Binding of manumycin A inhibits IkappaB kinase beta activity.
IkappaB kinase (IKK) catalytic subunits play a key role in cytokinemediated nuclear factor (NF)-kappaB signaling, and a loss of NF-kappaB function appears to inhibit inflammation and oncogenesis. Manumycin A is a potent and selective farnesyltransferase inhibitor with antitumor activity. We found that manumycin A caused a rapid and potent inhibition of IKK activity induced by tumor necrosis factor alpha in a number of cell types. Most unexpectedly, other classes of farnesyltransferase inhibitors had no inhibitory effect. To identify the molecular mechanisms of manumycin A action, cultured human HepG2 hepatoma cells were transiently transfected with various IKKalpha and IKKbeta constructs, and a striking difference in manumycin A sensitivity was observed. Furthermore, cells expressing wild-type IKKbeta and IKKbeta mutated in the activation loop at Cys-179 exhibited covalent homotypic dimerization of IKKbeta in response to manumycin A, whereas substitution of Cys-662 and -716 conferred protection against dimer formation. Direct inhibition of IKK activity and formation of stable IKKbeta dimers were observed in the presence of manumycin A that could be blocked by dithiothreitol. IKK interaction with the adaptor protein IKKgamma/NEMO was disrupted in manumycin A-treated cells. Most importantly, administration of manumycin A to mice xenografted with murine B16F10 tumors caused potent IKK-suppressive effects. Thus, manumycin A with its epoxyquinoid moieties plays an important regulatory function in IKK signaling through pathways distinct from its role as a protein farnesylation inhibitor.
Bernier
Michel
M
Diabetes Section, Bioanalytical Chemistry and Drug Discovery Section, Laboratory of Clinical Investigation, and Laboratory of Experimental Gerontology, NIA, National Institutes of Health, Baltimore, Maryland 21224, USA. Bernierm@grc.nia.nih.gov
Kwon
Yong-Kook
YK
Pandey
Sanjay K
SK
Zhu
Tie-Nian
TN
Zhao
Rui-Jing
RJ
Maciuk
Alexandre
A
He
Hua-Jun
HJ
Decabo
Rafael
R
Kole
Sutapa
S
D019943:Amino Acid Substitution; D000818:Animals; D045744:Cell Line, Tumor; D019281:Dimerization; D006801:Humans; D051550:I-kappa B Kinase / Q000037:antagonists & inhibitors* / Q000235:genetics; D051379:Mice; D009374:Neoplasms, Experimental / Q000188:drug therapy; D011090:Polyenes / Q000494:pharmacology* / Q000627:therapeutic use; D053284:Polyunsaturated Alkamides; D011485:Protein Binding; D014162:Transfection; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology
D011090:Polyenes; D053284:Polyunsaturated Alkamides; D014409:Tumor Necrosis Factor-alpha; D051550:I-kappa B Kinase; C054474:manumycin