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。无论何种治疗方式，膀胱癌经常复发和转移，预后很差。了解调控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形式的治疗方法至关重要。我们已经确定了生长因子前颗粒蛋白通过调节恶性尿路上皮细胞的运动和侵袭在膀胱癌中起关键作用，并证明了前颗粒蛋白作为一种自分泌生长因子。此外，我们还发现浸润性膀胱肿瘤中颗粒前蛋白的表达高于正常膀胱。总之，我们的研究结果支持了前颗粒蛋白可能作为自分泌生长因子在膀胱癌的建立和进展中发挥关键作用的假设。尽管与生长控制和癌症有很强的联系，但前颗粒蛋白的作用模式仍不清楚。我们发现局灶黏附激酶Pyk2被前颗粒蛋白激活，其在膀胱癌组织中的表达增加。相反，原颗粒蛋白的敲低抑制转移性膀胱癌细胞的运动和不依赖锚定的生长。这表明颗粒前蛋白可能在侵袭性（高运动性）表型中起关键作用。通过下拉实验和蛋白质组学，我们首次发现drebrin是一种与前颗粒蛋白相互作用的膜蛋白。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可能是参与颗粒蛋白前信号传导的超分子复合物的一部分。我们将通过以下具体目标来验证我们的假设并实现本应用的目标：[1]确定前颗粒蛋白在膀胱癌细胞中的作用机制。研究一种新型颗粒蛋白前相互作用蛋白drebrin在膀胱癌细胞运动和侵袭调控中的作用。描述蛋白前蛋白、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，而且还将为调节尿路上皮肿瘤向侵袭性表型转变的前颗粒蛋白信号通路的作用提供宝贵的见解。一旦确定颗粒蛋白前通路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，前颗粒蛋白、Pyk2和drebrin可能被证明是膀胱肿瘤新的诊断和/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.