PTH-related peptide and vit D in prostate cancer growth

描述(申请人提供)：前列腺癌是美国男性癌症死亡的最大原因；许多前列腺癌患者在确诊时有转移性疾病。维生素D缺乏是前列腺癌的风险因素，在前列腺癌患者的临床试验中，1，25-二羟基维生素D3(1,250，维生素D的激素活性形式)和非钙化类似物显示出治疗效果。前列腺癌细胞产生许多生长因子，包括甲状旁腺激素相关蛋白(以前称为多肽，PTHrP)。我们发现，PTHrP过表达增加了前列腺癌细胞：(A)增殖；(B)与细胞外基质蛋白I型和IV型胶原、层粘连蛋白和纤维连接蛋白的黏附；(C)在层粘连蛋白和I型胶原上的迁移；(D)对重建的基底膜Matrigel的侵袭；(E)非贴壁细胞生长；(F)细胞表面亲侵袭整合素a6|34的表达；以及(G)体内异种移植的生长。1,250对这些参数有相反的影响，并下调PTHrP基因的表达。正如使用siRNAs显示的那样，1,250的抗增殖和抗侵袭作用需要PTHrP和整合素04的表达。因此，我们假设(A)PTHrP通过上调侵袭前整合素的表达促进前列腺癌的转移，以及(B)维生素D的治疗益处是通过下调PTHrP基因的表达和直接影响整合素的表达来实现的。该项目通过追求三个目标，试图了解前列腺癌细胞中PTHrP、维生素D和整合素a6p4之间的关系。(1)将利用siRNAs和整合素启动子缺失/瞬时转染法研究PTHrP和维生素D调节整合素a634表达的途径。由于整合素a6(34)增加了癌症的侵袭性，我们将通过免疫沉淀来确定维生素D是否将a6的关联从(34改变为31。(2)将利用裸鼠模型研究PTHrP和整合素(34)在前列腺癌细胞生长和骨转移中的作用，以及联合维生素D治疗的效果。(3)维生素D调节PTHrP基因表达的反应元件将通过PTHrP基因启动子缺失和瞬时转染实验进行鉴定。了解PTHrP、维生素D和前侵袭性整合素表达之间的关系，以及涉及的分子途径，应该会导致开发新的联合治疗方法来管理前列腺癌。

DESCRIPTION (provided by applicant): Prostate cancer is the largest cause of male cancer death in the United States; many prostate cancer patients have metastatic disease at diagnosis. Vitamin D deficiency is a risk factor for prostate cancer, and 1,25-dihydroxyvitarhin D3 (1,250, the hormonally active form of vitamin D) and noncalcemic analogues have shown therapeutic benefits in clinical trials with prostate cancer patients. Prostate cancer cells produce many growth factors, including parathyroid hormone-related protein (formerly peptide, PTHrP). We show that PTHrP overexpression increases prostate cancer cell (a) proliferation; (b) adhesion to the extracellular matrix proteins collagen types I and IV, laminin, and fibronectin; (c) migration onto laminin and collagen type I; (d) invasion of Matrigel, a reconstituted basement membrane; (e) anchorage-independent cell growth; (f) cell surface expression of the pro-invasive integrin a6|34; and (g) xenograft growth in vivo. 1,250 exerts opposite effects on all these parameters, and downregulates PTHrP gene expression. Both PTHrP and integrin 04 expression are required for the anti-proliferative and anti-invasive effects of 1,250, as shown using siRNAs. We thus hypothesize that (a) PTHrP facilitates prostate cancer metastasis by upregulating pro-invasive integrin expression, and (b) the therapeutic benefits of vitamin D are mediated via both downregulatipn of PTHrP gene expression and a direct effect on integrin expression. This project seeks to understand the relationship between PTHrP, vitamin D and integrin a6p4 in prostate cancer cells, by pursuing three Aims. (1) The pathways via which PTHrP and vitamin D regulate integrin a634 expression will be investigated using siRNAs and integrin promoter deletions/transient transfection assays. Since integrin a6(34 increases cancer aggressiveness, we will determine by immunoprecipitation whether vitamin D alters the association of a6 from (34 to 31. (2) The role of PTHrP and integrin (34 in prostate cancer cell growth and bone metastasis, and the effect of concomitant vitamin D treatment, will be studied in vivo using a nude mouse model. (3) The vitamin D response elements via which vitamin D regulates PTHrP gene expression will be identified by PTHrP gene promoter deletions and transient transfection assays. Understanding the relationship between PTHrP, vitamin D, and pro-invasive integrin expression, and the molecular pathways involved, should lead to the development of new combinatorial therapeutic approaches to manage prostate cancer.