RESUMO
Constitutive activation of Ras-proteins plays an important role in the development of aggressive colorectal carcinomas and several other types of cancer. Despite some progress in recent years in the case of K-Ras4B, until now not a single small molecule inhibitor has been identified that binds efficiently to Rheb and interrupts the protein-protein interactions with mTOR. We describe here a complementary approach that aims at inhibiting membrane insertion of Rheb and related Ras proteins by masking the crucial C-terminal CaaX-box with peptidomimetic receptors identified in combinatorial solid-phase libraries.
Assuntos
Proteínas Monoméricas de Ligação ao GTP/metabolismo , Proteínas ras/metabolismo , Espectrometria de Massas , Modelos Moleculares , Proteínas Monoméricas de Ligação ao GTP/química , Ressonância Magnética Nuclear Biomolecular , Espectrofotometria Ultravioleta , Serina-Treonina Quinases TOR/metabolismo , Proteínas ras/químicaRESUMO
We show for the first time that bisphenol A (10) has the capacity to interact directly with K-Ras and that Rheb weakly binds to bisphenol A (10) and 4,4'-biphenol derivatives. We have characterized these interactions at atomic resolution suggesting that these compounds sterically interfere with the Sos-mediated nucleotide exchange in H- and K-Ras. We show that 4,4'-biphenol (5) selectively inhibits Rheb signaling and induces cell death suggesting that this compound might be a novel candidate for treatment of tuberous sclerosis-mediated tumor growth. Our results propose a new mode of action for bisphenol A (10) that advocates a reduced exposure to this compound in our environment. Our data may lay the foundation for the future design of GTPase-selective antagonists with higher affinity to benefit of the treatment of cancer because K-Ras inhibition is regarded to be a promising strategy with a potential therapeutic window for targeting Sos in Ras-driven tumors.
Assuntos
Compostos Benzidrílicos/farmacologia , GTP Fosfo-Hidrolases/antagonistas & inibidores , Fatores de Troca do Nucleotídeo Guanina/metabolismo , Proteínas Monoméricas de Ligação ao GTP/metabolismo , Neuropeptídeos/metabolismo , Fenóis/farmacologia , Proteínas ras/metabolismo , Compostos Benzidrílicos/química , Compostos de Bifenilo/farmacologia , Guanosina Difosfato/metabolismo , Células HeLa , Humanos , Modelos Moleculares , Proteínas Monoméricas de Ligação ao GTP/antagonistas & inibidores , Neuropeptídeos/antagonistas & inibidores , Ressonância Magnética Nuclear Biomolecular , Fenóis/química , Proteínas Proto-Oncogênicas/metabolismo , Proteínas Proto-Oncogênicas p21(ras) , Proteína Enriquecida em Homólogo de Ras do Encéfalo , Resposta SOS em Genética/efeitos dos fármacosRESUMO
The synthesis and the structural and spectroscopic characterization of nonfluorescent, pyrene-based cyclic o-quinodimethanes are reported. These compounds react efficiently with nitric oxide (NO) in a formal cheletropic manner, by which the fluorescent aromatic pyrene system is regenerated. The NO trapping capabilities and kinetics of the fluorescent nitric oxide cheletropic traps (FNOCTs) are assessed in THF and buffered aqueous solution by ESR, UV/Vis, and fluorescence spectroscopy, by employing NO solutions and NO released from N-diazeniumdiolates (NONOates). Prototypal biological applications include the quantitation of NO production from cultured rat alveolar macrophages and the endothelium of porcine aorta, which demonstrate a sensitivity for NO detection in the nanomolar range.
