PTH-RELATED PEPTIDE REGULATION BY VIT D IN BREAST CELLS

乳腺癌的病理常常并发严重的和 致命性高钙血症。一种高钙血症的体液机制在 超过一半的乳腺癌患者。我们的长远目标是 研究控制乳腺癌相关体液高钙血症 甲状旁腺激素相关蛋白介导的恶性病变 (PTHrP)。维生素D3下调PTHrP基因并抑制细胞 增殖，使维生素D3有资格成为一种潜在有用的 治疗乳腺癌的药物，包括控制PTHrP- 中介HHM。在这个项目中，维生素D3抑制的机制 将定义PTHrP。人甲状旁腺素受体基因是一种复杂的转录 单位，利用至少三种不同的启动子。不同的细胞系 组织表现出不同的启动子利用模式。vbl.使用 瞬时转染法检测各启动子对 维生素D3将在来自正常组织和 乳房肿瘤。赋予应答能力的精确序列元素 特定启动子中的维生素D3将通过缺失来定位 映射。与这些启动子相互作用的反式作用核蛋白 元素将以凝胶延迟和核酸酶为特征。 保护性化验。 到目前为止，维生素D3本身的高钙化作用阻止了它的 临床应用。最近，各种非高钙维生素D3 类似物已被合成。非高钙维生素D3类似物 将测试它们是否有能力(I)下调PTHrP基因的表达 并减少PTHrP的分泌，以及(Ii)抑制细胞增殖，从而 解决这些衍生品是否产生同样的净预期效果 作为母体化合物，因此具有潜在的价值 从治疗上讲。PTHrP已被归类为立即 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被检测，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类似物作为治疗药物的靶向 PTHrP介导的HHM和AT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.