预防光癌和光老化方面的调节作用。由内源性光敏剂引发的光氧化应激是皮肤光损伤的关键机制，但光动力非DNA生色团负责光驱动产生活性氧物种(ROS)的分子性质尚不清楚。在申请中总结的试点数据支持这样的假设，即皮肤细胞外基质蛋白中仅包含的UV生色团是有效的内源性光敏剂。为了验证这一假设，将使用重建的表皮、真皮和全层人类皮肤组织等价物来定量控制酶来源和非酶来源的蛋白质UV-发色团(目标1)。将确定对总的和分次的太阳紫外光的依赖敏感剂和独立产生的ROS，并将通过直接化学分析验证结果(目标2)。已建立的光氧化应激的分子和细胞生物标记物将作为敏化剂含量和辐射剂量的函数进行评估。将研究光致癌和光老化的已知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类新型的局部化学预防药物，用于抑制人体重建皮肤的致敏性光损伤，其治疗潜力将被评估。具有受控敏化剂含量的重建的人体皮肤将被照射，并将评估原型猝灭剂作为光激发态的直接分子拮抗剂的化学预防潜力。一种新的次级胺药效团，通过激发态分子和单线态氧的物理失活保护人类皮肤细胞免受光敏作用的影响，而不会耗尽化学物质，将作为化学预防药物的原型进行测试和衍生化，以实现最佳的局部给药(目标4)。光激发态铅猝灭剂的有效性将在光致癌的动物模型中进行测试。这项研究将验证内源性皮肤结构成分作为化学预防皮肤光癌和光老化的新分子靶点，并导致一类新的光保护剂。

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.