MOLECULAR DETERMINANTS OF BRAIN-METASTATIC MELANOMA

描述(申请人提供)：脑转移，发生在所有癌症患者的30%-40%，是癌症发病率和死亡率的重要原因，其频率正在迅速增加。恶性黑色素瘤发展为高度侵袭性脑转移疾病的机制在很大程度上仍不清楚。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，并利用这一知识开发新的治疗方法来预防脑转移。由于以前的RO-1资助和使用我们的BMM细胞模型，我们积累的证据表明，神经营养素受体p75NTR和神经营养素调节的肝素酶(HPSE)是脑转移的关键决定因素。HPSE是一种促进肿瘤转移的酶，它降解硫酸乙酰肝素蛋白多糖(HSPG)的糖胺聚糖链(HS)，它是细胞表面-细胞外基质界面上普遍存在的成分。相反，最近有一种观点认为，一种不同的HS降解酶，细菌肝素酶-11(Heplll)，可以抑制转移过程。重要的是，HPSE的研究引导我们进行了新的研究，分析了肝素酶-HPSE和Heplll-对HSPG的不同降解，以及它们的作用如何调节BMM的表型。这一应用的假设是：1)HPSE通过降解特定的细胞表面和ECM HSPG来调节BMM的发生，2)HSPG中的HS，取决于它们被肝素酶选择性地降解，影响细胞信号，并作为BMM的隐蔽抑制或促进因子，以及3)HS的结构特征，被肝素酶不同地切割，与黑色素瘤向脑转移表型的进展相关。建议的工作直接解决了N.C.I.脑瘤PRG报告提出的问题，特别是它涉及到对脑转移建立和扩散的潜在机制的更好理解。我们将通过以下具体目标来验证这些假说：1.通过抑制HSPG/HS的表达和功能来确定BMM的调节。2.明确乙酰肝素酶和肝素酶裂解HS对BMM/脑内皮细胞信号转导的影响。3.测定肝素酶裂解HS的结构组成及其与BMM的相关性。关联性。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，这些事件受到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