25-hydroxy-D3 as a possible chemopreventive agent for breast cancer

性状（由申请方提供）：1，25（OH）2 D3是维生素D作用的活性代谢物，作为维生素D受体的配体。虽然在生理浓度下，它可能没有毒性，但在此水平下也没有任何化学预防活性。在较高浓度下，它是高钙的。最近发现1a（OH）ase（CYP27B1）在多种维生素D靶组织中表达，25（OH）D3可能被用作血清中的主要天然保护剂。它可以在细胞内被CYP27 B1转化为活性的1，25（OH）2D3，使其在细胞生长调节和分化中发挥作用。在这项研究中，我们将测试的假设，25（OH）D3维持细胞分化，并抑制转化为1，25（OH）2D3在正常乳腺上皮细胞表达CYP27 B1。长期目标是开发25（OH）D3作为乳腺癌的天然化学预防剂。由于25（OH）D3转化为活性1，25（OH）2D3的关键是乳腺上皮细胞中的维生素D代谢酶CYP 27 B1，因此我们设计了两个具体目标来系统地解决该项目中的这一问题：目标1。研究CYP27 B1在正常乳腺和乳腺癌上皮细胞中的表达和调控。为此，我们提出三个问题：1。CYP27 B1在正常和肿瘤乳腺上皮细胞中的表达在转录和翻译水平上是否存在差异？2. CYP27 B1的表达和调节与细胞分化有关吗？3. CYP27 B1的转录（或启动子调控）是否具有组织特异性？如果转录是组织特异性的，那么25（OH）D3在乳腺癌的化学预防和治疗中是否有潜在的用途？目标2.确定25（OH）D3在乳腺癌化学预防中的功能作用。为此，我们提出三个问题：1。25（OH）D3是否抑制乳腺上皮细胞增殖或诱导分化？2. 25（OH）D3是否抑制DMBA诱导的乳腺肺泡病变的形成，以及这种作用在病变形成的起始或促进阶段是否是选择性的？3. 25（OH）D3是否能保护正常乳腺上皮细胞免受致癌物处理诱导的转化？这项研究的结果将确立25（OH）D3在乳腺癌化学预防中的作用，并为更广泛的RO1应用奠定基础。

DESCRIPTION (provided by applicant): 1,25(OH)2 D3 is the active metabolite of vitamin D action and serves as a ligand for vitamin D receptors. Although at a physiological concentration, it may not be toxic, it also does not have any chemopreventive activity at this level. At higher concentrations it is highly calcemic. With recent discovery that 1a(OH)ase (CYP27B1) is expressed in multiple vitamin D target tissues, it is possible that 25(OH)D3 can be used as a major natural protective agent in serum. It can be converted to the active 1,25(OH)2D3 in the cells by CYP27B1, allowing its function in cell growth modulation and differentiation. In this study, we will test the hypothesis that the 25(OH)D3 maintains the cell differentiation and inhibits transformation by conversion to 1,25(OH)2D3 in normal breast epithelial cells expressing CYP27B1. The long term goal is to develop 25(OH)D3 as a natural chemopreventive agent for breast cancer. Since the key for the conversion of 25(OH)D3 to active 1,25(OH)2D3 is vitamin D metabolizing enzyme CYP27B1 in breast epithelial cells, we have designed two specific aims to systematically address this issue in this project: Aim 1. To demonstrate the expression and regulation of CYP27B1 in both normal breast and breast cancer epithelial. For this aim, we ask three questions: 1. Is there any difference in expression of CYP27B1 between normal and tumor breast epithelial cells at transcriptional and translational levels? 2. Is CYP27B1 expression and regulation related to cell differentiation? 3. Is transcription (or promoter regulation) of CYP27B1 tissue specific? If transcription is tissue specific, is there any potential use of 25(OH)D3 for breast cancer chemoprevention and therapy? Aim 2. To determine the functional role of 25(OH)D3 in breast cancer chemoprevention. For this aim, we ask three questions: 1. Does 25(OH)D3 inhibit cell proliferation or induce differentiation in breast epithelial cells? 2. Does 25(OH)D3 inhibit the mammary alveolar lesion formation induced by DMBA and whether this effect is selective during the initiation or promotion phases of lesion formation? 3. Does 25(OH)D3 protect normal breast epithelial cells against transformation induced by carcinogen treatment? Results generated from this study will establish the role of 25(OH)D3 in breast cancer chemoprevention and form the basis of a more extensive RO1 application.