RESUMEN
Glioblastoma is the most common malignant brain tumor in adults. Standard treatment includes tumor resection, radio-chemotherapy and adjuvant chemotherapy with temozolomide (TMZ). TMZ methylates DNA, whereas O6-methylguanine DNA methyltransferase (MGMT) counteracts TMZ effects by removing the intended proteasomal degradation signal. Non-functional MGMT mediates the mismatch repair (MMR) system, leading to apoptosis after futile repair attempts. This study investigated the associations between MGMT promoter methylation, MGMT and MMR protein expression, and their effect on overall survival (OS) and progression-free survival (PFS) in patients with glioblastoma. MGMT promoter methylation was assessed in 42 treatment-naïve patients with glioblastoma WHO grade IV by pyrosequencing. MGMT and MMR protein expression was analyzed using immunohistochemistry. MGMT promoter methylation was present in 52%, whereas patients <70 years of age revealed a significantly longer OS using a log-rank test and a significance threshold of p ≤ 0.05. MGMT protein expression and methylation status showed no correlation. MMR protein expression was present in all patients independent of MGMT status and did not influence OS and PFS. Overall, MGMT promoter methylation implicates an improved OS in patients with glioblastoma aged <70 years. In the elderly, the extent of surgery has an impact on OS rather than the MGMT promoter methylation or protein expression.
Asunto(s)
Neoplasias Encefálicas , Glioblastoma , Adulto , Anciano , Humanos , Temozolomida/farmacología , Temozolomida/uso terapéutico , Glioblastoma/tratamiento farmacológico , Glioblastoma/genética , Supervivencia sin Progresión , Antineoplásicos Alquilantes/farmacología , Antineoplásicos Alquilantes/uso terapéutico , Dacarbazina/farmacología , Dacarbazina/uso terapéutico , Metilación , Reparación de la Incompatibilidad de ADN , Metilasas de Modificación del ADN/genética , Metilasas de Modificación del ADN/metabolismo , Neoplasias Encefálicas/tratamiento farmacológico , Neoplasias Encefálicas/genética , Neoplasias Encefálicas/metabolismo , O(6)-Metilguanina-ADN Metiltransferasa/genética , Enzimas Reparadoras del ADN/genética , Enzimas Reparadoras del ADN/metabolismo , Metilación de ADN , Proteínas Supresoras de Tumor/genética , Proteínas Supresoras de Tumor/metabolismoRESUMEN
A hallmark of infection by the pathogen Helicobacter pylori, which colonizes the human gastric epithelium, is the simultaneous activation of the classical and alternative nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) pathways, underlying inflammation and cell survival. Here, we report that the classical NF-κB target gene product A20 contributes to the negative regulation of alternative NF-κB signaling in gastric epithelial cells infected by H. pylori. Mechanistically, the de novo synthesized A20 protein interacts with tumor necrosis factor receptor-associated factor-interacting protein with forkhead-associated domain (TIFA) and thereby interferes with the association of TIFA with the NIK regulatory complex. We also show that alternative NF-κB activity contributes to the up-regulation of anti-apoptotic genes, such as baculoviral IAP repeat containing 2 (BIRC2), BIRC3 and B-cell lymphoma 2-related protein A1 (BCL2A1) in gastric epithelial cells. Furthermore, the observed over-expression of RelB in human gastric biopsies with type B gastritis and RelB-dependent suppression of apoptotic cell death emphasize an important role of the alternative NF-κB pathway in H. pylori infection.