PTH-RELATED PEPTIDE REGULATION BY VIT D IN BREAST CELLS

乳腺癌的病理学常常并发有严重的， 致命性高钙血症高钙血症的体液机制是有效的， 超过一半的乳腺癌患者。我们的长远目标 研究是控制乳腺癌相关的体液性高钙血症 甲状旁腺相关蛋白介导的恶性肿瘤（HHM （PTHrP）。维生素D3下调PTHrP基因，并抑制细胞增殖。 增殖，特性，合格的维生素D3作为一个潜在的有用的 本发明提供了用于治疗乳腺癌，包括控制PTHrP- 介导的HHM。在这个项目中，维生素D3抑制 将定义PTHrP。人PTHrP基因是一个复杂的转录调控基因， 单位，利用至少三种不同的启动子。不同细胞系 并且组织表现出不同的启动子利用模式。 使用 瞬时转染测定，每个启动子对 将在来自正常组织的细胞系中评估维生素D3， 乳腺肿瘤精确的序列元素赋予对 特定启动子内的维生素D3将通过缺失定位 映射.与这些启动子相互作用的反式作用核蛋白 元件的特征在于凝胶阻滞和核酸酶 保护测定。 迄今为止，维生素D3本身的高钙作用阻止了它的 临床应用。最近，各种非高钙维生素D3 已经合成了类似物。 非高钙维生素D3类似物 将测试它们（i）下调PTHrP基因表达的能力 和减少PTHrP分泌，和（ii）抑制细胞增殖，从而 解决这些衍生品是否发挥同样的净期望效果， 作为母体化合物，因此具有潜在价值 治疗上PTHrP已被归类为直接 早期基因家族，并具有生长因子样特性。因此 PTHrP对乳腺细胞增殖的影响将使用 反义寡核苷酸技术或反义RNA 技术. 这些研究将为临床应用奠定分子基础 非高钙维生素D3类似物作为治疗剂， PTHrP介导的HHM和细胞增殖。

The pathology of breast cancer is frequently complicated by severe and lethal hypercalcemia. A humoral mechanism for hypercalcemia is operative in more than half of breast cancer patients. The long-term objective of our research is the control of breast cancer-associated humoral hypercalcemia of malignancy (HHM) mediated by the parathyroid hormone-related protein (PTHrP). Vitamin D3 downregulates the PTHrP gene and also inhibits cell proliferation, properties that qualify vitamin D3 as a potentially useful agent in the treatment of breast cancer, including the control of PTHrP- mediated HHM. In this project, the mechanism by which vitamin D3 represses PTHrP will be defined. The human PTHrP gene is a complex transcriptional unit, utilizing at least three different promoters. Different cell lines and tissues exhibit different promoter utilization patterns. Using transient transfection assays, the responsiveness of each promoter to vitamin D3 will be assessed in cell lines derived from normal tissue and breast tumors. The precise sequence elements conferring responsiveness to vitamin D3 within a particular promoter will be located by deletion mapping. Trans-acting nuclear proteins interacting with these promoter elements will be characterized by gel retardation and nuclease protection assays. The hypercalcemic effects of vitamin D3 itself have thus far prevented its clinical application. Recently, various non-hypercalcemic vitamin D3 analogues have been synthesized. Nonhypercalcemic vitamin D3 analogues will be tested for their ability to (i) down-regulate PTHrP gene expression and decrease PTHrP secretion, and (ii) inhibit cell proliferation, thereby addressing whether these derivatives exert the same net desirable effects as the parent compound and therefore are of potential value therapeutically. PTHrP has been classified as a member of the immediate early gene family, and has growth factor-like properties. Therefore, the effect of PTHrP on breast cell proliferation will be examined, using antisense oligonucleotide technology or, alternatively, antisense RNA technology. These studies will form a molecular basis towards the clinical application of non-hypercalcemic vitamin D3 analogues as therapeutic agents targeted at both PTHrP-mediated HHM and at cell proliferation.