Nagata T, Higashigawa M, Shimono Y, Cao D C, Yan Mao X, M'soka T, Inamochi H, Hori H, Kawasaki H, Sakurai M
Dept. of Pediatrics, Mie University School of Medicine, Tsu-city, Japan.
J Exp Clin Cancer Res. 1998 Dec;17(4):435-42.
It has been reported that aclarubicin inhibits etoposide (VP-16) induced cytotoxicity in human lung cancer cell lines (1, 2). However, it still remains unclear how aclarubicin (ACR) inhibits etoposide-induced cytotoxicity. We report here that the combination of ACR and VP-16 showed antagonistic cytotoxic effect in P388 murine leukemic cells. DNA unwinding assay showed that 1000 ng/ml ACR significantly reduced VP-16 induced early DNA double strand(ds) breaks compared to that of VP-16 alone at a concentration of 10 microM. However, ACR did not inhibit VP-16 induced early DNA double strand breaks at a concentration of 100 ng/ml, a clinically achievable concentration. Furthermore, DNA repair occurred within two hours after removing VP-16 even if ACR was co-cultured at concentrations of 100 and 1000 ng/ml. DNA agarose gel electrophoresis and detection of sub-G1 fraction by flowcytometer showed that 100 ng/ml of ACR inhibited VP-16 induced DNA ladder formation and formation of sub-G1 fraction. Radioactive precursor incorporation studies showed that VP-16 inhibited DNA synthesis rather than RNA synthesis. On the other hand, ACR selectively inhibited RNA synthesis at a concentration of 100 ng/ml. The VP-16 induced increment of [3H]-L-leucine uptake was canceled by addition of 100 ng/ml of ACR. These data suggest that ACR inhibited VP-16 induced apoptosis by the inhibition of RNA synthesis along with protein synthesis, but not early DNA double strand breaks and DNA repair at a concentration of 100 ng/ml in P388 murine leukemic cells.
据报道，阿柔比星可抑制依托泊苷（VP-16）对人肺癌细胞系的细胞毒性作用（1,2）。然而，阿柔比星（ACR）如何抑制依托泊苷诱导的细胞毒性作用仍不清楚。我们在此报告，ACR与VP-16联合使用对P388小鼠白血病细胞具有拮抗细胞毒性作用。DNA解旋试验表明，与单独使用10μM浓度的VP-16相比，1000 ng/ml的ACR可显著减少VP-16诱导的早期DNA双链（ds）断裂。然而，在100 ng/ml这一临床可达到的浓度下，ACR并未抑制VP-16诱导的早期DNA双链断裂。此外，即使在100和1000 ng/ml浓度下将ACR共同培养，去除VP-16后两小时内仍会发生DNA修复。DNA琼脂糖凝胶电泳和流式细胞仪检测亚G1期细胞比例结果显示，100 ng/ml的ACR可抑制VP-16诱导的DNA梯状条带形成和亚G1期细胞比例的形成。放射性前体掺入研究表明，VP-16抑制DNA合成而非RNA合成。另一方面，ACR在100 ng/ml浓度下选择性抑制RNA合成。添加100 ng/ml的ACR可消除VP-16诱导的[3H]-L-亮氨酸摄取增加。这些数据表明，在P388小鼠白血病细胞中，100 ng/ml浓度的ACR通过抑制RNA合成以及蛋白质合成来抑制VP-16诱导的细胞凋亡，而非早期DNA双链断裂和DNA修复。
