Agents that reverse multidrug resistance, tamoxifen, verapamil, and cyclosporin A, block glycosphingolipid metabolism by inhibiting ceramide glycosylation in human cancer cells.
J Biol Chem
; 272(3): 1682-7, 1997 Jan 17.
Article
em En
| MEDLINE
| ID: mdl-8999846
ABSTRACT
We have previously shown that multidrug-resistant cancer cells display elevated levels of glucosylceramide (Lavie, Y., Cao, H., Bursten, S. L., Giuliano, A. E., and Cabot, M. C. (1996) J. Biol. Chem. 271, 19530-19536). In this study we used the multidrug-resistant human breast cancer cell line MCF-7-Adriamycin-resistant (AdrR), which exhibits marked accumulation of glucosylceramide compared with the parental MCF-7 wild type (drug-sensitive) cell line, to define the relationship between glycolipids and multidrug resistance (MDR). Herein it is shown that clinically relevant concentrations of tamoxifen, verapamil, and cyclosporin A, all circumventors of MDR, markedly decrease glucosylceramide levels in MCF-7-AdrR cells (IC50 values, 1. 0, 0.8, and 2.3 microM, respectively). In intact cells, tamoxifen inhibited glycosphingolipid synthesis at the step of ceramide glycosylation. In cell-free assays for glucosylceramide synthase, tamoxifen (110 molar ratio with ceramide) inhibited glucosylceramide formation by nearly 50%. In cell cultures, inhibition of glucosylceramide synthesis by tamoxifen is correlated with its ability to sensitize MCF-7-AdrR cells to Adriamycin toxicity. Moreover, treatment of cells with 1-phenyl-2-palmitoylamino-3-morpholino-1-propanol, an inhibitor of glucosylceramide synthesis, likewise sensitized MCF-7-AdrR cells to Adriamycin. It is concluded that high cellular levels of glucosylceramide are correlated with MDR, and that glycolipids are a target for the action of MDR-reversing agents such as tamoxifen. The data entertain the notion that drug resistance phenomena are aligned with cell capacity to metabolize ceramide.
Buscar no Google
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Tamoxifeno
/
Glicoesfingolipídeos
/
Verapamil
/
Ceramidas
/
Ciclosporina
Limite:
Humans
Idioma:
En
Revista:
J Biol Chem
Ano de publicação:
1997
Tipo de documento:
Article
País de afiliação:
Estados Unidos