Targeting multiple skin cancer pathways using citrus auraptene and ATRA

描述(申请人提供)：非黑色素瘤皮肤癌(NMSC)越来越需要安全、长期的预防性治疗，这是对高危群体的特别威胁，例如不断增长的免疫功能受损的实体器官移植患者、艾滋病毒患者和老年非西班牙裔高加索人。我们已经证明，具有良好特征的化学预防维生素A代谢物全反式维甲酸(ATRA)与生物活性膳食剂Aur(Aur)相结合，可以协同或超相加地抑制小鼠异种移植模型中皮肤鳞状细胞癌(SCC)肿瘤的生长。我们研究的一个长期目标是开发有效的上皮癌化学预防治疗方法。为了与这一目标保持一致，本项目的主要目的是更好地了解全反式维甲酸和AUR在皮肤鳞状细胞癌发展中的作用。我们的总体假设是，ATRA和AUR联合使用比单独使用任何一种药物都更有效，因为ATRA可以抑制STAT3信号转导，AUR可以抑制NF-：B通路和其他途径。STAT3是一种控制细胞增殖和存活的转录因子，在调节细胞凋亡、增殖、运动和血管生成方面发挥着重要作用，而这些都是恶性肿瘤的标志。我们的实验室和其他实验室已经证明，STAT3活性在几种恶性细胞类型中是构成的，并且是皮肤鳞状细胞癌启动、促进和发展为更恶性表型所必需的。核因子-B是一种生存信号转录因子，也参与许多癌症的恶性表型，包括鳞状细胞癌。我们的初步结果显示，在严重联合免疫缺陷(SCID)小鼠原位肿瘤形成模型中，ATRA+AUR联合应用可抑制来自人皮肤SCC细胞系SRB12-p9(P9WT)的肿瘤生长。我们将首先研究更大剂量的ATRA 1AUR对SCID小鼠肿瘤体积的影响。我们将在药物抑制STAT3的背景下比较AUR治疗的效果(ATRA治疗)和遗传抑制STAT3的效果(STAT3的显性负作用形式的稳定表达；S3DN细胞)。将详细分析肿瘤的恶性特性以及抑制STAT3和NF-：B通路。我们将通过单独和联合在P9WT SCC细胞中从基因上阻断STAT3通路(S3DN细胞)和NF-：B通路(shRNA介导的NF-：B击倒)来进一步验证我们的假设。由此产生的途径被抑制的细胞的致瘤特性将被确定。 与公共健康相关：该项目的目标是提供证据，证明全反式维甲酸(一种维生素A衍生物)与柑橘衍生化合物(极光烯)的结合将增强预防非黑色素瘤皮肤癌的效果。这个项目与人类健康的相关性是，非黑色素瘤皮肤癌每年困扰着100多万美国人，并可能导致虚弱的疾病甚至死亡。此外，某些人群，如实体器官移植患者(截至2006年为173,000人)、艾滋病毒患者和其他免疫功能受损的个人患这些类型癌症的风险大大增加。因此，在限制毒性的同时提高有效性的新的预防战略将是可取的。

DESCRIPTION (provided by applicant): There is an increasing need for safe, long-term preventive treatments for non-melanoma skin cancer (NMSC), which is a particular threat to high risk groups such as the growing populations of immunocompromised solid organ transplant patients, HIV patients, and elderly non-Hispanic Caucasians. We have shown that a combination of the well-characterized chemopreventive vitamin A metabolite, all-trans retinoic acid (ATRA), with the bioactive dietary agent auraptene (AUR), can synergistically or supra-additively suppress skin squamous cell carcinoma (SCC) tumor growth in a mouse xenograft model. A long-term goal of our research is to develop effective chemopreventive treatments for epithelial cancers. In keeping with this goal, the primary aim of this project is to gain a better understanding of the effects of ATRA, and AUR on the development of skin SCC. Our overall hypothesis is that the ATRA + AUR combination is more effective than either agent alone due to the ability of ATRA to suppress Stat3 signaling, and AUR to suppress the NF-:B pathway and other pathways. Stat3 is a transcription factor that controls cell proliferation and survival, and is important in the regulation of apoptosis, proliferation, motility, and angiogenesis, all hallmarks of malignancy. Our laboratories and others have shown that Stat3 activity is constitutive in several malignant cell types and is required for initiation, promotion and progression to a more malignant phenotype in skin SCC. NF-:B is a survival signaling transcription factor also involved in the malignant phenotype of many cancers, including SCCs. Our preliminary results show that the ATRA+AUR combination suppresses the growth of tumors derived from the human skin SCC cell line SRB12-p9 (P9 WT), in the severe combined immunodeficient (SCID) mouse orthotopic tumorigenesis model. We will first examine the effects of a wider range of doses of ATRA 1 AUR against tumor volume in SCID mice. We will compare the effects of AUR treatment in the context of pharmacological suppression of Stat3 (ATRA treatment) to genetic suppression of Stat3, (stable expression of a dominant negative acting form of Stat3; S3DN cells). Tumors will be analyzed in detail for malignant properties and for suppression of Stat3 and NF-:B pathways. We will further verify our hypothesis by genetically blocking the Stat3 pathway (S3DN cells) and the NF-:B pathway (shRNA mediated knockdown of NF-:B), alone and in combination, in the P9WT SCC cells. The tumorigenic properties of the resulting pathway suppressed cells will be determined. PUBLIC HEALTH RELEVANCE: The goal of this project is to provide evidence that the combination of all-trans retinoic acid, a vitamin A derivative, with a citrus derived compound, auraptene, will provide an enhanced effect to prevent non- melanoma skin cancer development. The relevance of this project to human health is that non-melanoma skin cancer afflicts more than one million Americans every year, and can result in debilitating disease and even death. Furthermore, certain populations, such as solid organ transplant patients (> 173,000 as of 2006), HIV patients, and other immunocompromised individuals are at a greatly increased risk for these types of cancers. Novel prevention strategies that increase effectiveness while limiting toxicity would therefore be desirable.