1 ABSTRACT B-cell non-Hodgkin lymphomas (B-NHL) represent the most common mature lymphoproliferative diseases. B-NHL arise at different stages of B-cell development and represent their malignant counterpart. Diffuse large B-cell lymphoma (DLBCL) and mantle cell lymphoma (MCL) are aggressive types of B-NHLs. Deregulation of cell cycle control, inhibition of apoptosis or abnormal DNA damage response play a key role in the pathogenesis of DLBCL and MCL. Aberrant activation of several signaling pathways that further promote survival, cell proliferation or affect the tumor microenvironment have been recently recognized. Increased understanding of the oncogenic mechanisms implicated in pathogenesis of B-NHL lead to development of novel agents that target the oncogenic drivers of distinct lymphoma subtypes. MCL is an aggressive subtype of B-NHL associated with poor prognosis. In vivo models of human MCL for experimental therapy are however scarce. We established and characterized several mouse models of human MCL by xenotransplantation of either primary cells or established cell lines into immunodeficient mice (publication no 1). We demonstrated that engrafted MCL cells displayed complex changes of gene expression profile, phenotype and sensitivity to cytotoxic agents compared to the original in vitro growing...

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High grade aggressive lymphomas have high mortality. By their nature, more than 40% of patients die from these diseases even with the improved treatment strategies currently available for oncology patients. The characteristic feature is that they are functionally heterogeneous and therefore have different biological and molecular signatures which make it difficult for all groups to respond to same line of treatment. Based on the above, I set out to look at the impact of viral and cellular gene products on these groups of diseases: In chapter 3 I developed monoclonal antibodies against HERV‐K10. I subsequently investigated their expressions in aggressive lymphomas including Diffuse Large B‐cell lymphoma, Hodgkin’s lymphoma and Primary CNS lymphomas. I showed HERV‐K10 is expressed in cell lines of aggressive lymphomas, but not in paraffin‐embedded tissues. In chapter 4 I showed that the expression of ATM using immune‐histochemistry techniques in aggressive lymphomas does offer a guide to prognosis and treatment. Nearly 30% of Diffuse Large B‐cell lymphomas express ATM, 55% of Hodgkin’s lymphomas and more than 80% of Primary CNS lymphomas. I also showed there is a correlation of ATM expression and EBV‐driven aggressive lymphomas and that this has a poor prognostic significance. Chapter 5 analysed the results obtained by generating, validating and evaluating data base of DLBCL and PCNSL from a retrospective cohort over a 17‐year period. The results confirmed that prognostic indicators including ATM, S1PR2, Autotaxin and EBV using immuno‐histochemistry techniques help with categorising aggressive lymphomas into different prognostic groups and does influence future management. In summary, my results showed there is a critical place for immuno‐histochemistry techniques in convincingly helping understand the expressions of viral and cellular gene products in aggressive lymphomas and in contributing positively to their management.

Diffuse large B-cell lymphoma (DLBCL) is the most common type of non-Hodgkin lymphoma. It is a molecular and prognostic heterogeneous disease. Three main genetic subtypes are called germinal center-like DLBCL (GC-like DLBCL), non-germinal center-like DLBCL (nonGC-like DLBCL) and primary mediastinal B-cell lymphoma (PMBL). These subtypes can be reliably distinguished only with usage of gene expression profiling (GEP). The GEP method can be applied only when fresh frozen tissue is available. The method is technically difficult and expensive. Thus, it is not used routinely. Since the DLBCL subtypes differ in prognosis, it is extremely important to be able to distinguish them. The presented thesis is focused on distinguishing of PMBL diagnosis in the group of DLBCL. Easily stored formalin-fixed, paraffin-embedded tissue (FFPE) and gene expression analysis using real-time quantitative polymerase chain reaction (RTqPCR) are used. In the first step, PMBL and DLBCL cases were distinguished with an internationally accepted clinical-pathological method. The agreement between clinical-pathological diagnosis and GEP is only 76%. In the presented text a genetic algorithm for PMBL/DLBCL distinguishing is suggested. It uses three carefully chosen genes and their expression is measured with RTqPCR. Both, the...

Diffuse large B-cell lymphoma (DLBCL) is the most common type of non-Hodgkin lymphoma. It is a molecular and prognostic heterogeneous disease. Three main genetic subtypes are called germinal center-like DLBCL (GC-like DLBCL), non-germinal center-like DLBCL (nonGC-like DLBCL) and primary mediastinal B-cell lymphoma (PMBL). These subtypes can be reliably distinguished only with usage of gene expression profiling (GEP). The GEP method can be applied only when fresh frozen tissue is available. The method is technically difficult and expensive. Thus, it is not used routinely. Since the DLBCL subtypes differ in prognosis, it is extremely important to be able to distinguish them. The presented thesis is focused on distinguishing of PMBL diagnosis in the group of DLBCL. Easily stored formalin-fixed, paraffin-embedded tissue (FFPE) and gene expression analysis using real-time quantitative polymerase chain reaction (RTqPCR) are used. In the first step, PMBL and DLBCL cases were distinguished with an internationally accepted clinical-pathological method. The agreement between clinical-pathological diagnosis and GEP is only 76%. In the presented text a genetic algorithm for PMBL/DLBCL distinguishing is suggested. It uses three carefully chosen genes and their expression is measured with RTqPCR. Both, the...