Suppression of Melanoma Initiation and Progression by NM23-H1

描述（由申请人提供）：皮肤恶性黑色素瘤（CMM）是最致命的皮肤癌形式，其发病率在美国和世界各地以惊人的速度增长。暴露于有害的紫外线辐射（UVR）显然是一个危险因素的疾病，证明了最近的联系之间的晒黑床的使用和显着增加黑色素瘤的发病率在年轻女性。更好地了解CMM进展为转移形式的机制可能为提高生存率提供重要的新治疗方法。转移抑制基因如NM 23-H1（小鼠中的NM 23-M1）的研究为黑色素瘤转移的分子机制提供了新的见解。该应用建立在我们的新观察基础上，即NM 23-H1是在体外对DNA施加校正活性的3 '-5'外切核酸酶，其3 '-5'外切核酸酶活性是转移抑制功能所需的，并且该蛋白质促进DNA中UVR诱导的损伤的修复。此外，为该项目开发的转基因小鼠模型首次概括了NM 23-H1在UVR诱导的CMM中的转移抑制功能。我们的研究结果支持一个模型，其中NM 23-H1表达的缺失导致基因组完整性受损和突变，这些突变驱动CMM的恶性进展。在具体目标1中，将在一种或两种亚型表达缺陷的转基因小鼠品系中确定NM 23-M1和NM 23-M2对UV辐射诱导的转移性黑素瘤的贡献。在特定目标2中，将阐明NM 23蛋白促进DNA修复途径的分子机制，并在细胞培养和肿瘤细胞解释模型系统中评估干扰这些途径对转移抑制活性的影响。具体目标3将应用强大的全基因组测序和RNA-seq的大规模平行测序技术，以确定候选的转移驱动基因组改变和基因表达谱。拟议的研究将提供第一个系统的分析特定的DNA修复和相关的途径，通过该途径转移抑制基因对抗恶性进展，以及第一次应用转基因小鼠模型来研究CMM中的转移抑制功能。我们的研究应该提供新的和关键的见解，可以追求打击黑色素瘤的先进和致命的形式。 公共卫生相关性：虽然皮肤恶性黑色素瘤（CMM）在其早期阶段通过手术治疗取得了一些成功，但一旦疾病扩散或转移到远处器官，常规治疗就无效了。本申请旨在阐明CMM转移的机制，特别是由过度暴露于破坏性紫外线辐射引起的机制。这些研究具有相当大的潜力，以改善诊断和预后的CMM患者，并提供新的见解，有效治疗疾病的最先进和致命的阶段。

DESCRIPTION (provided by applicant): Cutaneous malignant melanoma (CMM) is the most lethal form of skin cancer, and its incidence has been increasing at an alarming rate in the U.S. and around the world. Exposure to damaging ultraviolet radiation (UVR) is clearly a risk factor for the disease, borne out by the recent linkage between tanning bed usage and dramatically increased melanoma incidence in young females. Better understanding of the mechanisms by which CMM progresses to metastatic forms is likely to provide important new therapeutic approaches for improving survival rates. The study of metastasis suppressor genes, such as NM23-H1 (NM23-M1 in mouse), has provided new insights into molecular mechanisms underlying melanoma metastasis. This application builds on our novel observations that NM23-H1 is a 3'-5' exonuclease which exerts proofreading activity on DNA in vitro, that its 3'-5' exonuclease activity is required for metastasis suppressor function, and that the protein promotes repair of UVR-induced lesions in DNA. In addition, transgenic mouse models developed for this project recapitulate for the first time the metastasis suppressor function of NM23-H1 in UVR-induced CMM. Our findings support a model in which loss of NM23-H1 expression results in compromised genomic integrity and mutations that drive malignant progression in CMM. In Specific Aim 1, the contributions of NM23-M1 and NM23-M2 to UV radiation-induced metastatic melanoma will be determined in transgenic mouse strains deficient in expression of one, or both, of the isoforms. In Specific Aim 2, the molecular mechanisms underlying promotion of DNA repair pathways by NM23 proteins will be elucidated, and the impact of perturbing those pathways on metastasis suppressor activity assessed in cell culture and tumor cell explanation model systems. Specific Aim 3 will apply the powerful technologies of massively parallel sequencing for whole genome sequencing and RNA-seq to primary and metastatic melanomas to identify candidate metastasis-driving genomic alterations and gene expression profiles. The proposed studies will provide the first systematic analysis of specific DNA repair and related pathways through which a metastasis suppressor gene opposes malignant progression, as well as the first application of a transgenic mouse model to the study of metastasis suppressor function in CMM. Our studies should provide novel and critical insights that can be pursued to combat melanoma in its advanced and lethal forms. PUBLIC HEALTH RELEVANCE: While cutaneous malignant melanoma (CMM) is treated surgically with some success in its early stages, conventional treatments are ineffective once the disease has spread, or metastasized, to distant organs. This application is directed to elucidating the mechanisms that underlie metastasis in CMM, particularly that caused by overexposure to damaging ultraviolet radiation. These studies have considerable potential to improve diagnosis and prognosis of CMM patients, and to provide novel insights for effective treatments of the disease in its most advanced and lethal stages.