Coxon F P, Benford H L, Russell R G, Rogers M J
Department of Medicine and Therapeutics, University of Aberdeen Medical School, Foresterhill, Aberdeen, AB25 2ZD, UK.
Mol Pharmacol. 1998 Oct;54(4):631-8.
The exact mechanisms of action of antiresorptive bisphosphonate drugs remain unclear, although they may inhibit bone resorption by mechanisms that can lead to osteoclast apoptosis. These drugs also cause apoptosis in J774 macrophages, probably as a consequence of inhibition of protein prenylation. However, the molecular pathways that lead to apoptosis are not known. In some cells, apoptosis induced by statins (other inhibitors of protein prenylation) is dependent on protein synthesis. The aim of this study was to further characterize the kinetics and biochemical features of bisphosphonate-induced apoptosis, including the dependence on protein synthesis. Alendronate-induced apoptosis in J774 cells occurred after approximately 16 hr of treatment, although shorter exposures to the drug followed by incubation in bisphosphonate-free medium also committed cells to apoptosis. The appearance of apoptotic cells was associated with the appearance of caspase-3-like activity. Apoptosis induced by bisphosphonate or mevastatin was found to be dependent on protein synthesis because cycloheximide inhibited chromatin condensation, DNA fragmentation and activation of caspase-3-like protease or proteases. Protein synthesis was required for events that lead to commitment to apoptosis but not for the execution phase because cycloheximide did not prevent apoptosis when added >/=15 hr after the start of alendronate treatment. Furthermore, staurosporine-induced caspase-3-like activity and apoptosis in J774 cells could not be prevented by cycloheximide. These observations demonstrate that activation of caspase-3-like proteases and inhibition of commitment to apoptosis by cycloheximide are common features of apoptotic cell death induced by inhibitors of protein prenylation such as bisphosphonates.
抗吸收双膦酸盐药物的确切作用机制仍不清楚，尽管它们可能通过导致破骨细胞凋亡的机制来抑制骨吸收。这些药物还会导致J774巨噬细胞凋亡，这可能是抑制蛋白质异戊二烯化的结果。然而，导致凋亡的分子途径尚不清楚。在某些细胞中，他汀类药物（蛋白质异戊二烯化的其他抑制剂）诱导的凋亡依赖于蛋白质合成。本研究的目的是进一步表征双膦酸盐诱导凋亡的动力学和生化特征，包括对蛋白质合成的依赖性。阿仑膦酸钠诱导J774细胞凋亡在处理约16小时后发生，尽管短时间接触该药物后在无双膦酸盐培养基中孵育也会使细胞发生凋亡。凋亡细胞的出现与类似半胱天冬酶-3的活性的出现相关。发现双膦酸盐或美伐他汀诱导的凋亡依赖于蛋白质合成，因为放线菌酮抑制染色质浓缩、DNA片段化以及类似半胱天冬酶-3的蛋白酶或多种蛋白酶的激活。蛋白质合成对于导致细胞走向凋亡的事件是必需的，但对于执行阶段不是必需的，因为在阿仑膦酸钠处理开始后≥15小时添加放线菌酮并不能阻止凋亡。此外，放线菌酮不能阻止星形孢菌素诱导的J774细胞中类似半胱天冬酶-3的活性和凋亡。这些观察结果表明，类似半胱天冬酶-3的蛋白酶的激活以及放线菌酮对凋亡的抑制是蛋白质异戊二烯化抑制剂（如双膦酸盐）诱导的凋亡细胞死亡的共同特征。
