Mantle cell lymphoma (MCL) is a mature B-cell lymphoma characterized by poor clinical outcome. Recent studies revealed the importance of B-cell receptor (BCR) signaling in maintaining MCL survival. However, it remains unclear which role MALT1, an essential component of the CARD11-BCL10-MALT1 complex that links BCR signaling to the NF-κB pathway, plays in the biology of MCL. Here we show that a subset of MCLs is addicted to MALT1, as its inhibition by either RNA or pharmacologic interference induced cytotoxicity both in vitro and in vivo. Gene expression profiling following MALT1 inhibition demonstrated that MALT1 controls an MYC-driven gene expression network predominantly through increasing MYC protein stability. Thus, our analyses identify a previously unappreciated regulatory mechanism of MYC expression. Investigating primary mouse splenocytes, we could demonstrate that MALT1-induced MYC regulation is not restricted to MCL, but represents a common mechanism. MYC itself is pivotal for MCL survival because its downregulation and pharmacologic inhibition induced cytotoxicity in all MCL models. Collectively, these results provide a strong mechanistic rationale to investigate the therapeutic efficacy of targeting the MALT1-MYC axis in MCL patients.
- MeSH
- buněčná smrt MeSH
- heterografty MeSH
- kaspasy metabolismus fyziologie MeSH
- lidé MeSH
- lymfom z plášťových buněk metabolismus MeSH
- myši MeSH
- nádorové buněčné linie MeSH
- nádorové proteiny metabolismus fyziologie MeSH
- NF-kappa B metabolismus MeSH
- protein MALT1 MeSH
- protoonkogenní proteiny c-myc metabolismus MeSH
- receptory antigenů B-buněk fyziologie MeSH
- regulace genové exprese u nádorů MeSH
- signální transdukce MeSH
- viabilita buněk MeSH
- zvířata MeSH
- Check Tag
- lidé MeSH
- myši MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Richter syndrome represents the transformation of the chronic lymphocytic leukemia (CLL) into an aggressive lymphoma, most frequently the diffuse large B-cell lymphoma (DLBCL). In this report we describe a patient with CLL, who developed a clonally-related pleomorphic highly-aggressive mantle cell lymphoma (MCL) after five cycles of a fludarabine-based second-line therapy for the first relapse of CLL. Molecular cytogenetic methods together with whole-exome sequencing revealed numerous gene alterations restricted to the MCL clone (apart from the canonical t(11;14)(q13;q32) translocation) including gain of one copy of ATM gene or emergence of TP53, CREBBP, NUP214, FUBP1 and SF3B1 gene mutations. Similarly, gene expression analysis revealed vast differences between the MCL and CLL transcriptome, including overexpression of cyclin D1, downregulation of cyclins D2 and D3, or downregulation of IL4R in the MCL clone. Backtracking analysis using quantitative PCR specifically detecting an MCL-restricted focal deletion of TP53 revealed that the pre-MCL clone appeared in the bone marrow and peripheral blood of the patient approximately 4 years before the clinical manifestation of MCL. Both molecular cytogenetic and sequencing data support the hypothesis of a slow development of the pre-MCL clone in parallel to CLL over several years, and thereby exclude the possibility that the transformation event occurred at the stage of the CLL relapse clone by mere t(11;14)(q13;q32) acquisition.
- MeSH
- chronická lymfatická leukemie genetika metabolismus patologie MeSH
- difúzní velkobuněčný B-lymfom genetika metabolismus patologie MeSH
- hybridizace in situ fluorescenční MeSH
- imunohistochemie MeSH
- lidé středního věku MeSH
- lidé MeSH
- lidské chromozomy, pár 11 MeSH
- lidské chromozomy, pár 14 MeSH
- lymfom z plášťových buněk genetika metabolismus patologie MeSH
- nádorové biomarkery genetika metabolismus MeSH
- nádorový supresorový protein p53 genetika metabolismus MeSH
- translokace genetická MeSH
- ztráta heterozygozity MeSH
- Check Tag
- lidé středního věku MeSH
- lidé MeSH
- ženské pohlaví MeSH
- Publikační typ
- časopisecké články MeSH
- kazuistiky MeSH
