Priebe W, Van N T, Burke T G, Perez-Soler R
Department of Medical Oncology, University of Texas MD Anderson Cancer Center, Houston 77030.
Anticancer Drugs. 1993 Feb;4(1):37-48. doi: 10.1097/00001813-199302000-00005.
Hydroxyrubicin, a synthetic doxorubicin analog in which the basic amino group at C-3' is replaced by a hydroxyl group, was used as a prototype compound to study the effects of basicity of the sugar moiety on the toxicity and antitumor activity of anthracycline antibiotics. Compared with doxorubicin, hydroxyrubicin showed similar or superior in vitro cytotoxicity against P388, L1210, and M5076 cells, as determined by an MTT assay, and against 8226 and CEM cells, as determined by a growth inhibition assay. Hydroxyrubicin was 5 and 13 times more effective than doxorubicin in inhibiting the growth of multidrug-resistant CEM (CEMvbl) and 8226 (8226R) cells, respectively. Hydroxyrubicin was not cross-resistant with doxorubicin in a cytotoxicity assay against KB 3-1 and KB V1 cells (resistance index 1.1 for hydroxyrubicin versus > 15.6 for doxorubicin). Cellular uptake and retention of hydroxyrubicin were studied by flow cytometry in parent and multidrug-resistant 8226 cells, and compared with those of doxorubicin. In 8226 sensitive cells, 2 h uptake and retention of doxorubicin were similar or higher than those of hydroxyrubicin. In 8226R cells, uptake and retention of hydroxyrubicin were about 3-fold higher than those of doxorubicin. In mice, the acute LD50 of hydroxyrubicin was about 3-fold higher than that of doxorubicin (79.1 versus 25.7 mg/kg). At equitoxic doses, hydroxyrubicin was as myelosuppressive as doxorubicin but less cardiotoxic, as assessed by the Bertazzoli test. In contrast to doxorubicin, hydroxyrubicin, due to the lack of basic amine function, showed no selective interaction with negatively-charged cardiolipin (CL). The observed decrease of affinity to CL might be responsible for the reduced cardiotoxicity of hydroxyrubicin. In in vivo antitumor activity studies, hydroxyrubicin at the optimal dose (37.5 mg/kg, i.p., on day 1) had significant activity against intraperitoneal P388 leukemia resistant to doxorubicin, whereas doxorubicin (10 mg/kg, i.p., on day 1) was inactive (%T/C 163-200 versus 118-120). These studies indicate that: (i) the amino group at position 3' is not essential for doxorubicin to exert its biological activity, (ii) removal of the basic center (deamination at the C-3') results in an increased cellular uptake and retention, (iii) the increased cellular uptake and retention of hydroxyrubicin in multidrug-resistant cells correlate with a partial or total lack of cross-resistance of this analog with the parent compound, doxorubicin, and (iv) deamination at position 3' confers a reduced cardiotoxicity and diminished affinity for CL.
羟基柔红霉素是一种合成的柔红霉素类似物，其中C-3'位的碱性氨基被羟基取代，它被用作原型化合物来研究糖部分的碱性对蒽环类抗生素毒性和抗肿瘤活性的影响。通过MTT法测定，与柔红霉素相比，羟基柔红霉素对P388、L1210和M5076细胞显示出相似或更高的体外细胞毒性；通过生长抑制试验测定，对8226和CEM细胞也有相似结果。羟基柔红霉素抑制多药耐药CEM（CEMvbl）和8226（8226R）细胞生长的效果分别比柔红霉素高5倍和13倍。在针对KB 3-1和KB V1细胞的细胞毒性试验中，羟基柔红霉素与柔红霉素不存在交叉耐药性（羟基柔红霉素的耐药指数为1.1，而柔红霉素大于15.6）。通过流式细胞术研究了羟基柔红霉素在亲本和多药耐药8226细胞中的细胞摄取和滞留情况，并与柔红霉素进行了比较。在8226敏感细胞中，柔红霉素2小时的摄取和滞留与羟基柔红霉素相似或更高。在8226R细胞中，羟基柔红霉素的摄取和滞留比柔红霉素高约3倍。在小鼠中，羟基柔红霉素的急性半数致死量（LD50）比柔红霉素高约3倍（79.1对25.7毫克/千克）。在等毒性剂量下，通过Bertazzoli试验评估，羟基柔红霉素与柔红霉素的骨髓抑制作用相当，但心脏毒性较小。与柔红霉素不同，由于缺乏碱性胺功能，羟基柔红霉素与带负电荷的心磷脂（CL）没有选择性相互作用。观察到的对CL亲和力的降低可能是羟基柔红霉素心脏毒性降低的原因。在体内抗肿瘤活性研究中，羟基柔红霉素在最佳剂量（第1天腹腔注射37.5毫克/千克）下对柔红霉素耐药的腹腔P388白血病具有显著活性，而柔红霉素（第1天腹腔注射10毫克/千克）则无活性（%T/C为163 - 200对118 - 120）。这些研究表明：（i）3'位的氨基对于柔红霉素发挥其生物活性不是必需的；（ii）去除碱性中心（C-3'位脱氨基）导致细胞摄取和滞留增加；（iii）羟基柔红霉素在多药耐药细胞中增加的细胞摄取和滞留与该类似物与母体化合物柔红霉素部分或完全缺乏交叉耐药性相关；（iv）3'位脱氨基使心脏毒性降低且对CL的亲和力减弱。
