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) 是美国的一个主要健康问题，每年诊断出超过 200 万例新病例，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。与所有实体瘤一样，NMSC 促进新血管生长（血管生成）以生长和转移。 Thrombospondin-1 (TSP-1) 是第一个被鉴定的血管生成蛋白抑制剂 (2)，在 UVB 照射后以及整个皮肤癌发生的不同步骤中，其表达在表皮中显着下调 (3-6)。芹菜素 (Api, 4', 5, 7- 三羟基黄酮) 是一种存在于水果和蔬菜中的非诱变类黄酮，可抑制由紫外线照射和化学致癌物诱导的 NMSC (7,8)。我们和其他人已经证明，Api 在多种细胞类型中诱导许多抗肿瘤发生和化学预防作用 (9-14)，然而，TSP-1 在 Api 化学预防中的作用从未有过报道。我们的初步结果表明，Api 可阻断 UVB 在体内培养的角质形成细胞和皮肤中对 TSP-1 的下调。我们发现，经 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，HuR 最近被证明在 TSP-1 mRNA 的翻译中发挥重要作用。此外，我们还发现 Api 促进 HuR (15) 从核到细胞质的易位，在此发生 TSP-1 的多核糖体翻译。此外，我们还发现，HuR 表达的 siRNA 敲低会消除 Api 在 UVB 照射的角质形成细胞中恢复正常 TSP-1 水平的能力。我们在 UVB 诱导皮肤癌的体内模型中取得了令人信服的初步结果，证实了 UVB 抑制了表皮中 TSP-1 蛋白的表达，而 Api 恢复了 TSP-1 表达。此外，Api 还能抑制 UVB 诱导的真皮浅层基质炎症和微血管密度 (MVD) 的上调。鉴于 TSP-1 众所周知的抗血管生成作用和较少研究的抗炎作用，Api 诱导 TSP-1 表达很可能是 MVD 减少和炎症浸润的原因。基于这些发现，我们建议测试 Api 通过上调 TSP-1 翻译来恢复 UVB 照射表皮中 TSP-1 表达的新假设。我们进一步假设 Api 对 TSP-1 表达的诱导导致基质室中炎症和血管生成的抑制，并对 NMSC 进行全面化学预防。我们建议使用暴露于 UVB 和/或 Api 的野生型和 Thrombospondin-1-null (TSP-1 -/-) 小鼠和角质形成细胞在基于细胞和体内的研究中检验这一假设。确定 TSP-1 作为芹菜素的关键靶点并证明其在 Api 化学预防中的重要作用将为改进 NMSC 的治疗和预防策略提供新的靶点和原理。