STRUCTURE/FUNCTION OF METALLOPROTEINASE MT3/MMP

本提案的长期目标是了解 恶性肿瘤细胞所使用的蛋白水解机制， 细胞外基质建立的致密结构屏障， 侵袭和转移的过程。尽管手术改善 技术对原发性肿瘤，未能控制扩散， 癌细胞导致了当今大多数与癌症相关的死亡。 癌细胞侵入局部组织并转移到远处器官， 调节蛋白水解酶的表达， 降解其周围的细胞外基质屏障。 One系列 蛋白酶，称为基质降解金属蛋白酶，已经被 与癌症进展有关，因为它们能够降解 细胞外基质的所有蛋白质成分，包括 胶原蛋白、弹性蛋白和蛋白聚糖。 虽然大多数MMP 是分泌酶，最近鉴定的MT-MMP亚组包含 潜在的跨膜结构域在其C-末端，因此能够 以锚在细胞表面并形成局部蛋白水解区 在入侵细胞和它们周围的ECM屏障之间。 的 这一亚群的发现澄清了早先的怀疑， 利用固定在细胞表面的特殊蛋白水解机制 在局部侵袭和转移过程中清除通路。 MT3-MMP，a 最近添加到该亚组中，最近从一种 口腔恶性黑色素瘤组织的简并RT-PCR检测 被其他细胞和组织表达。 此外， 提出在发展侵入性 肿瘤表型 建立MT3-MMP之间的因果关系 表达和侵袭性表型，一个全面的策略是 在本申请中提出的目的是1）阐明 它从酶原到活性形式转化，2）表征它的酶促 通过以重组形式表达和分离酶， 评估MT3-MMP调节侵袭潜能的能力 肿瘤细胞在细胞外基质的体外构建体中的表达。 从MT3-MMP蛋白水解活性的表征，其 激活机制以及其赋予侵入潜力的能力 肿瘤细胞不仅应该提供一个全面的知识基础， 这种细胞膜相关金属蛋白酶在人类 恶性肿瘤，而且其作为诊断标志物或 新癌症疗法的目标。

The long term objective of this proposal is to understand the proteolytic machinery employed by malignant tumor cells to traverse the dense structural barriers established by the extracellular matrix during the invasive and metastatic process. Despite improved surgical techniques against the primary tumors, failure to control the spread of cancer cells contributes to most of the cancer related death today. Cancer cells invade local tissues and metastasize to distant organs by regulating the expression of proteolytic enzymes that allow them to degrade their surrounding extracellular matrix barriers. One family of proteinases, known as the matrix-degrading metalloproteinases, have been implicated in cancer progression by virtue of their ability to degrade all proteinaceous components of the extracellular matrix including collagens, elastin and proteoglycans. While the majority of the MMPs are secreted enzymes, the recently identified MT-MMP subgroup contain potential transmembrane domains at their C-termini and therefore be able to anchor on the cell surface and form a localized proteolytic zone between the invading cells and their surrounding ECM barrier. The discovery of this subgroup clarified earlier suspicion that tumor cells utilize special proteolytic machinery anchored on their cell surfaces to clear a pathway during local invasion and metastasis. MT3-MMP, a recent addition to this subgroup, was recently identified from an malignant oral melanoma tissue by degeneraate RT-PCR strategy and found to be expressed by other cells and tissues. Furthermore, it has been proposed to play an important role in the development of invasive phenotype of tumor. To establish a causal relationship between MT3-MMP expression and the invasive phenotype, a comprehensive strategy is proposed in this application to 1) elucidate the mechanism(s) governing its conversion from zymogen to active form, 2) characterize its enzymic properties by expressing and isolating the enzyme in recombinant forms, and 3) assess the ability of MT3-MMP to regulate the invasive potential of tumor cells in an in vitro construct of the extracellular matrix. Insights from the characterization of MT3-MMP proteolytic activity, its activation mechanism as well as its ability to confer invasive potential on tumor cells should not only provide a thorough knowledge base on the role of this cell membrane associated metalloproteinase in human malignancies, but also its potential utility as a diagnotic marker or a target for new cancer therapies.