Synergistic activity of BET protein antagonist-based combinations in Mantle Cell Lymphoma cells sensitive or resistant to ibrutinib
ABSTRACT: To determine the global transcriptome changes in mantle cell lymphoma cells following treatment with the BET bromodomain antagonist, JQ1 Mantle Cell Lymphoma (MCL) cells exhibit increased B cell receptor and NFkB activities. The BET protein BRD4 is essential for the transcriptional activity of NFkB. Here, we demonstrate that treatment with the BET protein bromodomain antagonist (BA) JQ1 attenuates MYC and CDK4/6, inhibits the nuclear RelA levels and the expression of NFκB target genes including Bruton’s Tyrosine Kinase (BTK) in MCL cells. While lowering the levels of the anti-apoptotic BCL2 family proteins, BA treatment induces the pro-apoptotic protein BIM and exerts dose-dependent lethality against cultured and primary MCL cells. Co-treatment with BA and the BTK inhibitor ibrutinib synergistically induces apoptosis of MCL cells. Compared to each agent alone, co-treatment with BA and ibrutinib markedly improved the median survival of mice engrafted with the MCL cells. BA treatment also induced apoptosis of the in vitro isolated, ibrutinib-resistant MCL cells which overexpress CDK6, BCL2, Bcl-xL, XIAP and AKT, but lack ibrutinib resistance-conferring BTK mutation. Co-treatment with BA and panobinostat (pan-histone deacetylase inhibitor) or palbociclib (CDK4/6 inhibitor) or ABT-199 (BCL2 antagonist) synergistically induced apoptosis of the ibrutinib-resistant MCL cells. These findings highlight and support further in vivo evaluation of the efficacy of the BA-based combinations with these agents against MCL, including ibrutinib-resistant MCL. MO2058 cells treated with vehicle, 250 nM or 1000 nM JQ1 for 8 hours. Samples were acquired and analyzed in duplicate.
Project description:The BET (bromodomain and extra terminal) protein family members including BRD4 bind to acetylated lysines on histones and regulate the expression of important oncogenes, e.g., MYC and BCL2. Here we demonstrate the sensitizing effects of the histone hyperacetylation inducing pan-histone deacetylase inhibitor (HDI) panobinostat (PS) on human AML blast progenitor cells (BPCs) to the BET protein inhibitor JQ1. Treatment with JQ1 but not its inactive enantiomer (R-JQ1) was highly lethal against AML BPCs expressing mutant NPM1c+ with or without co-expression of FLT3-ITD, or AML expressing MLL fusion oncoprotein. JQ1 treatment reduced binding of BRD4 and RNA polymerase II to the DNA of MYC and BCL2, and reduced their levels in the AML cells. Co-treatment with JQ1 and the HDAC inhibitor panobinostat (PS) synergistically induced apoptosis of the AML BPCs, but not of normal CD34+ hematopoietic progenitor cells. This was associated with greater attenuation of MYC and BCL2, while increasing p21, BIM and cleaved PARP levels in the AML BPCs. Co-treatment with JQ1 and PS significantly improved the survival of the NOD/SCID mice engrafted with OCI-AML3 or MOLM13 cells (p < 0.01). These findings highlight co-treatment with a BRD4 antagonist and an HDI as a potentially efficacious therapy of AML. Two samples were analyzed (untreated cells, cells treated with JQ1)
Project description:The covalent Bruton’s Tyrosine Kinase (BTK) inhibitor ibrutinib is highly efficacious against multiple B-cell malignancies. However, it also has off-target effects and multiple mechanisms of resistance, including the C481S mutation. We hypothesized that small molecule-induced BTK degradation might be able to overcome some of the limitations of traditional enzymatic inhibitors. Here, we demonstrate that BTK degradation results in more durable suppression of signaling and proliferation in cancer cells than BTK inhibition and that BTK degraders are able to efficiently degrade BTK C481S. Moreover, we generated DD-03-171, an optimized lead compound that exhibits enhanced anti-proliferative effects on mantle cell lymphoma (MCL) cells in vitro as well as efficacy in a patient-derived xenograft model of MCL. These data suggest that targeted BTK degradation is an effective therapeutic approach in treating MCL and overcoming ibrutinib resistance, thereby addressing a major unmet need in the treatment of MCL and other B-cell lymphomas.
Project description:Diffuse large B-cell lymphoma (DLBCL) and follicular lymphoma (FL) are the most prevalent B-lymphocyte neoplasms in which abnormal activation of the Bruton’s tyrosine kinase (BTK)–mediated B-cell receptor (BCR) signaling pathway contributes to pathogenesis. Ibrutinib is an oral covalent BTK inhibitor that has shown some efficacy in both indications. To improve ibrutinib efficacy through combination therapy, we first investigated differential gene expression in parental and ibrutinib-resistant cell lines to better understand the mechanisms of resistance. Ibrutinib-resistant TMD8 cells had higher BCL2 gene expression and increased sensitivity to ABT-199, a BCL-2 inhibitor. Consistently, clinical samples from ABC-DLBCL patients who experienced poorer response to ibrutinib had higher BCL2 gene expression. We further demonstrated synergistic growth suppression by ibrutinib and ABT-199 in multiple ABC-DLBCL, GCB-DLBCL, and FL lymphoma cell lines. The combination of both drugs also reduced colony formation, increased apoptosis, and inhibited tumor growth in a TMD8 xenograft model. A synergistic combination effect was also found in ibrutinib-resistant cells generated by either genetic mutation or drug treatment. Together, these findings suggest a potential clinical benefit from ibrutinib and ABT-199 combination therapy. Overall design: Gene expression in parental or ibrutinib-resistant TMD8 cells was detected by HTA2.0 arrays and the level of BCL2 expression was compared between these two groups.
Project description:MCL cell lines were treated with DMSO or 5uM AFN700 for 20hrs This experiment is designed to see if NFKB-target genes are downregulated by inhibition of IKKB in MCL cell lines that are insensitive to ibrutinib (BTK inhibitor) or sotrastaurin (PKC inhibitor) MCL cells were seeded in 6well dishes and treated for 20hrs with DMSO or 5uM AFN700
Project description:In the activated B cell-like (ABC) subtype of diffuse large B cell lymphoma (DLBCL), NF-kappaB activity is essential for viability of the malignant cells and is sustained by constitutive activity of IkappaB kinase (IKK) in the cytoplasm. Here, we report an unexpected role for the bromodomain and extraterminal domain (BET) proteins BRD2 and BRD4 in maintaining oncogenic IKK activity in ABC DLBCL. IKK activity was reduced by small molecules targeting BET proteins as well as by genetic knockdown of BRD2 and BRD4 expression, thereby inhibiting downstream NF-kappaB-driven transcriptional programs and killing ABC DLBCL cells. Using a high-throughput platform to screen for drug-drug synergy, we observed that the BET inhibitor JQ1 combined favorably with multiple drugs targeting B cell receptor signaling, one pathway that activates IKK in ABC DLBCL. The BTK kinase inhibitor ibrutinib, which is in clinical development for the treatment of ABC DLBCL, synergized strongly with BET inhibitors in killing ABC DLBCL cells in vitro and in a xenograft mouse model. These findings provide a mechanistic basis for the clinical development of BET protein inhibitors in ABC DLBCL, particularly in combination with other modulators of oncogenic IKK signaling. For JQ1 time course gene expression profiling, HBL1 and LP1 cells were treated with either DMSO or 100nM JQ1 for 1h, 3h, 8h, and 24h. For shRNA gene expression profiling, HBL1 cells were infected with either a Ctrl shRNA or with shRNA targeting BRD2 or BRD4. Following puromycin selection, shRNA expression was induced for 1 day and 2 days.
Project description:Diffuse large B-cell lymphoma (DLBCL) and follicular lymphoma (FL) are the most prevalent B-lymphocyte neoplasms in which abnormal activation of the Bruton’s tyrosine kinase (BTK)–mediated B-cell receptor (BCR) signaling pathway contributes to pathogenesis. Ibrutinib is an oral covalent BTK inhibitor that has shown some efficacy in both indications. To improve ibrutinib efficacy through combination therapy, we first investigated differential gene expression in parental and ibrutinib-resistant cell lines to better understand the mechanisms of resistance. Ibrutinib-resistant TMD8 cells had higher BCL2 gene expression and increased sensitivity to ABT-199, a BCL-2 inhibitor. Consistently, clinical samples from ABC-DLBCL patients who experienced poorer response to ibrutinib had higher BCL2 gene expression. We further demonstrated synergistic growth suppression by ibrutinib and ABT-199 in multiple ABC-DLBCL, GCB-DLBCL, and FL lymphoma cell lines. The combination of both drugs also reduced colony formation, increased apoptosis, and inhibited tumor growth in a TMD8 xenograft model. A synergistic combination effect was also found in ibrutinib-resistant cells generated by either genetic mutation or drug treatment. Together, these findings suggest a potential clinical benefit from ibrutinib and ABT-199 combination therapy. Overall design: Gene expression in ibrutinib pretreated tumor biopsy samples from ABC-DLBCL patients was detected by U133 plus 2.0 arrays and the correlation of BCL2 expression and patient response to ibrutinib or PFS after ibrutinib treatment was analyzed. There are total 28 ABC-DLBCL samples. 17 of them are non-responders (PD+SD) and 11 of them are responders (PR+CR). For this analysis restricted to ABC-DLBCL subtype, only the ABC-DLBCL samples were used and normalized separately. Data was processed with all subsets of DLBCL samples (60 samples) and also separately for 28 ABC-DLBCL samples ('re-analysis' samples). The values in the sample 'characteristics' field represent: response: CR=complete response, PR=partial response, SD=stable disease, PD=progression disease class: NR=non-responder, RR=responder subtype: ABC=ABC-DLBCL, GCB=GCB-DLBCL, UNC=unclassified subtype progression_free_survival_censor: censored case = 1; event (death/progression) = 0 in the censoring variable for the progression free survival analysis
Project description:Chronic lymphocytic leukaemia (CLL) is the most common haematological malignancy in developed countries. Ibrutinib (PCI-32765), a specific and irreversible inhibitor of Bruton's Tyrosine Kinase (BTK) represents a major step forward in the treatment of CLL. We have undertaken a detailed analysis of the changes happening to the chromatin structure in CLL cells from patients continuously receiving oral doses of ibrutinib. ChIP-seq has been performed for H3K4me3, H3K27ac, H3K27me3 and EZH2 up to 56 days following the beginning of the treatment. We observed that Ibrutinib-dependent lymphocytosis correlates with a global and transient recruitment of EZH2 to active cis-regulatory elements and increased H3K27me3.
Project description:We analyzed the transcriptional consequences of the BET bromodomain inhibitor JQ1 in the T-ALL cell line LOUCY by microarray analysis. Sustained exposure at a high concentration (48h, 1µM) revealed broad transcriptional effects with more than half of the expressed probesets showing significant up- or downregulation (adj. p-value<0.05). Significantly downregulated genes included stem-cell associated genes and putative oncogenes such as BAALC, WT1, MN1, MEF2C, LMO1, LMO2, BCL2, IGFBP7, ZEB2, GFI1B, MYB and LYL1. Overall design: LOUCY cells were treated with 1µM (+)-JQ1 or DMSO for 48h. Three biological replicates of this treatment were performed.
Project description:By using a unique functional protein microarray platform, we found that the FDA approved drug ibrutinib can inhibits ERBB4 activity in the same nM range as its canonical target, BTK. Cell-based assays revealed that ibrutinib treatment inhibited cell growth in some ERBB4 expressing cancer cells whereas no response was observed in other cells. Therefore, to identify global gene expression differences between ibrutinib responsive and non-responsive cancer cells, we performed RNA-Seq, and identified a signature featuring the WNT pathway that predicts growth responsiveness to ibrutinib in ERBB4 expressing cancers. Overall design: Examination of gene expression profiles of 4 ibrutinib responsive and 4 ibrutinib non-responsive ERBB4 expressing cancer cell lines
Project description:We provide direct in vivo evidence for activation of the BCR and canonical NF-KB pathways in MCL that, in the absence of activating mutations, is dependent on the lymph node microenvironment. This finding provides a mechanistic explanation for the surprising efficacy of ibrutinib for the treatment of this type of lymphoma. Mutations in components of the BCR and NF-KB pathways are associated with cell-autonomous signaling and resistance to ibrutinib. Lymph node biopsies and peripheral blood samples were obtained from patients with previously untreated MCL.