Progranulin signaling in bladder cancer

描述（由申请人提供）：膀胱癌是美国最常见的癌症之一，2010 年估计有 70,530 例病例和 14,680 例死亡。无论采用何种治疗方式，膀胱癌经常复发和转移，预后极差。了解调节膀胱癌进展和侵袭生物学的细胞和分子机制对于开发针对这种毁灭性疾病的新疗法至关重要。我们已经确定生长因子颗粒体蛋白前体通过调节恶性尿路上皮细胞的运动和侵袭在膀胱癌中发挥关键作用，并证明颗粒体蛋白前体作为自分泌生长因子。此外，我们还发现，与正常膀胱相比，侵袭性膀胱肿瘤中颗粒体蛋白前体的表达增加。总的来说，我们的结果支持这样的假设：颗粒体蛋白前体可能作为自分泌生长因子在膀胱癌的形成和进展中发挥关键作用。尽管颗粒体蛋白前体与生长控制和癌症密切相关，但其作用方式仍然知之甚少。我们发现粘着斑激酶Pyk2被颗粒体蛋白前体激活，并且其在膀胱癌组织中的表达增加。相反，颗粒体蛋白前体的敲低会抑制转移性膀胱癌细胞的运动性和不依赖贴壁的生长。这表明颗粒体蛋白前体可能在侵袭性（高迁移率）表型中发挥关键作用。通过下拉实验和蛋白质组学，我们首次确定了drebrin是与颗粒体蛋白前体相互作用的膜蛋白。 Drebrin 是一种肌动蛋白结合蛋白，参与细胞粘附、运动和钙信号传导。因此，我们假设 Drebrin 可能是参与颗粒体蛋白前体信号传导的超分子复合物的一部分。我们将测试我们的假设并通过以下具体目标实现本申请的目标： [1] 确定颗粒体蛋白前体在膀胱癌细胞中的作用机制。 [2] 研究drebrin（一种新型颗粒体蛋白前体相互作用蛋白）在调节膀胱癌细胞运动和侵袭中的功能。 [3] 描述颗粒体蛋白前体、Pyk2 和 Drebrin 在膀胱癌形成和进展中的体内作用。预期的结果不仅将为更好地理解调节肿瘤细胞运动的机制提供新的信息，而且还将为颗粒体蛋白前体信号通路在调节尿路上皮肿瘤向侵袭性表型转变中的作用提供宝贵的见解。一旦确定了颗粒体蛋白前体途径在膀胱癌形成和进展中的作用，这些研究将极大地有助于确定膀胱肿瘤治疗干预的新靶点。此外，颗粒体蛋白前体、Pyk2 和 drebrin 可能被证明是膀胱肿瘤的新型诊断和/或预后生物标志物。

DESCRIPTION (provided by applicant): Bladder cancer is one of the most common cancer in the United States with 70,530 estimated cases and 14,680 estimated deaths in 2010. Regardless of the treatment modality, bladder cancer often recurs and metastasizes with very poor prognosis. Understanding the cellular and molecular mechanisms that regulate the biology of bladder cancer progression and invasion would be critical to develop new forms of treatments against this devastating disease. We have established that the growth factor progranulin plays a critical role in bladder cancer by regulating motility and invasion of malignant urothelial cells and demonstrated that progranulin acts as an autocrine growth factor. Moreover we have shown an increased expression of progranulin in invasive bladder tumors vis-¿-vis normal bladder. Collectively, our results support the hypothesis that progranulin may play a critical role as an autocrine growth factor in the establishment and progression of bladder cancer. Despite the strong connections with growth control and cancer, progranulin's mode of action is still poorly characterized. We have discovered that the focal adhesion kinase Pyk2 is activated by progranulin and its expression is increased in bladder cancer tissues. Conversely, knockdown of progranulin inhibits motility and anchorage-independent growth of metastatic bladder cancer cells. This indicates that progranulin may play a key role in the invasive (high motility) phenotype. Using pull-down experiments and proteomics we have identified for the first time drebrin as a membrane protein interacting with progranulin. Drebrin is an actin- binding protein involved in cell adhesion, motility and calcium signaling. Thus, we hypothesize that drebrin might be part of a supramolecular complex involved in progranulin signaling. We will test our hypothesis and accomplish the objectives of this application through the following specific aims: [1] Determine the mechanisms of progranulin action in bladder cancer cells. [2] Investigate the function of drebrin, a novel progranulin interacting protein, in the regulation of motility and invasion of bladder cancer cells. [3] Characterize the in vivo roles of progranulin, Pyk2 and drebrin in bladder cancer formation and progression. The expected results will provide not only novel information toward a better understanding of the mechanisms that regulate tumor cell motility but will also provide invaluable insight into the role of the progranulin signaling pathway in regulating the transition to the invasive phenotype in urothelial neoplasia. Once characterized the role of the progranulin pathway in bladder cancer formation and progression, these studies will greatly contribute to the identification of novel targets for therapeutic intervention in bladder tumors. In addition, progranulin, Pyk2 and drebrin may prove as novel diagnostic and/or prognostic biomarkers for bladder tumors.