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: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.

Project description:Mesenchymal stem cells (MSCs) are known to induce the conversion of activated T-cells into regulatory T-cells in vitro. The marker CD69 is a target of canonical NF-κB signaling and is transiently expressed upon activation; however, stable CD69 expression defines cells with immunoregulatory properties. Given its enormous therapeutic potential, we explored the molecular mechanisms underlying the induction of regulatory cells by MSCs. Peripheral blood CD3+ T-cells were activated and cultured in the presence or absence of MSCs. CD4+ cell mRNA expression was then characterized by microarray analysis. The drug BAY11-7082 and a siRNA against RELB were used to explore the differential roles of canonical and non-canonical NF-κB signaling, respectively. Flow cytometry and real-time PCR were used for analyses. Genes with immunoregulatory functions, CD69 and non-canonical NF-κB subunits (RELB and NFKB2) were all expressed at higher levels in lymphocytes co-cultured with MSCs. The frequency of CD69+ cells among lymphocytes cultured alone progressively decreased after activation. In contrast, the frequency of CD69+ cells increased significantly following activation in lymphocytes co-cultured with MSCs. Inhibition of canonical NF-κB signaling by BAY immediately following activation blocked the induction of CD69; however, inhibition of canonical NF-κB signaling on the 3rd day further induced the expression of CD69. Furthermore, late expression of CD69 was inhibited by RELB siRNA. These results indicate that the canonical NF-κB pathway controls the early expression of CD69 after activation; however, in an immunoregulatory context, late and sustained CD69 expression is promoted by the non-canonical pathway and is inhibited by canonical NF-κB signaling. In order to study the molecular basis by which Multipotent Mesenchymal Stromal/Stem Cells (MSC) exert their immune regulatory function, immunomagnetically purified CD3+ T-cells from the peripheral blood of 3 individuals were activated and cultured in the presence or absence of MSCs. Following 5 days, CD4+ and CD8+ T-cells were further immunomagnetically selected and their gene expression profiles were obtained by microarrays and compared. Paired samples from 3 individuals were used for this analysis.

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