IMPLICATIONS OF INDUCIBLE POLYAMINE CATABOLISM

该实验室最近的两项发现促使了这一建议， 证明了多胺催化剂在人肿瘤细胞中的独特性： (1)与基于啮齿动物组织研究的教条相反，多胺 氧化而不是多胺乙酰化似乎是速率限制 在细胞内多胺催化剂中酶活性和（2）在许多人 肿瘤细胞株，多胺分解酶，精脒/精胺 N1-乙酰基转移酶（SSAT）显示出响应于 多胺类似物在其快速性（hrs）、量 (100至60，000 pmol/mg/min）和细胞系间的异质性。 这 一项提案将试图表征诱导型多胺代谢， 从机制、代谢和细胞的角度研究人类肿瘤细胞。 具体来说，我们建议（a）调查小学入学考试的普遍程度， 在各种肿瘤细胞系之间进行超诱导，并寻求 它，（B）从人细胞系（已经 完成一个细胞系），并开发抗体（正在进行中）; (c)研究对SSAT的不同反应性的机制基础 在不同细胞系之间诱导;（d）评估代谢 SSAT诱导的后果及其与细胞增殖的关系; (e)检测SSAT在人肿瘤异种移植物中的体内诱导作用 并与正常组织进行比较;（f）检测多胺 正常和肿瘤人体组织样本中的分解代谢。 拟议 研究将需要组织培养技术，酶测定，HPLC 方法学、蛋白质纯化技术、抗体开发和 在裸鼠中的人异种移植物研究。 最终，这些研究 旨在确定诱导型多胺催化剂是否与 监测或治疗人类恶性肿瘤。

This proposal was prompted by two recent findings by this laboratory which demonstrate the uniqueness of polyamine catabolism in human tumor cells: (1) contrary to dogma based on studies with rodent tissues, polyamine oxidation rather than polyamine acetylation appears to be the rate-limiting enzyme activity in intracellular polyamine catabolism and (2) in many human tumor cell lines, the polyamine catabolizing enzyme, spermidine/spermine N1-acetyltransferase (SSAT) displays an inducibility in response to polyamine analogs which is highly unique in its rapidity (hrs), magnitude (100 to 60,000 pmol/mg/min) and heterogeneity among cell lines. This proposal will attempt to characterize inducible polyamine metabolism in human tumor cells from mechanistic, metabolic and cellular perspectives. More specifically, we propose (a) to survey the prevalence of SSAT superinducibility among various tumor cell lines and seek a commonality for it, (b) to purify the SSAT protein from a human cell line (already accomplished for one cell line) and develop antibodies to it (underway); (c) to study the mechanistic basis for differential responsiveness to SSAT inducibility among different cell lines; (d) to evaluate the metabolic consequences of SSAT induction and its relationship to cell proliferation; (e) to examine in vivo SSAT inducibility of SSAT in human tumor zenografts and to compare it with that of normal tissues and (f) to examine polyamine catabolism in normal and neoplastic human tissue samples. The proposed studies will entail tissue culture techniques, enzyme assays, HPLC methodology, protein purification techniques, antibody development and human xenograft studies in nude mice. Ultimately, these studies are designed to determine whether inducible polyamine catabolism has relevance in monitoring or treating human malignancies.