RT info:eu-repo/semantics/article T1 Inhibition of IκB kinase by a new class of retinoid-related anticancer agents that induce apoptosis A1 Bayón Prieto, Yolanda A1 Ortiz, Maria A. A1 Lopez Hernandez, Francisco J. A1 Gao, Feng A1 Karin, Michael A1 Pfahl, Magnus A1 Piedrafita, F. Javier K1 Kinase K1 Quinasa K1 Retinoides K1 Cáncer K1 24 Ciencias de la Vida AB The transcription factor NF- B is overexpressed or constitutively activated in many cancer cells, where itinduces expression of antiapoptotic genes correlating with resistance to anticancer therapies. Small moleculesthat inhibit the NF- B signaling pathway could therefore be used to induce apoptosis in NF- B-overexpressingtumors and potentially serve as anticancer agents. We found that retinoid antagonist MX781 inhibited theactivation of NF- B-dependent transcriptional activity in different tumor cell lines. MX781 was able tocompletely inhibit tumor necrosis factor alpha-mediated activation of I B kinase (IKK), the upstream regulatorof NF- B. Inhibition of IKK activity resulted from direct binding of MX781 to the kinase, as demonstratedby in vitro inhibition studies. Two other molecules, MX3350-1 and CD2325, which are retinoic acidreceptor gamma-selective agonists, were capable of inhibiting IKK in vitro, although they exerted variableinhibition of IKK and NF- B activities in intact cells in a cell type-specific manner. However, N-(4-hydroxyphenyl)-retinamide, another apoptosis-inducing retinoid, and retinoic acid as well as other nonapoptoticretinoids did not inhibit IKK. Inhibition of IKK by the retinoid-related compounds and other small moleculescorrelated with reduced cell proliferation and increased apoptosis. Reduced cell viability was also observedafter overexpression of an IKK kinase-dead mutant or the I B superrepressor. The induction of apoptosisby the retinoid-related molecules that inhibited IKK was dependent on caspase activity but independent of theretinoid receptors. Thus, the presence of an excess of retinoic acid or a retinoid antagonist did not prevent theinhibition of IKK activation by MX781 and CD2325, indicating a retinoid receptor-independent mechanism ofaction. PB American Society for Microbiology SN 0270-7306 YR 2003 FD 2003 LK https://uvadoc.uva.es/handle/10324/47498 UL https://uvadoc.uva.es/handle/10324/47498 LA eng NO Molecular and Cellular Biology, 2003, vol. 23, n. 3, p. 1061-1074 NO Producción Científica DS UVaDOC RD 30-abr-2024