1.Biological evaluation of KRIBB3 analogs as a microtubule polymerization inhibitor.
Lee S1, Kim JN, Lee HK, Yoon KS, Shin KD, Kwon BM, Han DC. Bioorg Med Chem Lett. 2011 Feb 1;21(3):977-9. doi: 10.1016/j.bmcl.2010.12.044. Epub 2010 Dec 13.
A series of KRIBB3 analogs were synthesized by modifying substituents at aryl moieties of KRIBB3 for examining structure-activity relationships, and their inhibitory activities on microtubule polymerization were evaluated. The presence of free phenolic hydrogens in aryl moieties of KRIBB3 analogs plays an important role in inhibition of microtubule polymerization.
2.KRIBB3, a novel microtubule inhibitor, induces mitotic arrest and apoptosis in human cancer cells.
Shin KD1, Yoon YJ, Kang YR, Son KH, Kim HM, Kwon BM, Han DC. Biochem Pharmacol. 2008 Jan 15;75(2):383-94. Epub 2007 Aug 30.
KRIBB3 (5-(5-ethyl-2-hydroxy-4-methoxyphenyl)-4-(4-methoxyphenyl) isoxazole) inhibited cancer cell growth in vitro and in vivo. Flow cytometry studies showed that KRIBB3 caused cell cycle arrest at the G(2)/M phase and subsequent apoptosis. This was confirmed as accumulation of Cyclin B1 and cleavage of poly(ADP-ribose) polymerase (PARP) were detected. While transient inhibition by KRIBB3 led to reversible mitotic arrest, prolonged exposure to KRIBB3-induced apoptosis. Co-immunoprecipitation experiments showed that KRIBB3 initially induced association of inhibitory Mad2 with p55CDC (mammalian homologue of CDC20), an activator of APC/C (anaphase-promoting complex/cyclosome), suggesting that the mitotic spindle checkpoint was activated by KRIBB3. However, the level of this inhibitory complex of Mad2 with p55CDC was gradually decreased 24 h after KRIBB3 treatment, and was hardly detectable after 48 h, indicating some slipping of the mitotic checkpoint.
3.Blocking tumor cell migration and invasion with biphenyl isoxazole derivative KRIBB3, a synthetic molecule that inhibits Hsp27 phosphorylation.
Shin KD1, Lee MY, Shin DS, Lee S, Son KH, Koh S, Paik YK, Kwon BM, Han DC. J Biol Chem. 2005 Dec 16;280(50):41439-48. Epub 2005 Oct 18.
Cell migration is a prerequisite for cancer invasion and metastasis, suggesting cell motility as a potential therapeutic target for cancer treatment. A synthetic library was screened to identify inhibitors of tumor cell migration. From this, we discovered that CAC-1098 (aurintricarboxylic acid) and CBI-0997 (5-(2,4-dimethoxy-5-ethylphenyl)-4-(4-bromophenyl) isoxazole) inhibited migration of MDA-MB-231 cells with IC50 = 5 and 50 nM, respectively. We synthesized KRIBB3 (5-(5-ethyl-2-hydroxy-4-methoxyphenyl)-4-(4-methoxyphenyl) isoxazole) by replacing the bromide group of CBI-0997 with a methoxyl group. Like CBI-0997, KRIBB3 has anti-migratory and anti-invasive activities in MDA-MB-231 cells. Because KRIBB3 has a better drug-like structure, we focused our effort on further understanding its anti-migratory mechanism. Biotinyl-KRIBB3 was synthesized as an affinity probe for identification of KRIBB3-binding proteins. Using affinity chromatography, we identified Hsp27 as a target protein of KRIBB3 in vitro.