The vascular targeting agent combretastatin-A4 and a novel cis-restricted β-lactam analogue, CA-432, induce apoptosis in human chronic myeloid leukemia cells and ex vivo patient samples including those displaying multidrug resistance

Lisa M. Greene, Seema M. Nathwani, Sandra A. Bright, Darren Fayne, Aisling Croke, Maria Gagliardi, Anthony M. McElligott, Lisa O'Connor, Miriam Carr, Niall O. Keely, Niamh M. O'Boyle, Peig Carroll, Balazs Sarkadi, Eibhlin Conneally, David G. Lloyd, Mark Lawler, Mary J. Meegan, Daniela M. Zisterer

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Abstract

Combretastatin-A4 (CA-4) is a natural derivative of the African willow tree Combretum caffrum. CA-4 is one of the most potent antimitotic components of natural origin, but it is, however, intrinsically unstable. A novel series of CA-4 analogs incorporating a 3,4-diaryl-2-azetidinone (β-lactam) ring were designed and synthesized with the objective to prevent cis-trans isomerization and improve the intrinsic stability without altering the biological activity of CA-4. Evaluation of selected β-lactam CA-4 analogs demonstrated potent antitubulin, antiproliferative, and antimitotic effects in human leukemia cells. A lead β-lactam analog, CA-432, displayed comparable antiproliferative activities with CA-4. CA-432 induced rapid apoptosis in HL-60 acute myeloid leukemia cells, which was accompanied by depolymerization of the microtubular network, poly(ADP-ribose) polymerase cleavage, caspase-3 activation, and Bcl-2 cleavage. A prolonged G2M cell cycle arrest accompanied by a sustained phosphorylation of mitotic spindle checkpoint protein, BubR1, and the antiapoptotic proteins Bcl-2 and Bcl-xL preceded apoptotic events in K562 chronic myeloid leukemia (CML) cells. Molecular docking studies in conjunction with comprehensive cell line data rule out CA-4 and β-lactam derivatives as P-glycoprotein substrates. Furthermore, both CA-4 and CA-432 induced significantly more apoptosis compared with imatinib mesylate in ex vivo samples from patients with CML, including those positive for the T315I mutation displaying resistance to imatinib mesylate and dasatinib. In summary, synthetic intrinsically stable analogs of CA-4 that display significant clinical potential as antileukemic agents have been designed and synthesized.

Original languageEnglish
Pages (from-to)302-313
Number of pages12
JournalJournal of Pharmacology and Experimental Therapeutics
Volume335
Issue number2
DOIs
Publication statusPublished - Nov 1 2010

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ASJC Scopus subject areas

  • Molecular Medicine
  • Pharmacology

Cite this

Greene, L. M., Nathwani, S. M., Bright, S. A., Fayne, D., Croke, A., Gagliardi, M., McElligott, A. M., O'Connor, L., Carr, M., Keely, N. O., O'Boyle, N. M., Carroll, P., Sarkadi, B., Conneally, E., Lloyd, D. G., Lawler, M., Meegan, M. J., & Zisterer, D. M. (2010). The vascular targeting agent combretastatin-A4 and a novel cis-restricted β-lactam analogue, CA-432, induce apoptosis in human chronic myeloid leukemia cells and ex vivo patient samples including those displaying multidrug resistance. Journal of Pharmacology and Experimental Therapeutics, 335(2), 302-313. https://doi.org/10.1124/jpet.110.170415