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Rapid Transport of Novel Topo II Inhibitor into Cancer Cells

Rapid Transport of Novel Topo II Inhibitor into Cancer Cells

F14512, a Potent Antitumor Agent Targeting Topoisomerase II Vectored into Cancer Cells via the Polyamine Transport System
Jean-Marc Barret, Anna Kruczynski, Stéphane Vispé, et al.

Abstract
The polyamine transport system (PTS) is an energy-dependent machinery frequently overactivated in cancer cells with a high demand for polyamines. We have exploited the PTS to selectively deliver a polyamine-containing drug to cancer cells. F14512 combines an epipodophyllotoxin core-targeting topoisomerase II with a spermine moiety introduced as a cell delivery vector. The polyamine tail supports three complementary functions: (a) facilitate formulation of a watersoluble compound, (b) increase DNA binding to reinforce topoisomerase II inhibition, and (c) facilitate selective uptake by tumor cells via the PTS. F14512 is 73-fold more cytotoxic to Chinese hamster ovary cells compared with CHO-MG cells with a reduced PTS activity. A decreased sensitivity of L1210 leukemia cells to F14512 was observed in the presence of putrescine, spermidine, and spermine. In parallel, the spermine moiety considerably enhances the drug-DNA interaction, leading to a reinforced inhibition of topoisomerase II. The spermine tail of F14512 serves as a cell delivery vehicle as well as a DNA anchor, and this property translates at the cellular level into a distinct pharmacologic profile. Twenty-nine human solid or hematologic cell lines were used to characterize the high cytotoxic potential of F14512 (median IC50 of 0.18 Mmol/L). Finally, the potent antitumor activity of F14512 in vivo was evidenced with a MX1human breast tumor xenograft model, with partial and complete tumor regressions. This work supports the clinical development of F14512 as a novel targeted cytotoxic drug and sheds light on the concept of selective delivery of drugs to tumor cells expressing the PTS. [Cancer Res 2008;68(23):9845–53]

Article Source: Cancer Research Website

Human Topoisomerase II Alpha and Topo II Assay available from TopoGEN.

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