RESUMO
Sirtuins (SIRTs) are a family of histone deacetylases, which widely regulate cellular metabolism and are also involved in DNA repair. Rap1-interacting factor 1 (Rif1) and O6-alkylguanine DNA alkyltransferase (MGMT) are DNA-repair enzymes, which may potentially be involved in resistance to treatment of classical Hodgkin lymphoma (HL). We assessed the expression levels of (previously unstudied) SIRT1, SIRT4, SIRT6, Rif1, and MGMT immunohistochemically in 85 patients with untreated classical HL. Aberrant distributions of SIRT1, SIRT4, and SIRT6 were detected in Hodgkin neoplastic Reed-Sternberg (RS) cells compared with reactive elements. Low-level expression of both Rif1 and SIRT6 predicted dismal relapse-free survival in radiotherapy-treated patients (multivariate analysis; HR 8.521; 95% CI 1.714-42.358; p = .0088). Expression levels of SIRT1, 4, and 6 were abnormally distributed in RS cells, suggesting a putative role of aberrant acetylation in classical HL carcinogenesis. Rif1 and SIRT6 may also have substantial prognostic and even predictive roles in classical HL.
Assuntos
Biomarcadores Tumorais/metabolismo , Doença de Hodgkin/mortalidade , Recidiva Local de Neoplasia/mortalidade , Radioterapia/mortalidade , Células de Reed-Sternberg/patologia , Sirtuínas/metabolismo , Proteínas de Ligação a Telômeros/metabolismo , Acetilação , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Feminino , Seguimentos , Doença de Hodgkin/metabolismo , Doença de Hodgkin/patologia , Doença de Hodgkin/radioterapia , Humanos , Masculino , Pessoa de Meia-Idade , Recidiva Local de Neoplasia/metabolismo , Recidiva Local de Neoplasia/patologia , Recidiva Local de Neoplasia/radioterapia , Prognóstico , Radioterapia/efeitos adversos , Células de Reed-Sternberg/efeitos da radiação , Taxa de Sobrevida , Adulto JovemRESUMO
AP-1 family transcription factors have been implicated in the control of proliferation, apoptosis and malignant transformation. However, their role in oncogenesis is unclear and no recurrent alterations of AP-1 activities have been described in human cancers. Here, we show that constitutively activated AP-1 with robust c-Jun and JunB overexpression is found in all tumor cells of patients with classical Hodgkin's disease. A similar AP-1 activation is present in anaplastic large cell lymphoma (ALCL), but is absent in other lymphoma types. Whereas c-Jun is up-regulated by an autoregulatory process, JunB is under control of NF-kappa B. Activated AP-1 supports proliferation of Hodgkin cells, while it suppresses apoptosis of ALCL cells. Furthermore, AP-1 cooperates with NF-kappa B and stimulates expression of the cell-cycle regulator cyclin D2, proto-oncogene c-met and the lymphocyte homing receptor CCR7, which are all strongly expressed in primary HRS cells. Together, these data suggest an important role of AP-1 in lymphoma pathogenesis.
