Neuroendocrine Cell Signaling in Prostate Cancer

这项建议集中在前列腺的神经内分泌(NE)细胞及其在促进前列腺癌雄激素相互依赖的生长中所起的作用。神经内分泌(NE)细胞是一种完全分化的有丝分裂后分泌细胞，存在于正常和恶性前列腺组织中。在形态上，NE细胞可以通过其特有的神经元形态来识别，包括细胞体中存在长的神经元突起和致密的分泌小泡。在前列腺癌中，NE细胞周围的肿瘤上皮细胞的增殖指数也经常升高，这表明NE细胞通过分泌生长诱导因子而起旁分泌作用，有助于疾病的进展。这些因素中的几个已经被确定，包括5-羟色胺、促甲状腺激素(TSH)、降钙素、蛙皮素和生长抑素。NE细胞数量的增加可能是肿瘤进展的一部分。NE细胞数量的增加是肿瘤进展的一部分，可能是由于遗传和表观遗传因素的影响。晚期前列腺癌中这些数量增加的来源尚不清楚，但一些研究表明，NE细胞分别来自肿瘤内的增生性基底上皮细胞或通过去分化或转分化转化的外分泌上皮细胞。Bang事实上已经证明，前列腺癌LNCaP和PC3M细胞在加入增加细胞内环磷酸腺苷的药物后，可以被诱导分化为有丝分裂后的NE样细胞。这些实验为NE细胞来源的转分化模型提供了证据，并提示升高体内cAMP水平的生理因素可能在分化过程中发挥作用。这项研究的目的是确定促进NE细胞分化的生理因素和关键信号通路，并确定NE细胞是否分泌旁分泌信号，从而潜在地促进前列腺癌的生长。为了实现这些目标，将测试一组导致LNCaP细胞内cAMP升高的激素和多肽因子，并将分析来自最有效的分化剂的信号通路。此外，还将产生一种LacSwitch，它将引导一种组成活性形式的蛋白激酶I催化亚基的调节表达，并用于将前列腺癌细胞系分化为NE细胞。然后，这些分化的细胞将在培养和动物身上进行测试，以确定它们是否有能力促进未分化的肿瘤细胞的增殖。最后，还将研究调节分泌的信号机制。该项目的目标是阐明调节细胞分化和分泌的信号通路，并确定这些通路的关键成分，这些通路可以作为晚期雄激素非依赖性前列腺癌新疗法的分子靶点。

This proposal focuses on neuroendocrine (NE) cells of the prostate and the role they play in promoting androgen-interdependent growth of prostate tumors. Neuroendocrine (NE) cells are fully differentiated, post- mitotic secretory cells that populate both normal and malignant prostate tissue. Morphologically, NE cells can be identified by their characteristic neuronal appearance, which includes the presence of long neuritic processes and dense secretory vesicles in the cell body. In prostate tumors the proliferative index of neoplastic epithelial cells surrounding the NE cells is also frequently elevated, suggesting that the NE cells act in a paracrine fashion by secreting growth-inducing factors and contributing toe the progression of the disease. Several of these factors have been identified and include serotonin, thyroid stimulating hormone (TSH), calcitonin, bombesin, and somatostatin. Increases in the number of NE cells occur as part of tumor progression, presumably. Increases in the number of NE cells occur as part of tumor progression, presumably due to the influence of both genetic and epigenetic factors. The origin of these increased number sin later stage prostatic carcinomas is uncertain, but several studies suggest that NE cells arise from within the tumor, either from a hyperplastic basal epithelial cell or from a transformed exocrine epithelial c4ll by de-differentiation or trans-differentiation, respectively. Bang have in fact shown that the prostate tumor cells, LNCaP and PC3M, can be induced to differentiate into post-mitotic NE-like cells upon addition for agents that increase intracellular cyclic AMP. These experiments provide evidence for the transdifferentiation model of NE cell derivation and suggest that physiological factors that elevate internal cAMP levels may play a role in the differentiation process. The goal of the studies described in this proposal is to identify physiological factors and critical signaling pathways that contribute to the differentiation of NE cells and to determine whether NE cells secrete paracrine signals which potential the growth of prostate carcinomas. To accomplish these aims, a panel of hormones and peptide factors that cause elevations in intracellular cAMP in LNCaP cells will be tested, and signaling pathways emanating from the most potent differentiating agents will be analyzed. In addition, a LacSwitch will be generated that directs the regulated expression of a constitutively active form of the catalytic subunit of protein kinase I and used to differentiated prostate tumor cell lines to NE cells. These differentiated cells will then be tested both in culture and in the animal for their ability to enhance proliferation of non-differentiated tumor cells. Finally, the signaling mechanisms regulating secretion will also be examined. The goals of the project are to elucidate signaling pathways that regulate differentiation and secretion of cell cells and to identify critical components of these pathways that could serve as molecular targets for the development of novel therapies for late stage, androgen-independent prostate tumors.