The antitumor anthracycline doxorubicin induces a dose-related cardiotoxicity that correlates with the myocardial levels of its secondary alcohol metabolite doxorubicinol. Combining doxorubicin with taxanes such as paclitaxel or docetaxel may aggravate cardiotoxicity, presumably because the taxanes cause an allosteric-like stimulation of cytoplasmic aldehyde reductases that convert doxorubicin to doxorubicinol in the heart. A less severe aggravation of cardiotoxicity was observed on combining taxanes with epirubicin, a closely related analog of doxorubicin; therefore, we characterized whether the cardiac tolerability of epirubicin-taxane therapies could be due to a defective taxane stimulation of the conversion of epirubicin to its secondary alcohol metabolite epirubicinol. Comparisons between doxorubicin and epirubicin in isolated human heart cytosol showed that epirubicin exhibited a lower V max/ K m value for reaction with aldehyde reductases and a defective stimulation of epirubicinol formation by paclitaxel or docetaxel. A similar pattern occurred in the soluble fraction of human myocardial strips incubated in plasma with anthracyclines and paclitaxel or docetaxel, formulated in their clinical vehicles Cremophor EL or polysorbate 80. Doxorubicin, but not epirubicin, was also able to generate reactive oxygen species in the membrane fraction of myocardial strips; however, the levels of doxorubicin-derived reactive oxygen species were not further augmented by paclitaxel. These results support the notion that taxanes might aggravate the cardiotoxicity of doxorubicin through a specific stimulation of doxorubicinol formation. The failure of paclitaxel or docetaxel to stimulate epirubicinol formation therefore uncovers an important determinant of the improved cardiac tolerability of epirubicin-taxane combinations.
抗肿瘤
蒽环类
阿霉素会引起剂量相关的心脏毒性,该毒性与其二级醇代谢物
阿霉素的心肌
水平相关。
阿霉素与
紫杉醇或多西
紫杉醇等
紫杉烷类药物联合使用可能会加重心脏毒性,可能是因为
紫杉烷类药物会引起细胞质醛还原酶的变构样刺激,从而在心脏中将
阿霉素转化为
阿霉素。将
紫杉烷类药物与
表柔比星(
阿霉素的一种密切相关的类似物)联合使用时,观察到心脏毒性的加重程度较轻。因此,我们表征了
表阿霉素-
紫杉烷疗法的心脏耐受性是否可能是由于
紫杉烷刺激
表阿霉素转化为其二级醇代谢物
表阿霉素的缺陷所致。在分离的人心脏细胞质中对
阿霉素和
表阿霉素进行比较表明,
表阿霉素与醛还原酶反应时表现出较低的 V max/K m 值,并且
紫杉醇或
多西他赛对
表阿霉素形成的刺激有缺陷。在血浆中与
蒽环类药物和
紫杉醇或多西
紫杉醇一起孵育的人心肌条的可溶部分也出现了类似的模式,这些心肌条是在其临床载体 Cremophor EL 或
多西他赛 80 中配制的。
多柔比星(但不是
表柔比星)也能够在膜中产生活性氧。心肌条的分数;然而,
紫杉醇并没有进一步提高
阿霉素衍生的活性氧的
水平。这些结果支持
紫杉烷类可能通过特异性刺激
阿霉素形成而加重
阿霉素的心脏毒性的观点。因此,
紫杉醇或多西
紫杉醇不能刺激
表柔比星醇形成,揭示了
表柔比星-
紫杉烷组合改善心脏耐受性的重要决定因素。