FOLATE RECEPTOR AS MARKER AND TARGET IN CANCER THERAPY

叶酸是一种水溶性维生素，对正常生长和 发展。抗叶酸是抗生素，抗肿瘤， 抗炎和免疫抑制药物。例如，甲氨蝶呤 一直是儿童急性白血病治疗的中流砥柱&GT； 已有40年历史，也用于治疗自身免疫性疾病和哮喘。 我们的长期目标是彻底了解叶酸 动态平衡和应用这些信息来更好地使用和刺激 抗叶酸的合成。具体目标包括获得更多 完全了解通过特定叶酸积累的叶酸 受体是一种G-PI连接的蛋白质。这包括受体如何 将叶酸转移到膜上，运输与 叶酸多聚谷氨酸的合成及其功能和周转(合成 和降解)是受调控的。蓄积和代谢 天然放射性标记的5甲基[~3H]四氢叶酸配体 体外培养的细胞在生理叶酸(~5 nm)中生长的血清叶酸 由高效液相色谱柱监测。叶酸的最终产物--抗叶酸的作用 中介反应和已知有效的激素或化合物 糖基化磷脂酰肌醇连接蛋白及其抑制剂 对叶酸多谷氨酸合成酶进行分析。该化合物的合成 用免疫沉淀技术研究受体及其mR-NA 使用针对受体特异性部分的抗体和RNA印迹 使用全长cdna探针检测受体。除了这些基本功能之外 研究，开发一种受体的放射免疫分析将允许 测量释放的受体的血浆浓度，这可能是 是持续性或复发性疾病的标志，甚至可能是使用 抗体作为定位和/或传递细胞毒作用的药物 治疗肿瘤的药物过度表达受体。

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.