Hector Suzanne, Porter Carl W, Kramer Debora L, Clark Kimberly, Prey Joshua, Kisiel Nicholas, Diegelman Paula, Chen Ying, Pendyala Lakshmi
Department of Medicine, Roswell Park Cancer Institute, Buffalo, New York 14263, USA.
Mol Cancer Ther. 2004 Jul;3(7):813-22.
A great deal of experimental evidence connects induction of polyamine catabolism via spermidine/spermine N1-acetyltransferase (SSAT) to antiproliferative activity and apoptosis. Following our initial observation from gene expression profiling that platinum drugs induce SSAT, we undertook this present study to characterize platinum drug induction of SSAT and other polyamine catabolic enzymes and to examine how these responses might be enhanced with the well-known inducer of SSAT and clinically relevant polyamine analogue, N1,N11-diethylnorspermine (DENSPM). The results obtained in A2780 ovarian cancer cells by real-time quantitative RT-PCR and Northern blot analysis show that a 2-hour exposure of A2780 cells to platinum drugs induces expression of SSAT, a second SSAT (SSAT-2), spermine oxidase, and polyamine oxidase in a dose-dependent manner. At equitoxic doses, oxaliplatin is more effective than cisplatin in SSAT induction. The most affected enzyme, SSAT, increased 15-fold in mRNA expression and 2-fold in enzyme activity. When combined with DENSPM to further induce SSAT and to enhance conversion of mRNA to activity, oxaliplatin increased SSAT mRNA 50-fold and activity, 210-fold. Polyamine pools declined in rough proportion to levels of SSAT induction. At pharmacologically relevant oxaliplatin exposure times (20 hours) and drug concentrations (5 to 15 micromol/L), these responses were increased even further. Combining low-dose DENSPM with oxaliplatin produced a greater than additive inhibition of cell growth based on the sulforhodamine-B assay. Taken together, the findings confirm potent induction of polyamine catabolic enzymes, such as SSAT by platinum drugs, and demonstrate that these biochemical responses as well as growth inhibition can be potentiated by co-treatment with the polyamine analogue DENSPM. With appropriate in vitro and in vivo optimization, these findings could lead to clinically relevant therapeutic strategies.
大量实验证据表明,通过亚精胺/精胺N1-乙酰基转移酶(SSAT)诱导多胺分解代谢与抗增殖活性和细胞凋亡相关。基于我们最初从基因表达谱观察到铂类药物可诱导SSAT,我们开展了本研究,以表征铂类药物对SSAT和其他多胺分解代谢酶的诱导作用,并研究如何使用著名的SSAT诱导剂及临床相关多胺类似物N1,N11-二乙基亚精胺(DENSPM)来增强这些反应。通过实时定量逆转录聚合酶链反应(RT-PCR)和Northern印迹分析在A2780卵巢癌细胞中获得的结果表明,将A2780细胞暴露于铂类药物2小时可剂量依赖性地诱导SSAT、第二种SSAT(SSAT-2)、精胺氧化酶和多胺氧化酶的表达。在等效毒性剂量下,奥沙利铂在诱导SSAT方面比顺铂更有效。受影响最大的酶SSAT,其mRNA表达增加了15倍,酶活性增加了2倍。当与DENSPM联合使用以进一步诱导SSAT并增强mRNA向活性的转化时,奥沙利铂使SSAT mRNA增加了50倍,活性增加了210倍。多胺池的下降与SSAT诱导水平大致成比例。在药理学相关的奥沙利铂暴露时间(20小时)和药物浓度(5至15微摩尔/升)下,这些反应进一步增强。基于磺基罗丹明B试验,将低剂量DENSPM与奥沙利铂联合使用对细胞生长产生了大于相加的抑制作用。综上所述,这些发现证实了铂类药物可有效诱导多胺分解代谢酶,如SSAT,并表明通过与多胺类似物DENSPM联合治疗可增强这些生化反应以及生长抑制作用。经过适当的体外和体内优化,这些发现可能会带来临床相关的治疗策略。