PMID: 18204782Jan 22, 2008Paper

Novel tubulin-polymerization inhibitor derived from thalidomide directly induces apoptosis in human multiple myeloma cells: possible anti-myeloma mechanism of thalidomide

International Journal of Molecular Medicine
Toyotaka IguchiMasahiro Kizaki

Abstract

To ascertain the exact anti-myeloma mechanism of thalidomide in vivo, we performed structural development studies of thalidomide, and obtained various analogues with specific molecular properties. Among these derivatives, we found that a new thalidomide analogue, 2-(2,6-diisopropylphenyl)-5-hydroxy-1H-isoindole-1,3-dione (5HPP-33) had the most potent anti-myeloma effect and tubulin-polymerization-inhibiting activity. 5HPP-33 directly inhibited the growth and survival of various myeloma cell lines (RPMI8226, U266, and IM9) in a dose-dependent manner with IC50 of 1-10 microM. In contrast, thalidomide itself did not inhibit cellular growth of RPMI8226 cells. Cultivation with 10 microM 5HPP-33 induced G2/M phase cell cycle arrest, followed by apoptosis of myeloma cells. Treatment with 5HPP-33 induced caspase-3 activity and PARP cleavage. A tubulin polymerization assay using microtubule protein from porcine brain revealed that 5HPP-33 showed potent tubulin-polymerization-inhibiting activity with IC50 of 8.1 microM, comparable to that of the known tubulin-polymerization inhibitor, rhizoxin. Moreover, its activity was more potent than that of a known thalidomide metabolite, 5-hydroxythalidomide. Notably, the structural requirement for...Continue Reading

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Apoptosis

Apoptosis is a specific process that leads to programmed cell death through the activation of an evolutionary conserved intracellular pathway leading to pathognomic cellular changes distinct from cellular necrosis