n4-(2-2-dimethyl-3-oxo-4h-pyrid(1-4)oxazin-6-yl)-5-fluoro-n2-(3-4-5-trimethoxyphenyl)-2-4-pyrimidinediamine and Lymphoma--Mantle-Cell

Mantle cell lymphoma (MCL) is a B cell malignancy characterized by aberrant expression of cyclin D1 due to a t(11;14) translocation. MCL is refractory to conventional chemotherapy, and treatment remains challenging. We investigated the efficacy of the histone deacetylase (HDAC) inhibitor vorinostat combined with one of several B-cell receptor (BCR) signaling inhibitors on MCL cell death and the underlying mechanisms, using MCL cell lines. The Bruton's tyrosine kinase inhibitor PCI-32765 and the spleen tyrosine kinase inhibitor R406 showed synergistic effects with vorinostat on growth inhibition. Treatment with PCI-32765 or R406 alone induced 27.3 ± 2.1 or 25.1 ± 3.2% apoptosis. When combined with vorinostat, these apoptotic fractions significantly increased to 50.8 ± 4.9 and 63.1 ± 5.0%, respectively. Activation of caspase-3 and poly-(ADP-ribose) polymerase cleavage were markedly increased. We performed gene expression profiling following treatment with the combination of vorinostat and individual BCR signaling inhibitors using a microarray, and differentially expressed genes were identified. Kyoto Encyclopedia of Genes and Genomes pathway enrichment analysis showed that the nuclear factor (NF)-κB signaling pathway was significantly enriched following treatment with the combination of vorinostat and R406. Protein expression analysis confirmed the down-regulation of NF-κB1/p105 and cyclin D1, suggesting inhibition of the NF-κB pathway. Taken together, the combination of an HDAC inhibitor and a BCR signaling inhibitor may be a novel therapeutic strategy for MCL.

Topics: Adenine; Apoptosis; Caspases; Cell Line, Tumor; Cyclin D1; Drug Synergism; Histone Deacetylase Inhibitors; Humans; Hydroxamic Acids; Lymphoma, Mantle-Cell; NF-kappa B; Oxazines; Piperidines; Protein Kinase Inhibitors; Pyrazoles; Pyridines; Pyrimidines; Receptors, Antigen, B-Cell; Vorinostat

In B-non-Hodgkin lymphomas, Lyn and Cbp/PAG constitute the core of an oncogenic signalosome that captures the Phosphatidylinositol-3-kinase, the Spleen tyrosine kinase and the Signal transducer and activator of transcription-3 to generate pro-survival and proliferative signals. Lymphoma lines corresponding to follicular, mantle-cell and Burkitt-derived lymphomas display type-specific signalosome organizations that differentially activate PI3K, Syk and STAT3. In the follicular lymphoma line, PI3K, Syk and STAT3 were optimally activated upon association with the Lyn-Cbp/PAG signalosome, while in the Burkitt lymphoma-derived line, the association with Cbp/PAG and activation of PI3K were interfered with by the latent membrane proteins encoded by the Epstein-Barr virus. In the Jeko-1 mantle-cell line, a weak association of Syk with the Lyn-Cbp/PAG signalosome resulted in poor activation of Syk, but in those cells, as in the follicular and Burkitt-derived lines, efficient apoptosis induction by the Syk inhibitor R406 indicated that Syk is nonetheless an important prosurvival element and therefore a valuable therapeutic target. In all configurations described herein is the Lyn-Cbp/PAG signalosome independent of external signals and provides efficient means of activation for its associated lipid and protein kinases. In follicular and Burkitt-derived lines, Syk appears to be activated following binding to Cbp/PAG and no longer requires B-cell receptor-associated activation motifs for activation. Assessment of the different modalities of Lyn-Cbp/PAG signalosome organization could help in selecting the appropriate combination of kinase inhibitors to eliminate a particular type of lymphoma cells.

Topics: Apoptosis; B-Lymphocytes; Burkitt Lymphoma; Cell Line, Tumor; Enzyme Activation; Herpesvirus 4, Human; Humans; Intracellular Signaling Peptides and Proteins; Lymphoma, B-Cell; Lymphoma, Follicular; Lymphoma, Mantle-Cell; Lymphoma, Non-Hodgkin; Membrane Proteins; Oxazines; Phosphatidylinositol 3-Kinases; Protein-Tyrosine Kinases; Pyridines; Signal Transduction; src-Family Kinases; STAT3 Transcription Factor; Syk Kinase