Apigenin restores TSP-1 expression in UVB-irradiated keratinocytes

芹菜素恢复 UVB 照射的角质形成细胞中 TSP-1 的表达

• 批准号: 8633023
• 负责人: OLGA Valery VOLPERT
• 金额: $ 43.79万
• 依托单位: NORTHWESTERN UNIVERSITY AT CHICAGO
• 依托单位国家: 美国
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-03-06 至 2018-02-28
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8633023
• 关键词: Affect; Angiogenesis Inhibitors; Angiogenesis Inhibitory Protein; Anti-Inflammatory Agents; Anti-inflammatory; Antigens; Apigenin; Blood Vessels; Carcinogens; Cells; Chemoprevention; Chemopreventive Agent; Country; Cutaneous; Data; Dermis; Development; Diagnosis; Down-Regulation; Endothelial Cells; Epidermis; Exposure to; Extravasation; Flavonoids; Gold; Growth; Health; Human; Immune; In Vitro; Inflammation; Inflammatory Infiltrate; Knockout Mice; Laboratories; Link; Malignant Neoplasms; Mediating; Mediator of activation protein; Messenger RNA; Molecular; Mus; Neoplasm Metastasis; Nuclear; Peptides; Plants; Play; Prevention strategy; Protein Binding; Protein Biosynthesis; Proteins; RNA-Binding Proteins; Regimen; Regulation; Reporting; Role; Skin; Skin Cancer; Skin Carcinogenesis; Skin Carcinoma; Small Interfering RNA; Solid Neoplasm; Testing; Thrombospondin 1; Translations; Tumor Angiogenesis; UV induced; Ultraviolet B Radiation; Ultraviolet Rays; United States; Untranslated Regions; Up-Regulation; angiogenesis; base; carcinogenesis; cell type; chemical carcinogen; cytokine; density; fruits and vegetables; improved; in vivo; in vivo Model; irradiation; keratinocyte; knock-down; mimetics; nanoparticle; new growth; novel; novel strategies; prevent; protein expression; public health relevance; response; skin cancer prevention; tool; treatment strategy; ultraviolet

DESCRIPTION (provided by applicant): Non-melanoma skin cancer (NMSC) is a major health problem in the United States, with over two million new cases diagnosed yearly, making it the most common cancer in this country (1). Ultraviolet B (UVB) radiation is the major carcinogen for non-melanoma skin cancer. Like all solid tumors, NMSC promotes growth of new blood vessels (angiogenesis) in order to grow and metastasize. Thrombospondin-1 (TSP-1) is the first protein inhibitor of angiogenesis to be identified (2), and its expression is markedly downregulated in epidermis following UVB irradiation and throughout distinct steps of skin carcinogenesis (3-6). Apigenin (Api, 4', 5, 7- trihydroxyflavone), a nonmutagenic flavonoid found in fruits and vegetables, inhibits NMSC induced by UV exposure and chemical carcinogens (7,8). We and others have shown that Api induces many antitumorigenic and chemopreventive actions in multiple cell types (9-14), however, the role of TSP-1 in chemoprevention by Api has never been reported. Our preliminary results show that Api blocks downregulation of TSP-1 by UVB in cultured keratinocytes and skin in vivo. We show that regulation of TSP-1 expression in UVB/Api-treated keratinocytes occurs post-transcriptionally and is mediated by RNA-binding protein HuR. Importantly, HuR has recently been demonstrated to play an important role in translation of TSP-1 mRNA. In addition we have shown that Api promotes nuclear to cytoplasmic translocation of HuR (15), where polyribosomal translation of TSP-1 occurs. Furthermore, we have shown that siRNA knockdown of HuR expression abrogates the ability of Api to restore normal TSP-1 levels in UVB-irradiated keratinocytes. Our compelling preliminary results in an established in vivo model of UVB-induced skin carcinogenesis, confirms in vivo that UVB inhibited TSP-1 protein expression in epidermis and Api restored TSP-1 expression. Furthermore, Api inhibited UVB-induced up-regulation of stromal inflammation and microvascular density (MVD) in superficial dermis. Given the well-known anti-angiogenic and less studied anti-inflammatory action of TSP-1, it is likely that induction of TSP-1 expression by Api is the cause of decreased MVD and inflammatory infiltrates. Based on these findings, we propose to test the novel hypothesis that Api restores TSP-1 expression in UVB-irradiated epidermis via upregulation of TSP-1 translation. We further hypothesize that this induction of TSP-1 expression by Api leads to inhibition of inflammation and angiogenesis in the stromal compartment, with overall chemoprevention of NMSC. We propose to test this hypothesis in cell-based and in vivo studies using wild- type and Thrombospondin-1-null (TSP-1 -/-) mice and keratinocytes exposed to UVB and/or Api. Identifying TSP-1 as a key target of apigenin and demonstrating its important role in chemoprevention by Api will provide a new target and rationale for improved treatment and prevention strategies for NMSC.

描述（由申请人提供）：非黑色素瘤皮肤癌（NMSC）是美国的主要健康问题，每年被诊断出200万个新病例，使其成为该国最常见的癌症（1）。紫外线B（UVB）辐射是非黑色素瘤皮肤癌的主要致癌物。像所有实体瘤一样，NMSC促进了新血管的生长（血管生成），以生长和转移。血小板传播1（TSP-1）是要鉴定的血管生成的第一种蛋白抑制剂（2），在UVB辐照后，在表皮和整个皮肤癌变的不同步骤中，其表达在表皮中明显下调（3-6）。阿替锡蛋白（API，4'，5，7-三羟基氟法酮），一种在水果和蔬菜中发现的非植物类黄酮，抑制了紫外线暴露和化学癌引起的NMSC（7,8）。我们和其他人表明，API在多种细胞类型中诱导许多抗肿瘤和化学预防作用（9-14），但是，TSP-1在API中的作用从未报道过。我们的初步结果表明，API在体内培养的角质形成细胞和皮肤中阻断UVB对TSP-1的下调。我们表明，UVB/API处理的角质形成细胞中TSP-1表达的调节发生在转录后，并由RNA结合蛋白HUR介导。重要的是，最近已证明HUR在TSP-1 mRNA的翻译中起着重要作用。此外，我们已经表明，API促进了HUR的核转运（15），其中发生了TSP-1的多核糖体翻译。此外，我们已经表明，HUR表达的siRNA敲低消除了API恢复UVB辐射的角质形成细胞中正常TSP-1水平的能力。我们引人注目的初步结果是在UVB诱导的皮肤致癌作用的体内模型中确定的，在体内证实，UVB抑制了表皮中的TSP-1蛋白表达，而API恢复了TSP-1的表达。此外，API抑制了UVB诱导的浅表真皮中基质炎症和微血管密度（MVD）的上调。鉴于TSP-1的众所周知的抗血管生成和较少研究的抗炎作用，API诱导TSP-1表达可能是MVD降低和炎症性浸润的原因。基于这些发现，我们建议测试新的假设，即API通过上调TSP-1翻译来恢复UVB辐射表皮中TSP-1的表达。我们进一步假设，通过API对TSP-1表达的诱导会导致基质室中炎症和血管生成的抑制，而NMSC的总体化学预防。我们建议使用暴露于UVB和/或API的野生型和血小板蛋白-1-NULL（TSP-1 - / - ）小鼠和角质形成细胞在基于细胞和体内研究中检验这一假设。将TSP-1识别为猿猴的关键靶标，并证明其在API中的化学预防中的重要作用将为改善NMSC的治疗和预防策略提供新的目标和基本原理。