RESUMEN
Enhancer of Zeste homologue 2 (EZH2) belongs to the polycomb repressive complex 2 and catalyzes the methylation of histone H3 lysine 27. These pivotal epigenetic marks are altered in many cancers, including melanoma, as a result of EZH2 overexpression. Here, we show that the non-canonical-NF-kB pathway accounts for most of the NF-kB activity in melanoma cells, in contrast to non-cancer cells. We identify the non-canonical-NF-kB pathway as a key regulator of EZH2 expression in melanoma. We show a striking correlation between NF-kB2 and EZH2 expression in human melanoma metastases. We demonstrate that inhibition of the non-canonical NF-kB pathway by targeting NF-kB2/p52 or the upstream kinase NIK restores the senescence program in melanoma cells through the decrease of EZH2. On the contrary, the overexpression of NF-kB2/p52 in normal human melanocytes prevents stress- and oncogene-induced senescence. Finally, we show in mouse models that the inhibition of the non-canonical NF-kB pathway restores senescence and induces a dramatic reduction in tumor growth compared with controls, thus providing potential drug targets for the re-induction of senescence in melanoma and other cancers where EZH2 is overexpressed.
Asunto(s)
Proteína Potenciadora del Homólogo Zeste 2/genética , Melanoma/genética , Melanoma/metabolismo , Animales , Línea Celular Tumoral , Regulación hacia Abajo , Proteína Potenciadora del Homólogo Zeste 2/metabolismo , Xenoinjertos , Humanos , Melanoma/patología , Ratones , Ratones Desnudos , Subunidad p52 de NF-kappa B/biosíntesis , Subunidad p52 de NF-kappa B/genética , Subunidad p52 de NF-kappa B/metabolismo , Activación TranscripcionalRESUMEN
PURPOSE: Systemic granulomatosis (SG) are frequently encountered in internal medicine. Despite a large list of aetiologies, the investigations remain often negative leading to the diagnosis of atypical sarcoidosis. The spectrum of the causes, as well as evolution of these SG is not clearly delineated in the literature. METHOD: We analyzed the case reports of all but tuberculous GS submitted at the National Meetings of the National French Society of Internal Medicine from 1990 to 2006. RESULTS: Sixty-seven cases were included in the study. The average age at the beginning of the symptoms was 47.8 years and 28.4% of the patients were female. The median diagnostic delay was one year. General symptoms were present in 73.1% of the cases. The involved organs were the liver (46.3%), lungs (25.4%), lymph nodes (22.4%), digestive tract (16.4%), skin (16.4%), spleen (14.9%). The granuloma were detected mainly in the liver (38.8%), lymph nodes (17.9%), bone marrow (16.4%) and lungs (11.9%). Elevated erythrocyte sedimentation rate or increased C reactive protein serum levels were noted in 65.6% of the patients. Before diagnosis, 19.4% of the patients received a corticotherapy. The most common diagnoses were infections (65.6%) followed by drugs (19.5%), "toxic substances" or various foreign bodies (5.9%), neoplasias (5.9%) and immune deficiencies (3%). The evolution was favourable in 80% of the cases but 8.3% of the patients died. The disease course of the patients having received a corticotherapy prior to the diagnosis was more unfavourable with a death rate of 45%. CONCLUSION: In atypical sarcoidosis (fever, advanced age, increased acute phase reactants...) a specific aetiology and especially an infectious disease should be ruled out before considering the diagnosis of sarcoidosis. Corticotherapy is a factor of poor prognosis.