Neutral Endopeptidase inactivation in advanced prostate

描述(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展和进展。中性内肽酶24.11(NEP，CALLA，CD10)是一种细胞表面多肽酶，可灭活与前列腺癌有关的多种神经肽，包括蛙皮素、内皮素-1(ET-1)和神经降压素。我们首次报道了NEP在原发癌和转移性前列腺癌中的表达降低，并且NEP的表达在一定程度上受雄激素的调节，并随着雄激素的减少而减少。在我们过去一段时间的研究中，我们研究了NEP基因的雄激素调节，证明了使用外源重组NEP替换NEP或过表达细胞表面NEP可抑制前列腺癌细胞的生长、细胞迁移和致瘤性，并已确定NEP至少通过三种不同的机制发挥抑癌作用，包括1)催化NEP的神经肽底物失活，2)间接与磷脂酰肌醇3-激酶(P13-K)蛋白结合并抑制P13-K与粘着斑激酶(FAK)的相互作用，以及3)直接与PTEN抑癌基因蛋白结合并稳定PTEN抑癌基因蛋白。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，NEP表达的缺失可能有助于前列腺癌的生长和进展。在这一新的应用中，我们建议继续确定NEP在前列腺癌细胞中的抗肿瘤作用的机制，更彻底地破译NEP的表达调控，并使用一种新型的融合蛋白来研究NEP作为治疗的可能性，在该融合蛋白中，NEP与一种针对前列腺癌细胞的单抗相连。这些拟议的研究将为以NEP为原型的细胞表面肽酶的多种功能提供重要的新知识，并更清楚地定义NEP参与前列腺癌的发生和发展。

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.