MONOCYTES TO ASSESS GENOMIC ACTION OF CALCITRIOL

描述（摘自申请人摘要） 1，25-二羟维生素D3（1，25（OH）2D3）的生物学效应通过以下途径介导： 基因和非基因机制。尽管基因机制在 在1，25（OH）2D3介导的高钙血症中，非基因组机制，其特征在于 通过增加胃肠道对Ca2+的吸收， 重要.血清和尿钙水平及其他骨标志物 周转率常规用于监测接受1，25（0H）2D3治疗的患者 因为高钙血症是剂量限制性毒性， 测量在大多数临床中心是容易获得的。然而，在这方面， 高钙血症和其他骨转换标志物不适合作为特异性 由于所涉及的机制和基因组的双重性质， 1，25（OH）2D3的作用与其高钙作用无关。的 抗增殖、分化和诱导凋亡的特性 1，25（OH）2D3是由于基因组反应，可用于治疗 以细胞过度增殖为特征的人类疾病， 癌这导致需要鉴定基因组的特异性标记物， 1，25（OH）2D3在人体内的作用 该项目描述了一些研究，其具体目的是确定 外周血单核细胞可用作移植物中的替代组织。 评估1，25（OH）2D3在接受以下剂量的患者中的基因组效应： 超过4微克/天。单核细胞是合适的候选者， 研究，因为他们是高度敏感的基因组行动， 1，25（OH）2D3，很容易从其他外周血单核细胞中纯化 细胞，并且可以使用相对简单，非侵入性的 技术.将通过以下方法评估血液单核细胞中的基因组作用： 测量众所周知的1，25（OH）2D3-应答性的mRNA和酶活性， 基因：24-羟化酶，胞苷脱氨酶，果糖-1，6-二磷酸酶， 碱性磷酸酶和脂氧合酶，以及VDR（维生素D 受体）和p21，并与母体药物的血浆水平相关， 代谢物（通过高效液相色谱法测量）。的 1，25（OH）2D3基因组作用的多效性，以及 这些酶活性相对缺乏特异性，导致 不同的时间过程中的多个标志物在其表达相对于 药品监督管理总局.这些药代动力学：药效学研究将 为1，25（OH）2D3的作用提供了新的见解。

DESCRIPTION (Taken from the applicant's Abstract) Biologic effects of 1,25-dihydroxyvitamin D3 (1,25(0H)2D3) are mediated via genomic and non-genomic mechanisms. Although genomic mechanisms play a role in 1,25(0H)2D3-mediated hypercalcemia, non-genomic mechanisms, characterized by increased gastrointestinal absorption of Ca2+, are probably more important. Serum and urinary calcium levels and other markers of bone turnover are routinely used to monitor patients on 1,25(0H)2D3 therapy because hypercalcemia is the dose limiting toxicity and tests for calcium measurement are readily available at most clinical centers. However, hypercalcemia and other bone turnover markers are unsuitable as specific markers because of the dual nature of the mechanisms involved and genomic effects of 1,25(0H)2D3 do not correlate with its hypercalcemic effects. The anti-proliferative, differentiation and apoptosis-induction properties of 1,25(0H)2D3 are due to genomic responses, which can be exploited to treat human diseases characterized by cellular hyperproliferation as seen in cancer. This has led to the need to identify specific markers of genomic action of 1,25(0H)2D3 in humans. This project describes studies whose specific aims are to determine if peripheral blood monocytes can be used as a surrogate tissue in the assessment of genomic effects of 1,25(0H)2D3 in patients receiving doses in excess of 4 micrograms/day. Monocytes are suitable candidates for these studies because they are highly sensitive to the genomic action of 1,25(0H)2D3, are readily purified from other peripheral blood mononuclear cells, and can be sampled repeatedly using relatively simple, non-invasive techniques. The genomic action in blood monocytes will be assessed by measuring mRNA and enzyme activities of well-known 1,25(0H)2D3-responsive genes: 24-hydroxylase, cytidine deaminase, fructose-1,6-diphosphatase, alkaline phosphatase and lipoxygenases, in addition to VDR (a vitamin D receptor) and p21 and related to plasma levels of parent drug and metabolites (measured by high performance liquid chromatography). The pleiotropic nature of the genomic action of 1,25(0H)2D3, together with the relative lack of specificity of these enzyme activities, results in different time courses of multiple markers in their expression relative to drug administration. These pharmacokinetic:pharmacodynamic studies will provide new insight into the effects of 1,25(0H)2D3.