Project description:We established two representative ABC DLBCL cell lines (TMD8 and OCI-Ly10) with ibrutinib resistance by gradually increasing the concentration of ibrutinib during passage in culture. RNA-seq analysis demonstrated that the BCR pathway gene signature is enriched in resistant cell lines when compared to parental cells. The most upregulated gene is EGR1, a transcription factor that activates multiple oncogenic pathways including MYC and E2F. Elevated EGR1 expression is also observed in ibrutinib-resistant primary mantle cell lymphoma cells when treated with ibrutinib. Using multiple metabolic and genetic approaches, we discovered that overexpression of EGR1 causes metabolic reprogramming to oxidative phosphorylation (OXPHOS) and ibrutinib resistance. Mechanistically, EGR1 mediates metabolic reprogramming through transcriptional activation of PDP1, a phosphatase that dephosphorylates and activates the E1 component of the large pyruvate dehydrogenase complex. Therefore, EGR1-mediated PDP1 activation accelerates intracellular ATP production via the mitochondrial tricarboxylic acid (TCA) cycle, leading to sufficient energy to enhance the proliferation and survival of ibrutinib-resistant lymphoma cells. Finally, we demonstrate that targeting OXPHOS with IM156, a newly developed OXPHOS inhibitor, inhibits the growth of ibrutinib-resistant lymphoma cells both in vitro and in patient-derived xenograft mouse models.
Project description:Ibrutinib,a novel Bruton'styrosine kinase inhibitor, demonstrated high response rates in B-cell lymphomas but a growing number of ibrutinib treated patients relapse with resistance, fulminant progression and accelerated mortality. Using chemical proteomics and a high-throughput ex vivo assay in a reconstructed tumor microenvironment (TME), we determined the molecular basis for ibrutinib activity and mechanism of acquired ibrutinib resistance. Reciprocal activation of PI3K-AKT-mTOR and integrin β1 signaling were identified as a signaling hub of kinome for ibrutinib resistance, resulting in enforced TME-lymphoma interactions, promoting mantle cell lymphoma (MCL) growth and drug resistance. Combinatorial disruption of BCR signaling and ibrutinib resistance associated pathways led to release of MCL cells from TME, reversal of drugresistance and enhanced anti-MCL activity in murine and patient-derived xenograft models. This study integrated TME-mediated de-novo and acquired drug resistance mechanisms and provides the rationale for novel combination therapeutic strategy against MCL and other B cell malignancies.
Project description:The use of Bruton tyrosine kinase (BTK) inhibitors such as ibrutinib has achieved a remarkable clinical response in mantle cell lymphoma (MCL). Acquired drug resistance, however, is significant and impacts long-term survival of MCL patients. Here we demonstrate that DNMT3A is involved in ibrutinib resistance. We found that DNMT3A expression is upregulated upon ibrutinib treatment in ibrutinib-resistant MCL cells. Genetic and pharmacological analyses revealed that DNMT3A mediates ibrutinib resistance independent of its DNA-methylation function. Mechanistically, DNMT3A induces the expression of MYC target genes through interaction with the transcription factors MEF2B and MYC, thus mediating metabolic reprogramming to oxidative phosphorylation (OXPHOS). Targeting DNMT3A by a low dose of decitabine inhibits the growth of ibrutinib-resistant lymphoma cells both in vitro and in a patient-derived xenograft mouse model. These findings suggest that targeting DNMT3A-medited metabolic reprogramming to OXPHOS with decitabine provides a potential therapeutic strategy to overcome ibrutinib resistance in relapsed/refractory MCL.
Project description:Ibrutinib, a bruton's tyrosine kinase inhibitor, was shown to have high response rates in mantle cell lymphoma (MCL), an aggressive B-cell lymphoma. However, emergence of ibrutinib resistance (IR) and subsequent fatal progression is of significant clinical concern. By implementing genomics, chemical proteomics and drug screening, we report that enhancer remodeling-mediated transcriptional activation and adaptive signaling changes drive the malignant phenotype of IR. Accordingly, IR MCL cells are vulnerable to inhibition of the transcriptional machinery and especially to inhibition of cyclin-dependent kinase 9 (CDK9). Thus, targeting transcriptional activation offers a novel strategy to prevent the emergence of IR and overcome IR via impeding IR-associated cellular signaling reprogramming in MCL. In addition, our ex-vivo microfluidic image-based functional drug screen can function not only as new technology platforms for predicting clinical therapeutic response but also, in conjunction with genomic profiling in primary MCL samples, identify the molecular vulnerabilities for drug resistance evolution, providing insight into the underlying IR mechanisms for MCL and other B-cell malignancies
Project description:Mutations in PLCγ, a substrate of the tyrosine kinase BTK, are often found in patients who develop resistance to the BTK inhibitor Ibrutinib. However, the mechanisms by which these PLCγ mutations cause Ibrutinib resistance are unclear. Under normal signaling conditions, BTK mediated phosphorylation of Y783 within the PLCγ cSH2-linker promotes the intramolecular association of this site with the adjacent cSH2 domain resulting in active PLCγ. Thus, the cSH2-linker region in the center of the regulatory gamma specific array (γSA) of PLCγ is a key feature controlling PLCγ activity. Even in the unphosphorylated state this linker exists in a conformational equilibrium between free and bound to the cSH2 domain. The position of this equilibrium is optimized within the properly regulated PLCγ enzyme but may be altered in the context of mutations. We therefore assessed the conformational status of four resistance associated mutations within the PLCγ γSA and find that they each alter the conformational equilibrium of the γSA leading to a shift toward active PLCγ. Interestingly, two distinct modes of mutation induced activation are revealed by this panel of Ibrutinib resistance mutations. These findings, along with the recently determined structure of fully autoinhibited PLCγ, provide new insight into the nature of the conformational change that occurs within the γSA regulatory region to affect PLCγ activation. Improving our mechanistic understanding of how B cell signaling escapes Ibrutinib treatment via mutations in PLCγ will aid in the development of strategies to counter drug resistance.
Project description:Ibrutinib, a bruton's tyrosine kinase inhibitor, was shown to have high response rates in mantle cell lymphoma (MCL), an aggressive B-cell lymphoma. However, emergence of ibrutinib resistance (IR) and subsequent fatal progression is of significant clinical concern. By implementing genomics, chemical proteomics and drug screening, we report that enhancer remodeling-mediated transcriptional activation and adaptive signaling changes drive the malignant phenotype of IR. Accordingly, IR MCL cells are vulnerable to inhibition of the transcriptional machinery and especially to inhibition of cyclin-dependent kinase 9 (CDK9). Thus, targeting transcriptional activation offers a novel strategy to prevent the emergence of IR and overcome IR via impeding IR-associated cellular signaling reprogramming in MCL. In addition, our ex-vivo microfluidic image-based functional drug screen can function not only as new technology platforms for predicting clinical therapeutic response but also, in conjunction with genomic profiling in primary MCL samples, identify the molecular vulnerabilities for drug resistance evolution, providing insight into the underlying IR mechanisms for MCL and other B-cell malignancies
Project description:Ibrutinib, a bruton's tyrosine kinase inhibitor, was shown to have high response rates in mantle cell lymphoma (MCL), an aggressive B-cell lymphoma. However, emergence of ibrutinib resistance (IR) and subsequent fatal progression is of significant clinical concern. By implementing genomics, chemical proteomics and drug screening, we report that enhancer remodeling-mediated transcriptional activation and adaptive signaling changes drive the malignant phenotype of IR. Accordingly, IR MCL cells are vulnerable to inhibition of the transcriptional machinery and especially to inhibition of cyclin-dependent kinase 9 (CDK9). Thus, targeting transcriptional activation offers a novel strategy to prevent the emergence of IR and overcome IR via impeding IR-associated cellular signaling reprogramming in MCL. In addition, our ex-vivo microfluidic image-based functional drug screen can function not only as new technology platforms for predicting clinical therapeutic response but also, in conjunction with genomic profiling in primary MCL samples, identify the molecular vulnerabilities for drug resistance evolution, providing insight into the underlying IR mechanisms for MCL and other B-cell malignancies