Mantle cell lymphoma (MCL) is characterized by the translocation t(11;14)(q13;q32) leading to an overexpression of cyclin D1, a mediator of G1-S phase transition. Thus MCL is regarded as a paradigm of lymphoma with a dysregulated cell cycle. The proliferation rate of MCL is in fact a strong predictor of outcome. We analyzed proteins that are expressed at defined cell cycle phases, such as Ki67, survivin and phosphorylated histone H3 as well as cyclin D1, p53 and p27, on the cellular level by immunofluorescence double stainings in MCL biopsy specimens. Unexpectedly, we did not detect a shortening of early phases in MCL in vivo. Despite the control of the immunoglobulin enhancer, cyclin D1 was expressed in a cell cycle-dependent manner. However, the proliferating Ki67-positive tumor cells expressed low amounts of cyclin D1. Therefore, the expression of cyclin D1 appears not to be the driving factor behind the total proliferation rate of MCL.
Anaplastic lymphoma kinase-positive anaplastic large T-cell lymphoma is characterized by morphological variability. Morphological variants (non-common subtype) are associated with a poor outcome. They display abundant reactive bystander cells admixed with the lymphoma cells. So far, the difficulty in distinguishing lymphoma cells from bystander cells by visual inspection has prevented detailed and reliable immunophenotypic analysis using conventional immunohistochemistry. To overcome these limitations, we analyzed 124 cases of pediatric anaplastic lymphoma kinase-positive anaplastic large cell lymphoma treated within clinical trials using immunofluorescence multi-staining and digital image analysis combining antibodies against anaplastic lymphoma kinase to specifically identify lymphoma cells with antibodies against CD30, CD3, CD5, CD8, Ki67 and phosphorylated STAT3. Non-common type anaplastic lymphoma kinase-positive anaplastic large cell lymphomas express CD8 more frequently than common type anaplastic lymphoma kinase-positive anaplastic large cell lymphomas (35.4% and 5.6%, respectively; P=0.0002). CD8 expression was associated with a poorer outcome. Importantly, in a multivariate analysis including clinical risk factors, histological subtype and CD8 expression, CD8-positivity proved to be an independent prognostic predictor of worse outcome (hazard ratio for survival 3.38, P=0.042).
Based on the assumption that molecular mechanisms involved in cancerogenesis are characterized by groups of coordinately expressed genes, we developed and validated a novel method for analyzing transcriptional data called Correlated Gene Set Analysis (CGSA). Using 50 extracted gene sets we identified three different profiles of tumors in a cohort of 364 Diffuse large B-cell (DLBCL) and related mature aggressive B-cell lymphomas other than Burkitt lymphoma. The first profile had high level of expression of genes related to proliferation whereas the second profile exhibited a stromal and immune response phenotype. These two profiles were characterized by a large scale gene activation affecting genes which were recently shown to be epigenetically regulated, and which were enriched in oxidative phosphorylation, energy metabolism and nucleoside biosynthesis. The third and novel profile showed only low global gene activation similar to that found in normal B cells but not cell lines. Our study indicates novel levels of complexity of DLBCL with low or high large scale gene activation related to metabolism and biosynthesis and, within the group of highly activated DLBCLs, differential behavior leading to either a proliferative or a stromal and immune response phenotype.
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