ABSTRACT
We have used polysome profiling coupled to microarray analysis to examine the translatome of a panel of peripheral blood (PB) B cells isolated from 34 chronic lymphocytic leukaemia (CLL) patients. We have identified a 'ribosome-related' signature in CLL patients with mRNAs encoding for ribosomal proteins and factors that modify ribosomal RNA, e.g. DKC1 (which encodes dyskerin, a pseudouridine synthase), showing reduced polysomal association and decreased expression of the corresponding proteins. Our data suggest a general impact of dyskerin dysregulation on the translational apparatus in CLL and importantly patients with low dyskerin levels have a significantly shorter period of overall survival following treatment. Thus, translational dysregulation of dyskerin could constitute a mechanism by which the CLL PB B cells acquire an aggressive phenotype and thus have a major role in oncogenesis.
Subject(s)
Gene Expression Profiling , Leukemia, Lymphocytic, Chronic, B-Cell/blood , Leukemia, Lymphocytic, Chronic, B-Cell/genetics , Ribosomes/metabolism , Cell Cycle Proteins/genetics , Cell Cycle Proteins/metabolism , Cell Nucleolus/metabolism , Down-Regulation/genetics , Eukaryotic Initiation Factors/genetics , Eukaryotic Initiation Factors/metabolism , Gene Expression Regulation, Leukemic , Humans , Immunoblotting , Leukemia, Lymphocytic, Chronic, B-Cell/drug therapy , Leukemia, Lymphocytic, Chronic, B-Cell/pathology , Nuclear Proteins/genetics , Nuclear Proteins/metabolism , Polyribosomes/metabolism , Protein Biosynthesis , RNA, Ribosomal/metabolism , Ribosomal Proteins/genetics , Ribosomal Proteins/metabolism , Survival Analysis , Treatment OutcomeABSTRACT
Dysregulated expression of factors that control protein synthesis is associated with poor prognosis of many cancers, but the underlying mechanisms are not well defined. Analysis of the diffuse large B-cell lymphoma (DLBCL) translatome revealed selective upregulation of mRNAs encoding anti-apoptotic and DNA repair proteins. We show that enhanced synthesis of these proteins in DLBCL is mediated by the relief of repression that is normally imposed by structure in the 5'-untranslated regions of their corresponding mRNAs. This process is driven by signaling through mammalian target of rapamycin, resulting in increased synthesis of eukaryotic initiation factor (eIF) 4B complex (eIF4B), a known activator of the RNA helicase eIF4A. Reducing eIF4B expression alone is sufficient to decrease synthesis of proteins associated with enhanced tumor cell survival, namely DAXX, BCL2 and ERCC5. Importantly, eIF4B-driven expression of these key survival proteins is directly correlated with patient outcome, and eIF4B, DAXX and ERCC5 are identified as novel prognostic markers for poor survival in DLBCL. Our work provides new insights into the mechanisms by which the cancer-promoting translational machinery drives lymphomagenesis.
Subject(s)
Eukaryotic Initiation Factors/metabolism , Lymphoma, Large B-Cell, Diffuse/metabolism , 5' Untranslated Regions , Cell Line, Tumor , Electrophoresis, Polyacrylamide Gel , Humans , Lymphoma, Large B-Cell, Diffuse/pathology , Oligonucleotide Array Sequence Analysis , RNA, Messenger/genetics , Reverse Transcriptase Polymerase Chain Reaction , Up-RegulationABSTRACT
We have investigated the time course of the coagulation and fibrinolytic changes during moderate surgical trauma (elective reduction mammoplasty) in the absence of other confounding factors that could affect haemostasis. Specific markers for coagulation (prothrombin fragment 1.2 (F1.2), thrombin-antithrombin III complex (TAT)) and fibrinolysis (plasmin-antiplasmin complex (PAP) and D-dimer) were examined. Blood samples were obtained in 20 ASA I anaesthetized female patients at T0 (before operation), T75 (during operation) and T150 (before the end of operation). There was a progressive increase in blood loss during operation:mean 110 (SD 80) ml at T75 and 470 (180) ml at T150. This was associated with a significant increase in plasma concentrations of F1.2, PAP and D-dimer at T150 only (P < 0.05 vs T0). We conclude that moderate surgical trauma with blood losses greater than 300 ml can activate thrombin generation and fibrinolysis during operation.
