GLUTATHIONE AND RESISTANCE TO CANCER CHEMOTHERAPY

描述：（申请人的摘要）双官能烷基化剂（例如， 美法仑、环磷酰胺、苯丁酸氮芥）和铂类抗肿瘤化合物 (e.g.顺铂、卡铂）用于治疗多种人类疾病 恶性肿瘤 这些化合物的抗肿瘤活性是由于它们的 交联快速分裂细胞的染色体DNA的能力， 阻止肿瘤细胞增殖和诱导肿瘤细胞死亡。 的 据信这类药物的治疗功效会因其 与谷胱甘肽（g-谷氨酰半胱氨酰甘氨酸，GSH）a肽反应 存在于所有细胞中，包括肿瘤细胞。 过去发表的研究 近年来的研究表明，许多肿瘤的内在或获得性耐药性 涉及双官能烷基化剂或铂抗肿瘤化合物， 与肿瘤中GSH水平升高有关。 为了扭转这种局面， 耐药性，荷瘤动物已被给予丁噻鲁胺 磺酰亚胺（BSO）和γ-谷氨酰半胱氨酸合成酶（GCS）抑制剂 这种酶催化谷胱甘肽合成的第一步。 在这些动物中， GSH利用的持续反应导致GSH耗尽和增加 对烷基化剂和铂化合物的敏感性以及对 放射治疗 丁硫氨磺酰亚胺目前正在进行临床 作为美法仑化疗的辅助治疗。 有效消耗 肿瘤GSH需要GSH合成是有效的和一致的 抑制; GSH合成的潜在速率足够高， 即使是短暂的GCS抑制失效也会导致大量的 肿瘤GSH和恢复抵抗力。 申请人建议开发 通过阐明GSH合成的抑制作用， GCS的酶学和合成和测试新的抑制剂。 具体目的如下：（1）人类GCS与其 将表征底物和已知抑制剂。 (2)的新类似物 将合成对g-GCS具有改善的亲和力的BSO并进行体外测试 和体内。 (3)新型共价反应性过渡态抑制剂 将合成g-GCS并在体外和体内进行测试。 (4)的能力 增加基于美法仑和顺铂的 人卵巢癌异种移植物的化学疗法的特征在于： 裸鼠

DESCRIPTION: (Applicant's Abstract) Bifunctional alkylating agents (e.g., melphalan, cyclophosphamide, chlorambucil) and platinum antitumor compounds (e.g. cisplatin, carboplatin) are used to treat a wide range of human malignancies. The antitumor activity of such compounds is due to their ability to crosslink chromosomal DNA of rapidly dividing cells thereby preventing tumor cell proliferation and inducing tumor cell death. The therapeutic efficacy of such agents is believed to be reduced by their reaction with glutathione (g-glutamylcysteinylglycine, GSH) a peptide present in all cells including tumor cells. Studies published over the past several years show that the intrinsic or acquired resistance of many tumors to bifunctional alkylating agents or platinum antitumor compounds is associated with elevated levels of GSH in the tumor. To reverse such resistance, tumor-bearing animals have been administered buthionine sulfoximine (BSO), and inhibitor of gamma-glutamylcysteine synthetase (GCS) the enzyme catalyzing the first step in GSH synthesis. In such animals, the ongoing reactions of GSH utilization cause GSH depletion and increased sensitivity to alkylating agents and platinum compounds as well as to radiation therapy. Buthionine sulfoximine is currently undergoing clinical trial as an adjuvant to melphalan chemotherapy. Effective depletion of tumor GSH requires that GSH synthesis be potently and consistently inhibited; the potential rate of GSH synthesis is sufficiently high that even a brief lapse in GCS inhibition can result in substantial repletion of tumor GSH and restoration of resistance. The applicant proposes to develop improved agents for inhibition of GSH synthesis by elucidating the enzymology of GCS and by synthesizing and testing novel inhibitors. Specific aims are as follows (1) The interaction of human GCS with its substrate and known inhibitors will be characterized. (2) Novel analogs of BSO with improved affinity for g-GCS will be synthesized and tested in vitro and in vivo. (3) Novel covalently reactive transition state inhibitors of g-GCS will be synthesized and tested in vitro and in vivo. (4) The ability of novel inhibitors to increase efficacy of melphalan- and cisplatin-based chemotherapy of human ovarian cancer xenografts will be characterized in nude mice.