SURFACE BINDING AND ACTIVATION OF MMP9 IN TUMOR CELLS

描述：(逐字改编自调查人员的摘要)退化 由蛋白水解酶产生的细胞外基质(ECM)是 肿瘤转移。已经表明，细胞外基质的降解发生在细胞内 在侵袭的癌细胞表面和细胞-基质接触处。因此， 细胞外基质降解酶的细胞表面定位促进肿瘤细胞 移民和入侵。细胞表面的蛋白水解酶的结合也 被证明在蛋白分解活性的控制中起着中心作用 促进酶与受体、激活剂及相关物质的相互作用 底物。 基质金属蛋白酶-9(MMP9)是基质金属蛋白酶家族中的重要成员。 ECM-降解酶，与恶性进展有关。 在实验模型中的功能研究表明， 基质金属蛋白酶-9在肿瘤转移中的表达因此，基质金属蛋白酶-9是一个很有前途的靶点 寻找新的抗转移方法。 基质金属蛋白酶-9活性受酶原(pro基质金属蛋白酶-9)形式的激活调节 转化为一种具有蛋白分解活性的活性酶种类。虽然很多 已经获得了关于溶液中前基质金属蛋白酶-9激活过程的信息， 在肿瘤细胞中产生活性基质金属蛋白酶-9的机制仍然很差 明白了。新的体内和体外证据表明原基质金属蛋白酶-9结合 与肿瘤细胞表面具有高亲和力，并定位于 肿瘤-基底膜连接。始终如一地，与曲面相关联的 IV型胶原蛋白的α2(IV)链已被证明介导了 ProMMP9表达于多种肿瘤细胞系的表面。初步研究表明 原基质金属蛋白酶-9的表面结合增强了活性和催化活性 同时排除与TIMP-1的相互作用，TIMP-1是一种特异性的MMP9抑制剂。然而， 调节这些效应的确切的细胞和分子机制仍然是 要下定决心。本申请中设计的研究将(1)定义 肿瘤细胞中导致基质金属蛋白酶-9原活化的蛋白分解机制，(2) 为原基质金属蛋白酶-9的细胞表面结合奠定结构基础， (3)确定α2(IV)在细胞表面结合和激活中的作用 ProMMP9和(4)研究细胞表面结合和 原基质金属蛋白酶-9活化对细胞外基质降解和肿瘤细胞侵袭的影响结果是 这些研究将解决一个新的范式来调节原基质金属蛋白酶-9 激活，并可能提供新的和特定的工具来抑制MMP-9的活性 在人类肿瘤中。

DESCRIPTION: (adapted verbatim from the investigator's abstract) Degradation of extracellular matrices (ECM) by proteolytic enzymes is a critical aspect of tumor metastasis. It has been shown that ECM degradation occurs at the cell surface and at the cell-matrix contacts of invading cancer cells. Therefore, cell surface localization of ECM-degrading enzymes facilitates tumor cell migration and invasion. Cell surface association of proteinases has also been shown to play a central role in the control of proteolytic activity by promoting the interaction of enzymes with receptors, activators, and relevant substrates. The matrix metalloproteinase-9 (MMP-9) is a key member of the MMP family of ECM-degrading enzymes that has been associated with malignant progression. Functional studies in the experimental models have shown a direct involvement of MMP-9 in tumor metastasis. Therefore, MMP-9 represents a promising target for novel anti-metastatic approaches. MMP-9 activity is regulated by the activation of the zymogen (proMMP-9) form into an active enzyme species capable of proteolytic activity. Although much information has been gained on the process of proMMP-9 activation in solution, the mechanisms yielding active MMP-9 in tumor cells are still poorly understood. New in vivo and in vitro evidence demonstrates that proMMP-9 binds with high affinity to the surface of tumor cells and localizes at the tumor-basement membrane junctions. Consistently, a surface-associated alpha2(IV) chain of collagen IV has been shown to mediate the binding of proMMP-9 to the surface of various tumor cell lines. Preliminary studies show that surface association of proMMP-9 enhances activation and catalytic activity while precluding interactions with TIMP-1, a specific MMP-9 inhibitor. However, the precise cellular and molecular mechanisms mediating these effects remain to be determined. Studies designed in this application will (1) define the proteolytic mechanisms leading to proMMP-9 activation in tumor cells, (2) establish the structural basis for the cell surface association of proMMP-9, (3) define the role of alpha2(IV) in the cell surface binding and activation of proMMP-9 and (4) investigate the role of cell surface association and activation of proMMP-9 on ECM degradation and tumor cell invasion. The results of these studies will address a new paradigm in the regulation of proMMP-9 activation and may provide novel and specific tools to inhibit MMP-9 activity in human tumors.