Consoli U, Priebe W, Ling Y H, Mahadevia R, Griffin M, Zhao S, Perez-Soler R, Andreeff M
Department of Hematology, University of Texas M.D. Anderson Cancer Center, Houston, USA.
Blood. 1996 Jul 15;88(2):633-44.
A major factor in limiting the efficacy of anthracyclines is overexpression of the MDR1-encoded p-glycoprotein (p-gp). A new analogue less affected by p-gp is annamycin (ANN), an anthracycline antibiotic with high affinity for lipid membranes and significantly more activity than doxorubicin (DOX). We investigated whether ANN was affected by p-gp-mediated multidrug resistance (MDR) by comparing the cellular accumulation and retention of ANN, idarubicin (IDR), and DOX in the p-gp-negative human leukemia cell lines (HL-60S) and its DOX-selected p-gp-positive subline (HL-60/DOX) with and without verapamil (VER). As expected, HL-60/DOX cells showed lower DOX uptake than HL-60S cells; coincubation with VER (10 mmol/L) increased uptake 2.6-fold restoring it to 100% of uptake in HL-60S cells. IDR uptake increased 1.5-fold in the presence of VER, but ANN was not affected. Coincubation with VER increased DOX retention in HL-60/DOX cells 2.8-fold and IDR retention 1.4-fold; unchanged ANN retention indicated that ANN may overcome p-gp. In the cytotoxicity assay to correlate intracellular anthracycline content with antitumor activity, we found ANN to be less potent than DOX and IDR In sensitive cells, ID 50 being the drug concentration that inhibits cell growth by 50% but its resistance index (RI; ID50 resistant cells divided by ID50 sensitive cells) was lower than that of IDR and DOX (2.6 v 40 and 117.5). Coincubation in the presence of VER resulted in 4.5-fold and 2-fold RI decreases of DOX and IDR, respectively, whereas ANN did not change, further confirming ANN's ability to circumvent p-gp-mediated MDR. Confocal microscopy studies of IDR, ANN, and DOX showed higher intracellular drug compartmentalization for DOX in HL-60/DOX cells incubated in the presence of VER. This study provided evidence that, unlike DOX and IDR, ANN is not affected by p-gp-mediated MDR.
限制蒽环类药物疗效的一个主要因素是MDR1编码的P-糖蛋白（P-gp）的过表达。一种受P-gp影响较小的新类似物是安那霉素（ANN），它是一种对脂质膜具有高亲和力且活性明显高于阿霉素（DOX）的蒽环类抗生素。我们通过比较ANN、伊达比星（IDR）和DOX在P-gp阴性人白血病细胞系（HL-60S）及其经DOX筛选的P-gp阳性亚系（HL-60/DOX）中在有和没有维拉帕米（VER）的情况下的细胞摄取和滞留情况，研究了ANN是否受P-gp介导的多药耐药（MDR）影响。正如预期的那样，HL-60/DOX细胞的DOX摄取低于HL-60S细胞；与VER（10 mmol/L）共同孵育使摄取增加2.6倍，恢复到HL-60S细胞摄取的100%。在VER存在的情况下，IDR摄取增加1.5倍，但ANN不受影响。与VER共同孵育使HL-60/DOX细胞中的DOX滞留增加2.8倍，IDR滞留增加1.4倍；ANN滞留不变表明ANN可能克服P-gp。在细胞毒性试验中，为了将细胞内蒽环类药物含量与抗肿瘤活性相关联，我们发现ANN在敏感细胞中的效力低于DOX和IDR，半数抑制浓度（ID50）是抑制细胞生长50%的药物浓度，但其耐药指数（RI；耐药细胞的ID50除以敏感细胞的ID50）低于IDR和DOX（分别为2.6对40和117.5）。在VER存在的情况下共同孵育分别导致DOX和IDR的RI降低4.5倍和2倍，而ANN没有变化，进一步证实了ANN规避P-gp介导的MDR的能力。对IDR、ANN和DOX的共聚焦显微镜研究显示，在VER存在下孵育的HL-60/DOX细胞中，DOX的细胞内药物分隔更高。这项研究提供了证据，表明与DOX和IDR不同，ANN不受P-gp介导的MDR影响。
