Gemcitabine (2',2'-difluoro-2'-deoxycytidine), an antimetabolite that poisons topoisomerase I.

Abstract

The present results extend our recent finding that incorporation of 1-beta-D-arabinofuranosylcytosine into DNA can induce top1 cleavage complexes [P. Pourquier et al. Proc. Natl. Acad. Sci. USA, 97: 1885-1890, 2000]. The enhancement of camptothecin-induced top1 cleavage complexes may, at least in part, contribute to the synergistic or additive effects of gemcitabine in combination with topotecan and irinotecan in human breast or lung cancer cells.