Asakura T, Takahashi N, Takada K, Inoue T, Ohkawa K
Department of Biochemistry (I), Jikei University School of Medicine, Minato-ku, Tokyo, Japan.
Anticancer Drugs. 1997 Feb;8(2):199-203. doi: 10.1097/00001813-199702000-00011.
A recent study has suggested that degraded adducts smaller than 2 kDa in molecular weight of bovine serum albumin (BSA)-conjugated doxorubicin (DXR) (BSA-DXR) might exhibit cytotoxicity against multidrug resistant (MDR) cells. To investigate this notion further, intracellular accumulation and cytotoxicity of DXR coupled to several small peptides, such as glycylglycine (diGly), glycylglycylglycine (triGly), reduced glutathione (GSH) and oxidized glutathione (GSSG), were investigated using DXR-sensitive (AH66P) and DXR-resistant (AH66DR) rat hepatoma cell lines. Against both AH66P and AH66DR cells, diGly-conjugated DXR (diGly-DXR) and triGly-conjugated DXR (triGly-DXR) demonstrated the same cytotoxic activity as DXR, and the accumulation of both conjugates in the two cell lines was almost similar to that of DXR. After treatment of AH66DR cells with 5 microM verapamil [an inhibitor of P-glycoprotein (Pgp)], the intracellular levels of diGly-DXR and triGly-DXR were markedly increased and consequent cytotoxicity was improved. On the other hand, GSH-conjugated DXR (GSH-DXR) showed 9- and 7.5-fold more cytotoxic activity than BSA-DXR against AH66P and AH66DR cells, respectively. GSH-DXR accumulated rapidly in AH66DR cells, probably by the same mechanism as in AH66P cells, because the treatment of AH66DR cells with verapamil did not cause a significant increase in the intracellular drug level as compared with that in cells treated without verapamil. The levels of cytotoxicity and accumulation of GSSG-DXR were the same as those of BSA-DXR for both cell lines. These results indicate that GSH-DXR exerts potent cytotoxicity against both cell lines among the peptide DXR conjugates examined because of the rapid uptake and high accumulation of GSH-DXR similar to that of DXR without efflux.
最近的一项研究表明，与牛血清白蛋白（BSA）偶联的阿霉素（DXR）（BSA-DXR）分子量小于2 kDa的降解加合物可能对多药耐药（MDR）细胞具有细胞毒性。为了进一步研究这一观点，使用对DXR敏感的（AH66P）和对DXR耐药的（AH66DR）大鼠肝癌细胞系，研究了与几种小肽偶联的DXR的细胞内积累和细胞毒性，这些小肽包括甘氨酰甘氨酸（二肽甘氨酸）、甘氨酰甘氨酰甘氨酸（三肽甘氨酸）、还原型谷胱甘肽（GSH）和氧化型谷胱甘肽（GSSG）。对于AH66P和AH66DR细胞，二肽甘氨酸偶联的DXR（二肽甘氨酸-DXR）和三肽甘氨酸偶联的DXR（三肽甘氨酸-DXR）表现出与DXR相同的细胞毒性活性，并且这两种偶联物在两种细胞系中的积累几乎与DXR相似。用5 microM维拉帕米[一种P-糖蛋白（Pgp）抑制剂]处理AH66DR细胞后，二肽甘氨酸-DXR和三肽甘氨酸-DXR的细胞内水平显著增加，随后细胞毒性得到改善。另一方面，GSH偶联的DXR（GSH-DXR）对AH66P和AH66DR细胞的细胞毒性活性分别比BSA-DXR高9倍和7.5倍。GSH-DXR在AH66DR细胞中迅速积累，可能与在AH66P细胞中的机制相同，因为与未用维拉帕米处理的细胞相比，用维拉帕米处理AH66DR细胞并未导致细胞内药物水平显著增加。对于两种细胞系，GSSG-DXR的细胞毒性和积累水平与BSA-DXR相同。这些结果表明，在所研究的肽-DXR偶联物中，GSH-DXR对两种细胞系均具有强大的细胞毒性，这是因为GSH-DXR的快速摄取和高积累类似于DXR且无外排。
