IMPLICATIONS OF INDUCIBLE POLYAMINE CATABOLISM

这一建议是由该实验室最近的两项发现推动的，这两项发现 证明人类肿瘤细胞中多胺分解代谢的独特性： (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度限制。 细胞内多胺分解代谢中的酶活性和(2)许多人的 肿瘤细胞系，多胺分解酶，亚精胺/亚精胺 N1-乙酰转移酶(SSAT)对 多胺类似物，在其快速(小时)、大小 (100~60,000 pmol/mg/min)和细胞系间的异质性。这 一项提案将试图表征可诱导的多胺代谢在 从机制、代谢和细胞角度研究人类肿瘤细胞。 更具体地说，我们建议(A)调查SSAT的流行率 不同肿瘤细胞系之间的超诱导性和寻找共性 它，(B)从人类细胞系中提纯SSAT蛋白(已经 为一个细胞系完成)并开发针对它的抗体(正在进行中)； (C)研究对SSAT反应不同的机制基础 不同细胞系之间的诱导性；(D)评估代谢 SSAT诱导的后果及其与细胞增殖的关系； (E)在体内检测SSAT对人肿瘤移植瘤的诱导性 并将其与正常组织进行比较，(F)检测多胺 人体正常和肿瘤组织样本的分解代谢。建议数 研究将包括组织培养技术、酶分析、高效液相色谱法 方法学、蛋白质纯化技术、抗体开发和 裸鼠人体异种移植研究。归根结底，这些研究 旨在确定诱导性多胺分解代谢是否具有相关性 在监测或治疗人类恶性肿瘤方面。

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.