FOLATE RECEPTOR AS MARKER AND TARGET IN CANCER THERAPY

叶酸是正常生长所必需的水溶性维生素， 发展 抗叶酸剂是抗生素，抗肿瘤塑料， 免疫抑制药。 例如，甲氨蝶呤 一直是治疗儿童急性白血病的中流砥柱， 40年，也用于治疗自身免疫性疾病和哮喘。 我们的长期目标是获得一个彻底的了解叶酸 稳态，并应用这些信息，以更好地利用和刺激 抗叶酸剂的合成 具体目标包括： 完整了解叶酸通过特定的叶酸积累 受体，其是G-PI连接的蛋白。 这包括受体如何 转运叶酸穿过细胞膜，运输是如何与 叶酸和聚谷氨酸的合成以及如何作用和周转（合成 和降解）受到调节。 积累与代谢 5甲基[3 H]四氢叶酸，天然存在的放射性标记配体 血清叶酸，通过在体外生理叶酸（~ 5 nM）中生长的细胞， hplc跟踪 抗叶酸剂的作用，叶酸的终产物 介导的反应和激素或化合物已知的影响 糖基磷脂酰肌醇连接的蛋白以及糖基磷脂酰肌醇连接的蛋白的抑制剂， 分析叶酸聚谷氨酸合成酶。 的合成 受体及其mRNA的研究，采用免疫沉淀技术， 使用针对受体的特定部分的抗体和RNA印迹 使用受体的全长cDNA探针。 除了这些基本 研究，开发一种受体的放射免疫测定法将允许 测量释放的受体的血浆浓度，其可以是 一个持续性或复发性疾病的标志物， 抗体作为药剂定位和/或递送细胞毒性 过度表达受体的肿瘤。

Folates are water soluble vitamins essential for normal growth and development. Antifolates are antibiotics, antineoplastics, antiinflammatory and immunosuppressive drugs. For example, methotrexate has been a mainstay in the treatment of acute leukemia of childhood for > 40 years and also used in the treatment of autoimmune disease and asthma. Our long-term objectives are to obtain a thorough understanding of folate homeostasis and apply this information to better the use of and stimulate the synthesis of antifolates. Specific aims include obtaining a more complete understanding of folate accumulation via a specific folate receptor which is a G-PI linked protein. This includes how the receptor translocates folates across the membrane, how transport is related to folate polyglutamate synthesis and how the function and turnover (synthesis and degradation) of the receptor is regulated. Accumulation and metabolism of 5methyl[3H]tetrahydrofolate, radiolabelled ligand of naturally occurring serum folate, by cells grown in physiological folate (~5nM) in vitro is monitored by HPLC. The effects of antifolates, end products of folate mediated reactions and hormones or compounds known to effect glycosylphosphatidylinositol linked proteins as well as inhibitors of folate polyglutamate synthetase are analyzed. The synthesis of the receptor and its mRNA are studied using immunoprecipitation techniques using antibodies against specific moieties of the receptor and RNA blotting using full length cDNA probes for the receptor. In addition to these basic studies, developing a radioimmunoassay for the receptor will allow measurement of plasma concentrations of the released receptor, which may be a marker for persistent or recurrent disease or perhaps even using antibodies as a pharmaceutical agent to localize and/or deliver cytotoxic agents to tumors over-expressing the receptor.