Urokinase Receptor Integrin Interactions in Lung Cancer

描述（由申请人提供）：癌症进展和癌症死亡的关键决定因素是肿瘤细胞存活、生长、侵入基质基质和转移的能力。侵袭和转移取决于降解周围细胞外基质所需的蛋白水解酶和重组细胞-细胞和细胞-基质附着所需的粘附分子的协调和时间表达。强有力的间接证据表明，蛋白酶尿激酶、其受体 (uPAR) 和 b1 整合素对肺癌进展很重要。之前的研究表明，uPAR 是一种 b1 整合素配体，可以改变整合素基质的结合和信号传导，并促进肿瘤细胞在体外和体内的迁移。该提案将检验以下假设：uPAR 作为肿瘤细胞存活和转移的强效剂，通过与 b1 整联蛋白相互作用来协调 MMP 上调并改变有利于基质侵袭的细胞骨架组织。首先，扩展先前的工作，uPAR 中介导与 b1 整联蛋白 a3b1 和 a5b1 相互作用的关键氨基酸残基将得到完全确定。基于此信息，破坏 uPAR/b1 整合素相互作用的肽将被用作原发性肺癌细胞中 uPAR/整合素信号传导的诊断测试。其次，使用无法结合特定 b1 整合素的 uPAR 点突变体，将定义由 uPAR/整合素相互作用引发的基质接合改变和 MMP 上调的分子机制。最后，将野生型或 uPAR 沉默、GFP 标记的 H1299 细胞原位注射到无胸腺裸鼠的肺部，并对肺癌生长、淋巴结转移和血管生成进行量化和比较。将检查用无法结合 a3b1 或 a5b1 的 uPAR 突变体重建的细胞，以确定 uPAR/整合素相互作用而不是单独的 uPA 结合对于体内 uPAR 依赖性肿瘤进展是否至关重要。总之，这些实验应阐明 uPAR 对肿瘤进展促进作用的机制基础，确定 uPAR/整合素相互作用是否是一个引人注目的治疗靶点，并确定是否可以定义依赖于 uPAR 恶性潜能的肺癌诊断测试。

DESCRIPTION (provided by applicant): Critical determinants of cancer progression and death from carcinomas are the capacity of tumor cells to survive, grow, invade their matrix stroma, and metastasize. Invasion and metastasis depend on the coordinated and temporal expression of proteolytic enzymes necessary to degrade the surrounding extracellular matrix and of adhesion molecules to reorganize cell-cell and cell-matrix attachments. Strong circumstantial evidence indicates that the protease urokinase, its receptor (uPAR), and b1 integrins are important to lung cancer progression. And prior work indicates that uPAR is a b1 integrin ligand, modifying integrin matrix engagement and signaling, and promoting tumor cell migration in vitro and in vivo. This proposal will test the hypothesis that uPAR acts as a strong agent of tumor cell survival and metastasis, acting through interactions with b1 integrins to coordinate MMP upregulation and alter cytoskeletal organization favoring matrix invasion. First, extending prior work, critical amino acid residues in uPAR that mediate interactions with the b1 integrins a3b1 and a5b1 will be fully established. Based on this information, peptides which disrupt uPAR/b1 integrin interactions will be exploited as a diagnostic test for uPAR/integrin signaling in primary lung cancer cells. Secondly, using uPAR point mutants unable to bind specific b1 integrins, the molecular mechanisms of altered matrix engagement and MMP upregulation initiated by uPAR/integrin interactions will be defined. Finally, wild type or uPAR silenced, GFP tagged H1299 cells will be injected either orthotopically into lungs of athymic nude mice and lung cancer growth, node metastasis, and angiogenesis quantified and compared. Cells reconstituted with uPAR mutants unable to bind either a3b1 or a5b1 will be examined to determine if uPAR/integrin interactions rather than uPA binding alone is crucial to uPAR-dependent tumor progression in vivo. Together, these experiments should clarify the mechanistic basis for the promoting role of uPAR on tumor progression, establish whether uPAR/integrin interactions are a compelling therapeutic target, and determine whether a diagnostic test for lung cancers dependent on uPAR for their malignant potential can be defined.