Project description:Although therapy responsiveness to therapy in Burkitt lymphoma (BL) is high, relapsed disease and and chemoresistance remain a clinical challenge, and complete mechanisms underlying BL chemoresistance and how it can be circumvented is yet to be fully elucidated. In this study we present data showing that chymotrypsin-like serine proteases inhibitor Nα-tosyl-L-phenylalanine chloromethylketone (TPCK) and specific NF-κB inhibitor Bay-11 7082 can induce caspase-independent apoptosis in chemoresistant BL cells. We also demonstrate that both TPCK and Bay-11 7082-treatment leads to decreased NF-κB nuclear activity and that this is associated with sensitization of chemoresistant Burkitt lymphoma cells. Furthermore we investigated global transcriptional changes induced by Bay-11 7082 and TPCK in the DG-75 and Raji cell lines, respectively, by microarray analysis using Illumina BeadChips. TPCK-treatment of Raji and DG-75 cells resulted in 59 and 21 differently expressed genes, respectively, while Bay-11-treated Raji and DG-75 cells displayed 1403 and 8 differently expressed genes, respectively. Gene Ontology (GO) categorization confirmed enrichment of multiple GOs in Bay 11-treated Raji and DG-75 cells. Fifty percent of the 61 categories in Raji cells were categories sorting under Biological Processes and represented mostly increased gene expression. In DG-75 cells Bay-11 7082 induced significant gene ontology enrichment in only two categories, where the increased/decreased ratio was 1:1. Further unsupervised and supervised bioinformatics processing by Ingenuity Pathway Analysis indicated significant networks in response to TPCK and Bay 11 respectively, including association to NF-κB. Bay-11 7082 demonstrated deregulated NF-κB related members of receptor mediated cell death signaling, i.e TRAF2 and TRADD, as well as deregulated members of the NF-κB signaling pathway from the cytoplasmic compartment, i.e RELB, in Raji cells. Comparably NF-κB network analysis of Raji- and DG-75 cells treated with Bay-11 7082 and Raji cells treated with TPCK demonstrated deregulation of NF-κB target genes CD69 and IL8. These data indicates that NF-kB may play a role in overcoming chemoresistance in BL cells with defective classical apoptosis signaling. NF-κB network analysis of Raji- and DG-75 cells treated with Bay-11 7082 and Raji cells treated with TPCK

Project description:Proper regulation of nuclear factor κB (NF-κB) transcriptional activity is required for normal lymphocyte function, and deregulated NF-κB signaling can facilitate lymphomagenesis. We demonstrate that the API2-MALT1 fusion oncoprotein created by the recurrent t(11;18)(q21;q21) in mucosa-associated lymphoid tissue (MALT) lymphoma induces proteolytic cleavage of NF-κB–inducing kinase (NIK) at arginine 325. NIK cleavage requires the concerted actions of both fusion partners and generates a C-terminal NIK fragment that retains kinase activity and is resistant to proteasomal degradation. The resulting deregulated NIK activity is associated with constitutive noncanonical NF-κB signaling, enhanced B cell adhesion, and apoptosis resistance. Our study reveals the gain-of-function proteolytic activity of a fusion oncoprotein and highlights the importance of the noncanonical NF-κB pathway in B lymphoproliferative disease. This study compares nine t(11;18)-positive MALT lymphomas (8 from the stomach and 1 from lung) and eight translocation negative MALT lymphomas (all from the stomach) using gene set enrichment analysis (GSEA). All cases were subjected to Affymetrix U133A and U133B microarray analysis. The cases used in this study are the same cases used for the study by Hamoudi et al. (2010) entitled "Differential expression of NF-kB target genes in MALT lymphoma with and without chromosome translocation: insights into molecular mechanism" with GEO reference number: GSE18736 and PubMed ID: http://www.ncbi.nlm.nih.gov/pubmed/20520640 All cases were subjected to non-specific filtering to eliminate non-variant probes, then the U133A and U133B probes were collapsed and the collapsed set was subjected to GSEA using the NF-kB target gene set as described in Hamoudi et al. (2010) study mentioned above. The 34 samples in this study are identical to the ones done in the previous series except that the gene set enrichment was done on just those 34 samples and not the complete set.

Project description:Although therapy responsiveness to therapy in Burkitt lymphoma (BL) is high, relapsed disease and and chemoresistance remain a clinical challenge, and complete mechanisms underlying BL chemoresistance and how it can be circumvented is yet to be fully elucidated. In this study we present data showing that chymotrypsin-like serine proteases inhibitor Nα-tosyl-L-phenylalanine chloromethylketone (TPCK) and specific NF-κB inhibitor Bay-11 7082 can induce caspase-independent apoptosis in chemoresistant BL cells. We also demonstrate that both TPCK and Bay-11 7082-treatment leads to decreased NF-κB nuclear activity and that this is associated with sensitization of chemoresistant Burkitt lymphoma cells. Furthermore we investigated global transcriptional changes induced by Bay-11 7082 and TPCK in the DG-75 and Raji cell lines, respectively, by microarray analysis using Illumina BeadChips. TPCK-treatment of Raji and DG-75 cells resulted in 59 and 21 differently expressed genes, respectively, while Bay-11-treated Raji and DG-75 cells displayed 1403 and 8 differently expressed genes, respectively. Gene Ontology (GO) categorization confirmed enrichment of multiple GOs in Bay 11-treated Raji and DG-75 cells. Fifty percent of the 61 categories in Raji cells were categories sorting under Biological Processes and represented mostly increased gene expression. In DG-75 cells Bay-11 7082 induced significant gene ontology enrichment in only two categories, where the increased/decreased ratio was 1:1. Further unsupervised and supervised bioinformatics processing by Ingenuity Pathway Analysis indicated significant networks in response to TPCK and Bay 11 respectively, including association to NF-κB. Bay-11 7082 demonstrated deregulated NF-κB related members of receptor mediated cell death signaling, i.e TRAF2 and TRADD, as well as deregulated members of the NF-κB signaling pathway from the cytoplasmic compartment, i.e RELB, in Raji cells. Comparably NF-κB network analysis of Raji- and DG-75 cells treated with Bay-11 7082 and Raji cells treated with TPCK demonstrated deregulation of NF-κB target genes CD69 and IL8. These data indicates that NF-kB may play a role in overcoming chemoresistance in BL cells with defective classical apoptosis signaling.

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