MOLECULAR DETERMINANTS OF BRAIN-METASTATIC MELANOMA

描述（由申请人提供）：脑转移发生在所有癌症患者的30-40%中，是癌症发病率和死亡率的重要原因，并且其频率正在迅速增加。恶性黑色素瘤进展为高度侵袭性脑转移性疾病的机制在很大程度上仍然未知。我们实验室的主要目标是了解脑转移性黑色素瘤（BMM）的分子决定因素，并利用这些知识开发新的治疗方法来预防脑转移。由于之前的RO-1资助和使用我们的BMM细胞模型，我们已经积累了证据，证明神经营养因子受体p75 NTR和神经营养因子调节的乙酰肝素酶（HPSE）是脑转移的关键决定因素。HPSE是一种转移促进酶，其降解HS蛋白聚糖（HSPG）的硫酸乙酰肝素糖胺聚糖链（HS），HS蛋白聚糖是细胞表面-细胞外基质界面的普遍存在的组分。相比之下，最近有一种观点认为，不同的HS降解酶，细菌肝素酶-III（HeplII），可以抑制转移过程。重要的是，HPSE研究使我们进行了新的研究，分析了肝素酶- HPSE和HeplII-的差异HSPG降解，以及它们的作用如何调节BMM表型。本申请的假设是：1）HPSE通过降解特异性细胞表面和ECM HSPG调节BMM发作，2）来自HSPG的HS，取决于它们被乙酰肝素酶选择性降解，影响细胞信号传导并充当BMM的隐蔽抑制剂或促进剂，和3）HS的结构特征，被乙酰肝素酶差异性切割，与黑素瘤进展为脑转移表型相关。拟议的工作直接涉及N.C.I.提出的问题。脑肿瘤PRG报告，特别是它涉及到一个更好的了解机制的建立和脑转移的蔓延。我们将通过追求以下具体目标来测试这些假设：1。通过抑制HSPG/HS表达和功能来确定BMM调节。2.确定乙酰肝素酶和乙酰肝素酶切割的HS对BMM/脑内皮细胞信号传导的影响。3.确定乙酰肝素酶切割的HS的结构组成及其与BMM的相关性。本案无关脑转移是癌症最具破坏性的方面之一。这里概述的研究将有助于描述与恶性黑色素瘤生长和脑转移相关的分子事件，这些事件受肿瘤细胞和细胞外基质之间酶驱动的相互作用的影响。

DESCRIPTION (provided by applicant): Brain metastases, which occur in 30-40% of all cancer patients, are an important cause of cancer morbidity and mortality, and their frequency is rapidly increasing. Mechanisms responsible for malignant melanoma progression to highly aggressive brain-metastatic disease remain largely unknown. Main objective of our laboratory is to understand molecular determinants of brain-metastatic melanoma (BMM), and to use this knowledge for developing novel therapies to prevent brain metastasis. As the result of previous RO-1 funding and using our BMM cellular models, we have accumulated evidence demonstrating that the neurotrophin receptor p75NTR and neurotrophin-regulated heparanase (HPSE) are critical determinants of brain metastasis. HPSE is a metastasis - promoting enzyme which degrades the heparan sulfate glycosaminoglycan chains (HS) of HS proteoglycans (HSPG), which are ubiquitous components of the cell surface - extracellular matrix interface. In contrast, there is the recent notion that a different HS-degrading enzyme, bacterial heparinase-lll (Heplll), can inhibit the metastatic process. Importantly, HPSE studies have led us to novel investigations analyzing the differential HSPG degradation by heparanases - HPSE and Heplll - and how their action can modulate the BMM phenotype. Hypotheses for this application are: 1) HPSE modulates the BMM onset by degrading specific cell surface and ECM HSPG, 2) HS from HSPG, depending upon their selective degradation by heparanases, affect cell signaling and act as cryptic inhibitors or promoters of BMM, and 3) structural characteristics of HS, differentially cleaved by heparanases, correlate with melanoma progression to the brain-metastatic phenotype. The work proposed directly addresses issues raised by the N.C.I. Brain Tumor PRG report, in particular it relates to an improved understanding of mechanisms underlying the establishment and spread of brain metastasis. We will test these hypotheses by pursuing the following SPECIFIC AIMS: 1. To determine BMM modulation by inhibiting HSPG/HS expression and function. 2. To define effects of BMM/brain endothelial cell signaling by heparanases and heparanases- cleaved HS. 3. To determine the structural composition of HS cleaved by heparanases and their correlation with BMM. Relevance. Brain metastasis represents one of the most devastating aspects of cancer. Research outlined here will help in delineating molecular events associated with malignant melanoma growth and brain metastasis, as influenced by enzyme-driven interactions between tumor cells and extracellular matrix