Project description:Diffuse large B-cell lymphoma (DLBCL) is the most common type of lymphoid neoplasm in the world representing 30-40% of all lymphomas. Standard immunochemotherapy (cyclophosphamide, doxorubicin, vincristine, prednisone and rituximab) ensures cure in 60 to 65% of patients, while the rest progress or relapse. While advances have been made in the treatment of DLBCL, especially with the addition of rituximab, it is now apparent that there may be significant differences in prognosis that are related to the cell of origin, and that this disease is heterogeneous and novel treatment options are needed. It has been hypothesized that the combination of HDACI and hypomethylating agents might be a new approach to the treatment of relapsed or refractory DLBCL. This combination is thought to disrupt the transcription repressor complex consisting of methyl binding domain proteins (MBDP) and histone deacetylases (HDACs). We have explored the effect of different HDACI and decitabine combinations in in vitro and in vivo models of DLBCL. These data suggest a class effect, with all four HDACI (panobinostat, belinostat, vorinostat, depsipeptide) synergizing with decitabine in cytotoxicity assay across the spectrum of DLBCL cells. Synergy was validated in a number of other assays including a caspase 3 activation and apoptosis. Furthermore, the combination of panobinostat and decitabine induced markedly increased histone acetylation. The in vitro observations were confirmed in an in vivo murine xenograft experiment with the Ly1 DLBCL line. Genome wide methylation analysis and gene expression profiling demonstrated that the combination of these two epigenetic therapies produced a unique gene expression profile compared to the samples treated with single drugs. These data strongly support the potential therapeutic role of a combinatorial epigenetic platform for the treatment of B-cell lymphomas, in particular in patients with DLBCL. Clearly, future studies will need to focus on integrating the appropriate correlative studies, with an effort to identify and or validate biomarkers of activity with these combinations. The likelihood moving forward is that the mechanism of action of these combinations may vary from disease context to disease context. Genome-wide array findings from these kinds of studies could be expanded to samples from patients on clinical trials to identify novel biomarkers of response, leading to the rational treatment of individual diseases based upon the underlying pathogenesis. We have used single samples from three DLBCL cell lines (biological replicates) which were treated with DMSO, decitabine alone, panobinostat alone and their combination for 48h - total of 12 samples

Project description:Silencing of genes that suppress the malignant phenotype by DNA methylation spurred an interest in the clinical use of epigenetic reprogramming agents. Single therapy is unlikely to be curative in the context of a heterogeneous disease such as Diffuse Large B cell Lymphomas (DLBCL). The combination of DNA demethylating drugs could increase the chance to respond to classical and new treatments. We found that DLBCL cell lines respond heterogeneously to DNA demethylating agents. In sensitive cell lines, 5-aza-2’-deoxycytidine induced a genomic signature similar to that of doxorubicin, the most important drug of the combinatorial chemotherapy regimen for DLBCL treatment. Accordingly, the combination of 5-aza-2’-deoxycytidine and doxorubicin proved to be synergistic in cell killing in vitro and in vivo for DLBCL cell lines individually responsive to these drugs. In doxorubicin resistant cell lines, long-term exposure to low-dose of 5-aza-2’-deoxycytidine induces DNA demethylation and subsequent doxorubicin sensitization in vitro and in vivo. This later effect correlates with SMAD1 demethylation. SMAD1 is epigenetically silenced in doxorubicin-resistant DLBCL cells and DLBCL patients with poor prognostic. In addition, we found that DNA demethylating agents can sensitize primary DLBCL cells to doxorubicin. Primary cells obtained from a DLBCL patient treated with 5-azacytidine shows SMAD1 demethylation and ex vivo sensitization to multiple drugs. Therefore, DNA demethylating drugs can reprogram otherwise resistant DLBCL cells to respond to chemotherapy agents without increasing the toxicity to normal tissues. Our data also indicate that DNA methylation and consequent suppression of SMAD1 expression represent a previously undescribed molecular mechanism of chemoresistance in DLBCL that can be further exploit for therapy. A microarray study using genomic DNA from different DLBCL cell lines before any treatment. Two to four biological replicates by cell line. The HELP data wil be used to find genes hypermethylated in resistant cell lines compared to sensitive cell lines to doxorubicin and other drugs.

Project description:Silencing of genes that suppress the malignant phenotype by DNA methylation spurred an interest in the clinical use of epigenetic reprogramming agents. Single therapy is unlikely to be curative in the context of a heterogeneous disease such as Diffuse Large B cell Lymphomas (DLBCL). The combination of DNA demethylating drugs could increase the chance to respond to classical and new treatments. We found that DLBCL cell lines respond heterogeneously to DNA demethylating agents. In sensitive cell lines, 5-aza-2M-bM-^@M-^Y-deoxycytidine induced a genomic signature similar to that of doxorubicin, the most important drug of the combinatorial chemotherapy regimen for DLBCL treatment. Accordingly, the combination of 5-aza-2M-bM-^@M-^Y-deoxycytidine and doxorubicin proved to be synergistic in cell killing in vitro and in vivo for DLBCL cell lines individually responsive to these drugs. In doxorubicin resistant cell lines, long-term exposure to low-dose of 5-aza-2M-bM-^@M-^Y-deoxycytidine induces DNA demethylation and subsequent doxorubicin sensitization in vitro and in vivo. This later effect correlates with SMAD1 demethylation. SMAD1 is epigenetically silenced in doxorubicin-resistant DLBCL cells and DLBCL patients with poor prognostic. In addition, we found that DNA demethylating agents can sensitize primary DLBCL cells to doxorubicin. Primary cells obtained from a DLBCL patient treated with 5-azacytidine shows SMAD1 demethylation and ex vivo sensitization to multiple drugs. Therefore, DNA demethylating drugs can reprogram otherwise resistant DLBCL cells to respond to chemotherapy agents without increasing the toxicity to normal tissues. Our data also indicate that DNA methylation and consequent suppression of SMAD1 expression represent a previously undescribed molecular mechanism of chemoresistance in DLBCL that can be further exploit for therapy. A microarray study using double-stranded cDNA from different DLBCL cell lines before any treatment. Two biological replicates by cell line. The gene expression will be used to find gene expression signatures between sensitive and resistant cell lines to chemotherapeutics.

Project description:Diffuse large B-cell lymphoma (DLBCL) is the most common type of lymphoid neoplasm in the world representing 30-40% of all lymphomas. Standard immunochemotherapy (cyclophosphamide, doxorubicin, vincristine, prednisone and rituximab) ensures cure in 60 to 65% of patients, while the rest progress or relapse. While advances have been made in the treatment of DLBCL, especially with the addition of rituximab, it is now apparent that there may be significant differences in prognosis that are related to the cell of origin, and that this disease is heterogeneous and novel treatment options are needed. It has been hypothesized that the combination of HDACI and hypomethylating agents might be a new approach to the treatment of relapsed or refractory DLBCL. This combination is thought to disrupt the transcription repressor complex consisting of methyl binding domain proteins (MBDP) and histone deacetylases (HDACs). We have explored the effect of different HDACI and decitabine combinations in in vitro and in vivo models of DLBCL. These data suggest a class effect, with all four HDACI (panobinostat, belinostat, vorinostat, depsipeptide) synergizing with decitabine in cytotoxicity assay across the spectrum of DLBCL cells. Synergy was validated in a number of other assays including a caspase 3 activation and apoptosis. Furthermore, the combination of panobinostat and decitabine induced markedly increased histone acetylation. The in vitro observations were confirmed in an in vivo murine xenograft experiment with the Ly1 DLBCL line. Genome wide methylation analysis and gene expression profiling demonstrated that the combination of these two epigenetic therapies produced a unique gene expression profile compared to the samples treated with single drugs. These data strongly support the potential therapeutic role of a combinatorial epigenetic platform for the treatment of B-cell lymphomas, in particular in patients with DLBCL. Clearly, future studies will need to focus on integrating the appropriate correlative studies, with an effort to identify and or validate biomarkers of activity with these combinations. The likelihood moving forward is that the mechanism of action of these combinations may vary from disease context to disease context. Genome-wide array findings from these kinds of studies could be expanded to samples from patients on clinical trials to identify novel biomarkers of response, leading to the rational treatment of individual diseases based upon the underlying pathogenesis.

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High miR-34a expression improves response to doxorubicin in diffuse large B-cell lymphoma.

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