POLYAMINE ANALOG AND INHIBITOR REGULATION OF CELL CYCLE

细胞周期调控发现的治疗潜力刚刚实现，虽然它们为新的抗癌药物的开发提供了明确的机会，但它们更直接的潜力在于改善现有药物的使用。DNA损伤剂就是从这个角度研究药物的一个明显例子。根据最近的发现，我们认为在本实验室的积极参与下开发的两种多胺拮抗剂目前正在进行临床评估，它们具有先前未实现的细胞周期调节途径调节剂的潜力。这一信念是基于我们最近观察到的多胺类似物N1，N11-二乙基去甲精胺(DENSPM)和多胺酶抑制剂CGP-48664有效地激活了P53，p21，Rb途径，并诱导含有野生型P53的Malme-3M人黑色素瘤细胞G1期停滞。在含有突变型P53的SK-MEL-28黑色素瘤细胞中，DENSPM可诱导快速而大量的细胞凋亡反应。这一发现代表了多胺和细胞周期调控机制之间的第一个联系。拟议的研究将调查这些发现在人类黑色素瘤细胞系中的治疗和生物学意义。这一疾病焦点的基础是黑色素瘤在临床前系统中对这些药物的相对高度敏感性；第二阶段临床试验中黑色素瘤的靶向性；以及黑色素瘤在P53表达水平和突变频率方面往往不同于其他实体肿瘤的事实。因此，以下特定目的提出：(1)研究多胺类似物和抑制剂诱导Malme-3M黑色素瘤细胞G1期停滞的细胞周期调控通路，初步关注p53和p21的作用；(2)确定多胺类似物诱导SK-MEL-28细胞凋亡的效应分子；(3)研究与多胺相关的起始事件(S)，负责类似物和抑制剂诱导的生长抑制和凋亡；以及(4)证实体外发生的特异性类似物和抑制剂诱导的作用也在体内发生。我们相信，了解这两种多胺拮抗剂的细胞周期调节事件将有助于合理地将它们部署为抗癌药物和/或化学预防药物，同时，为人们提供新的见解，了解公认的多胺对细胞生长的要求如何与控制细胞周期进展和细胞凋亡的复杂途径相结合。

The therapeutic potential of cell cycle regulatory discoveries is just being realized and while they provide clear opportunity for the development of new and novel anticancer agents, their more immediate potential resides in improving the use of existing drugs. DNA-damaging agents are an obvious example of drugs being investigated from this perspective. On the basis of recent findings, we believe that two polyamine antagonists developed with the active involvement of this laboratory and currently undergoing clinical evaluation, have previously unrealized potential as modulators of cell cycle regulatory pathways. This belief is predicated on our recent observation that the polyamine analog N1, N11-diethylnorspermine (DENSPM) and the polyamine enzyme inhibitor CGP-48664 potently activate the p53, p21, Rb pathway and induce G1 cell cycle arrest in MALME-3M human melanoma cells containing wild- type p53. In SK-MEL-28 melanoma cells containing mutated p53, DENSPM induces a rapid and massive apoptotic response. The findings represent the first linkage between polyamines and the cell cycle regulatory machinery. The proposed studies will investigate the therapeutic and biological significance of these findings in human melanoma cell lines. This disease-focus is based on relative high sensitivity of melanoma to these agents in preclinical systems; the targeting of melanoma in Phase II clinical trials and the fact that melanoma tends to differ from other solid tumors with respect to p53 expression levels and mutation frequency. Thus, the following Specific Aims propose: (1) to examine the cell cycle regulatory pathways responsible for polyamine analog and inhibitor induction of G1 arrest in MALME-3M melanoma cells, focusing initially on the contribution of p53 and p21; (2) to identify the effectors responsible for polyamine analog induction of apoptosis in SK-MEL- 28 cells; (3) to investigate the polyamine-related initiating event(s) responsible for analog- and inhibitor-induced growth arrest and apoptosis; and (4) to confirm that specific analog- and inhibitor-induced effects that occur in vitro also occur in vivo. It is our belief that an understanding of cell cycle regulatory events by the two polyamine antagonists will contribute rationally to their deployment as anticancer agents and/or chemopreventive agents and at the same time, provide new insights into how the well-recognized polyamine requirement for cell growth interfaces with the complex pathways that control cell cycle progression and apoptosis.