Zhu Jiuxiang, Song Xueqin, Lin Ho-Pi, Young Donn C, Yan Shunqi, Marquez Victor E, Chen Ching-Shih
Division of Medicinal Chemistry and Pharmacognosy, College of Pharmacy, The Ohio State University, 500 W. 12th Avenue, Columbus, OH 43210-1291, USA.
J Natl Cancer Inst. 2002 Dec 4;94(23):1745-57. doi: 10.1093/jnci/94.23.1745.
The cyclooxygenase-2 (COX-2) inhibitor celecoxib is thought to act as a chemopreventive agent by sensitizing cancer cells to apoptotic signals. Other COX-2 inhibitors, such as rofecoxib, are two orders of magnitude less potent than celecoxib at inducing apoptosis. The molecular structures of celecoxib and rofecoxib were used as starting points to examine the structural features that contribute to this discrepancy.
We used a systematic chemical approach to modify the structures of celecoxib and rofecoxib to produce a series of compounds that were tested for their effects on the viability of human prostate cancer PC-3 cells and their ability to induce apoptosis in these cells. Cell viability was measured by the trypan blue dye exclusion assay, and apoptosis was measured by an enzyme-linked immunosorbent assay that quantifies DNA cleavage and by western blot detection of poly(ADP-ribose) polymerase (PARP) cleavage. Western blotting was used to monitor the effects of the compounds on phosphorylation of the serine/threonine kinase Akt and extracellular signal-regulated kinase 2 (ERK2), two components of celecoxib-induced apoptosis signaling. Monte Carlo simulations were used to molecularly model the surface electrostatic potential and electron density of selected compounds. All statistical tests were two-sided.
The structural requirements for the induction of apoptosis in PC-3 cells were different from those for COX-2 inhibition. Structure-function analysis indicated that the induction of apoptosis by compounds derived from COX-2 inhibitors required a bulky terminal phenyl ring, a heterocyclic system with negative electrostatic potential, and a benzenesulfonamide or benzenecarboxamide moiety. These derivatives mediated apoptosis by facilitating the dephosphorylation of Akt and ERK2, irrespective of their COX-2 inhibitory activities.
A new class of compounds that induce apoptosis by targeting Akt and ERK2 signaling pathways in human prostate cancer cells can be synthesized by modifying existing COX-2 inhibitors.
环氧化酶-2（COX-2）抑制剂塞来昔布被认为通过使癌细胞对凋亡信号敏感而起到化学预防剂的作用。其他COX-2抑制剂，如罗非昔布，在诱导凋亡方面的效力比塞来昔布低两个数量级。以塞来昔布和罗非昔布的分子结构为出发点，研究导致这种差异的结构特征。
我们采用系统的化学方法修饰塞来昔布和罗非昔布的结构，制备了一系列化合物，并测试它们对人前列腺癌PC-3细胞活力的影响以及诱导这些细胞凋亡的能力。通过台盼蓝染料排斥试验测定细胞活力，通过定量DNA裂解的酶联免疫吸附测定和蛋白质印迹法检测聚（ADP-核糖）聚合酶（PARP）裂解来测定凋亡。采用蛋白质印迹法监测这些化合物对丝氨酸/苏氨酸激酶Akt和细胞外信号调节激酶2（ERK2）磷酸化的影响，这两者是塞来昔布诱导的凋亡信号传导的两个组成部分。使用蒙特卡罗模拟对选定化合物的表面静电势和电子密度进行分子建模。所有统计检验均为双侧检验。
PC-3细胞中诱导凋亡的结构要求与COX-2抑制的结构要求不同。结构-功能分析表明，源自COX-2抑制剂的化合物诱导凋亡需要一个庞大的末端苯环、一个具有负静电势的杂环系统以及一个苯磺酰胺或苯甲酰胺部分。这些衍生物通过促进Akt和ERK2的去磷酸化介导凋亡，而与它们的COX-2抑制活性无关。
通过修饰现有的COX-2抑制剂，可以合成一类通过靶向人前列腺癌细胞中的Akt和ERK2信号通路诱导凋亡的新化合物。
