Format

Send to

Choose Destination
Cancer Chemother Pharmacol. 1999;44(2):131-7.

Structure-activity profiles of eleutherobin analogs and their cross-resistance in Taxol-resistant cell lines.

Author information

1
Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, NY 10461, USA.

Abstract

PURPOSE:

Eleutherobin, a natural product, is an antimitotic agent that promotes the polymerization of stable microtubules. Although its mechanism of action is similar to that of Taxol, its structure is distinct. A structure-activity profile of synthetic eleutherobin derivatives that have modifications at C3, C8 and C15 was undertaken to define the structural requirements for microtubule stabilization and cross-resistance in Taxol-resistant cell lines.

METHODS:

The biological activity of five eleutherobin analogs was assessed using three techniques: (1) cytotoxicity and drug-resistance in three paired Taxol-sensitive and -resistant cell lines; (2) polymerization of microtubule protein in vitro in the absence of GTP and (3) induction of microtubule bundle formation in NIH3T3 cells.

RESULTS:

Eleutherobin had an IC50 value comparable to that of Taxol, whereas neoeleutherobin, which has a carbohydrate domain that is enantiomeric with that of the parent compound, was less cytotoxic and had 69% of the maximum microtubule polymerization ability of eleutherobin. Both of these compounds exhibited cross-resistance in MDRI-expressing cell lines. Removal or replacement of the C15 sugar moiety resulted in reduced microtubule polymerization and cytotoxicity compared to eleutherobin and loss of cross-resistance in the cell lines SKVLB and J7-T3-1.6, both of which express high levels of P-glycoprotein. By contrast, removal of the urocanic acid group at C8 resulted in virtually complete abrogation of biological activity. The compound lost its ability to polymerize microtubules, and its cytotoxicity was reduced by a minimum of 2000-fold in lung carcinoma A549 cells.

CONCLUSIONS:

Removal or modification of the sugar moiety alters the cytotoxic potency of eleutherobin and its pattern of cross-resistance in Taxol-resistant cells, although such compounds retain a small percentage of the microtubule-stabilizing activity of eleutherobin. The N(1)-methylurocanic acid moiety of eleutherobin, or perhaps some other substituent at the C8 position, is essential for Taxol-like activity. These findings will be important for the future design and the synthesis of new and more potent eleutherobin derivatives.

PMID:
10412947
DOI:
10.1007/s002800050957
[Indexed for MEDLINE]

Supplemental Content

Full text links

Icon for Springer
Loading ...
Support Center