RESUMEN
Somatic gain-of-function mutations of GNAQ and GNA11, which encode α subunits of heterotrimeric Gαq/11 proteins, occur in about 85% of cases of uveal melanoma (UM), the most common cancer of the adult eye. Molecular therapies to directly target these oncoproteins are lacking, and current treatment options rely on radiation, surgery, or inhibition of effector molecules downstream of these G proteins. A hallmark feature of oncogenic Gαq/11 proteins is their reduced intrinsic rate of hydrolysis of guanosine triphosphate (GTP), which results in their accumulation in the GTP-bound, active state. Here, we report that the cyclic depsipeptide FR900359 (FR) directly interacted with GTPase-deficient Gαq/11 proteins and preferentially inhibited mitogenic ERK signaling rather than canonical phospholipase Cß (PLCß) signaling driven by these oncogenes. Thereby, FR suppressed the proliferation of melanoma cells in culture and inhibited the growth of Gαq-driven UM mouse xenografts in vivo. In contrast, FR did not affect tumor growth when xenografts carried mutated B-RafV600E as the oncogenic driver. Because FR enabled suppression of malignant traits in cancer cells that are driven by activating mutations at codon 209 in Gαq/11 proteins, we envision that similar approaches could be taken to blunt the signaling of non-Gαq/11 G proteins.
Asunto(s)
Depsipéptidos/farmacología , Sistemas de Liberación de Medicamentos , Subunidades alfa de la Proteína de Unión al GTP Gq-G11 , Subunidades alfa de la Proteína de Unión al GTP , Mutación con Ganancia de Función , Melanoma , Proteínas de Neoplasias , Neoplasias de la Úvea , Animales , Línea Celular Tumoral , Depsipéptidos/química , Subunidades alfa de la Proteína de Unión al GTP/antagonistas & inhibidores , Subunidades alfa de la Proteína de Unión al GTP/genética , Subunidades alfa de la Proteína de Unión al GTP/metabolismo , Subunidades alfa de la Proteína de Unión al GTP Gq-G11/antagonistas & inhibidores , Subunidades alfa de la Proteína de Unión al GTP Gq-G11/genética , Subunidades alfa de la Proteína de Unión al GTP Gq-G11/metabolismo , Células HEK293 , Humanos , Melanoma/tratamiento farmacológico , Melanoma/enzimología , Melanoma/genética , Melanoma/patología , Ratones , Ratones Endogámicos NOD , Ratones SCID , Proteínas de Neoplasias/antagonistas & inhibidores , Proteínas de Neoplasias/genética , Proteínas de Neoplasias/metabolismo , Neoplasias de la Úvea/tratamiento farmacológico , Neoplasias de la Úvea/enzimología , Neoplasias de la Úvea/genética , Neoplasias de la Úvea/patología , Ensayos Antitumor por Modelo de XenoinjertoRESUMEN
Despite the discovery of heterotrimeric αßγ G proteins â¼25 years ago, their selective perturbation by cell-permeable inhibitors remains a fundamental challenge. Here we report that the plant-derived depsipeptide FR900359 (FR) is ideally suited to this task. Using a multifaceted approach we systematically characterize FR as a selective inhibitor of Gq/11/14 over all other mammalian Gα isoforms and elaborate its molecular mechanism of action. We also use FR to investigate whether inhibition of Gq proteins is an effective post-receptor strategy to target oncogenic signalling, using melanoma as a model system. FR suppresses many of the hallmark features that are central to the malignancy of melanoma cells, thereby providing new opportunities for therapeutic intervention. Just as pertussis toxin is used extensively to probe and inhibit the signalling of Gi/o proteins, we anticipate that FR will at least be its equivalent for investigating the biological relevance of Gq.
