Progranulin signaling in bladder cancer

描述(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例估计死亡。无论采用何种治疗方法，膀胱癌往往会复发和转移，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至关重要。我们已经证实，生长因子原颗粒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，并证明原颗粒作为一种自分泌生长因子发挥作用。此外，我们还发现浸润性膀胱癌中原颗粒蛋白的表达高于正常膀胱。总而言之，我们的结果支持这样的假设，即原颗粒在膀胱癌的发生和发展中可能作为一种自分泌生长因子发挥关键作用。尽管与生长控制和癌症有很强的联系，但原颗粒的作用模式仍然缺乏特征。我们发现粘着斑激酶PYK2被原颗粒激活，并在膀胱癌组织中表达增加。相反，基因敲除原颗粒抑制了转移性膀胱癌细胞的运动和非锚定生长。这表明原颗粒可能在侵袭性(高运动性)表型中起关键作用。通过下拉实验和蛋白质组学的研究，我们首次确定了Drebrin是一种与原颗粒相互作用的膜蛋白。Drebrin是一种肌动蛋白结合蛋白，参与细胞黏附、运动和钙信号传导。因此，我们假设Drebrin可能是参与前颗粒信号传递的超分子复合体的一部分。我们将通过以下具体目标来验证我们的假设并实现这一应用的目标：[1]确定原颗粒在膀胱癌细胞中的作用机制。[2]研究新的原颗粒蛋白相互作用蛋白Drebrin在调控膀胱癌细胞运动和侵袭中的作用。[3]研究原颗粒蛋白、Pyk2和Drebrin在膀胱癌形成和发展中的体内作用。预期的结果不仅将为更好地了解调节肿瘤细胞运动的机制提供新的信息，而且还将为了解原颗粒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。一旦表征了原颗粒通路在膀胱癌形成和发展中的作用，这些研究将极大地有助于确定膀胱癌治疗干预的新靶点。此外，原颗粒蛋白、Pyk2和Drebrin可能被证明是膀胱癌的新的诊断和/或预后的生物标志物。

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.