Neutral Endopeptidase inactivation in advanced prostate

描述（由申请人提供）：大量研究表明，神经肽生长因子有助于前列腺癌的发生和进展。中性内肽酶24.11（Neutral endopeptidase 24.11，NEP，CALLA，CD 10）是一种细胞表面肽酶，其使多种与前列腺癌有关的神经肽失活，包括蛙皮素、内皮素-1（ET-1）和神经降压素。我们首先报道了NEP表达在原发性和转移性前列腺癌的一个亚组中降低，并且NEP表达部分受雄激素调节，并且随着雄激素戒断而降低。在我们过去的研究中，我们已经表征了NEP基因的雄激素调节，证明了使用外源性重组NEP或细胞表面NEP的过表达替代NEP抑制前列腺癌细胞生长，细胞迁移和致瘤性，并确定了NEP发挥肿瘤抑制作用的至少三种不同机制，包括1）NEP的神经肽底物的催化失活，2）与磷脂酰肌醇3-激酶（P13-K）蛋白间接缔合并抑制P13-K与粘着斑激酶（FAK）的相互作用，和3）与PTEN肿瘤抑制基因蛋白直接缔合并稳定。这些数据表明，NEP蛋白正常发挥调节前列腺上皮细胞生长的功能，并且NEP表达的缺失可能有助于前列腺癌的生长和进展。在此更新申请中，我们建议继续定义NEP在前列腺癌细胞中抗肿瘤作用的机制，更彻底地破译NEP表达的调节，并研究NEP作为使用新型融合蛋白的治疗的潜力，其中NEP连接到特异性靶向前列腺癌细胞的单克隆抗体。这些拟议中的研究应提供重要的新知识的多功能的细胞表面肽酶与NEP作为原型，更清楚地定义参与NEP在前列腺癌的发展和进展。

DESCRIPTION (provided by applicant): Numerous studies indicate that neuropeptide growth factors contribute to the development and progression of prostate cancer. Neutral endopeptidase 24.11 (NEP, CALLA, CD10) is a cell-surface peptidase that inactivates a variety of neuropeptides implicated in prostate cancer, including bombesin, endothelin-1 (ET-1) and neurotensin. We first reported that NEP expression is decreased in a subset of primary and metastatic prostate cancers, and that NEP expression is in part regulated by androgen and decreases with androgen-withdrawal. In our research over this past grant period, we have characterized the androgen regulation of the NEP gene, demonstrated that replacement of NEP using either exogenous recombinant NEP or overexpression of cell-surface NEP inhibits prostate cancer cell growth, cell migration and tumorigenicity, and have identified at least three distinct mechanisms by which NEP exerts a tumor suppressive effect, including 1) catalytic inactivation of NEP's neuropeptide substrates, 2) indirectly associating with phosphatidylinositol 3-kinase (P13-K) protein and inhibiting the interaction of P13-K with focal adhesion kinase (FAK), and 3) directly associating with and stabilizing the PTEN tumor suppressor gene protein. These data suggest that the NEP protein normally functions to regulate prostate epithelial cell growth, and that loss of NEP expression may contribute to prostate cancer growth and progression. In this renewal application, we propose to continue to define the mechanisms of NEP anti-tumor effects in prostate cancer cells, to more thoroughly decipher the regulation of NEP expression, and to study the potential of NEP as therapy using a novel fusion protein in which NEP is linked to a monoclonal antibody which specifically targets prostate cancer cells. These proposed studies should provide significant new knowledge on the multiple functions of cell-surface peptidases with NEP as a prototype, and more clearly define the involvement of NEP in the development and progression of prostate cancer.