Novel suicide ligands of tubulin arrest cancer cells in S-phase.
It is presently accepted that the mechanism of action for all anti-tumor tubulin ligands involves the perturbation of microtubule dynamics during the G2/M phase of cell division and subsequent entry into apoptosis [1]. In this report, we challenge the established dogma by describing a unique mechanism of action caused by a novel series of tubulin ligands, halogenated derivatives of acetamido benzoyl ethyl ester. We have developed a suicide ligand for tubulin, which covalently attaches to the target and shows potent cancericidal activity in tissue culture assays and in animal tumor models. These compounds target early S-phase at the G1/S transition rather than the G2/M phase and mitotic arrest. Bcl-2 phosphorylation, a marker of mitotic microtubule inhibition by other tubulin ligands was dramatically altered, phosphorylation was rapid and biphasic rather than a slow linear event. The halogenated ethyl ester series of derivatives thus constitute a unique set of tubulin ligands which induce a novel mechanism of apoptosis.
Davis
A
A
Cytoskeleton Inc., Denver, CO 80206, USA.
Jiang
J D
JD
Middleton
K M
KM
Wang
Y
Y
Weisz
I
I
Ling
Y H
YH
Bekesi
J G
JG
D000970:Antineoplastic Agents / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects*; D006801:Humans; D008024:Ligands; D016196:S Phase; D014404:Tubulin / Q000378:metabolism*; D014407:Tumor Cells, Cultured
D000970:Antineoplastic Agents; D008024:Ligands; D014404:Tubulin