Project description:We show that the RNA-binding protein CSDE1/UNR promotes oncogene-induced senescence (OIS) in primary mouse keratynocytes challenged by over-expression of H-RASv12. Depletion of CSDE1 leads to senescence bypass, cell immortalization and tumor formation. Combining individual nucleotide cross-linking and immunoprecipitation (iCLIP), RNA-seq and polysome profiling followed by functional studies, we identify targets regulated by CSDE1 and uncover the downstream molecular mechanisms.
Project description:We show that the RNA-binding protein CSDE1/UNR promotes oncogene-induced senescence (OIS) in primary mouse keratynocytes challenged by over-expression of H-RASv12. Depletion of CSDE1 leads to senescence bypass, cell immortalization and tumor formation. Combining individual nucleotide cross-linking and immunoprecipitation (iCLIP), RNA-seq and polysome profiling followed by functional studies, we identify targets regulated by CSDE1 and uncover the downstream molecular mechanisms.
Project description:We show that the RNA-binding protein CSDE1/UNR promotes oncogene-induced senescence (OIS) in primary mouse keratynocytes challenged by over-expression of H-RASv12. Depletion of CSDE1 leads to senescence bypass, cell immortalization and tumor formation. Combining individual nucleotide cross-linking and immunoprecipitation (iCLIP), RNA-seq and polysome profiling followed by functional studies, we identify targets regulated by CSDE1 and uncover the downstream molecular mechanisms.
Project description:We show that the RNA-binding protein CSDE1/UNR promotes oncogene-induced senescence (OIS) in primary mouse keratynocytes challenged by over-expression of H-RASv12. Depletion of CSDE1 leads to senescence bypass, cell immortalization and tumor formation. Combining individual nucleotide cross-linking and immunoprecipitation (iCLIP), RNA-seq and polysome profiling followed by functional studies, we identify targets regulated by CSDE1 and uncover the downstream molecular mechanisms.
Project description:Interferon regulatory factor 4 (IRF4) is a transcriptional regulator with critical roles in the normal development and malignant transformation of lymphocytes. Recently we have shown that plasma cell cancers (multiple myeloma, MM) are addicted to an aberrant gene expression program ochestrated by wild-type IRF4 for their survival. Here we show that an aggressive malignancy of mature B cells, the activated B cell for of Diffuse Large B Cell lymphoma (ABC-DLBC), also depends on IRF4 for survival. With genome-wide expression profiling and localization (ChIP-Seq) assays, we identified IRF4 target genes in ABC-DLBCL as members of diverse pathways related to B cell biology and malignant behavior, distinct from IRF4 targets in MM. For example, we find the gene encoding the NFkB signal transduction adapter protein CARD11 is a target of IRF4 activation, driving the critical NFkB pathway in ABC-DLBCL. Further, we find enrichment of DNA binding motifs for ETS-IRF factors in regions of IRF4 binding in ABC-DLBCL suggesting cooperative activity between IRF4 and an ETS family transcription factor. Through complementation assays we show that IRF4 and the critical ABC-DLBCL ETS factor SPIB interact with one another and are key to ABC-DLBCL survival. Together our data show that ABC-DLBCL is addicted to the interaction between IRF4 and SPIB, in part through a positive feedback loop invovling CARD11 and the activation of the NFkB pathway. These data suggest theraepeutic potential in targeting the IRF4:SPIB interface in ABC-DLBCL. Gene expression was analyzed using Agilent human 4X44K oligo gene expression arrays. Cell lines (HBL1, OCILY3, TMD8-ABC-DLBCL; KMS12-MM) were infected with control (shControl, Cy3) or shIRF4_3'UTR (Cy5) constructs, and changes in gene expression were monitored over time after induction of the shRNA with doxycyclin. For each of the three ABC-DLBCL cell line a four timepoint series (24, 48, 72, 96 hrs) of shRNA induction was analyzed, for a total of 12 arrays. In HBL-1 a second shRNA targeting the IRF4 cds (shIRF4_cds) was used in a similar time course of shRNA induction (4 arrays). For the KMS12 MM cell line a three point time course was analyzed using the shIRF4_3'UTR with one technical (using the same RNA sample) duplicate time point measurement (4 arrays). ChIP-Seq data not provided.
Project description:Burkitt lymphoma (BL) can often be cured by intensive chemotherapy, but the toxicity of such therapy precludes its use in the elderly and in patients with endemic BL (eBL) in developing countries, necessitating new strategies. The normal germinal center B cell is the presumed cell of origin for both BL and diffuse large B cell lymphoma (DLBCL), yet gene expression analysis suggests that these malignancies may utilize different oncogenic pathways. BL is subdivided into a sporadic subtype (sBL) that is diagnosed in developed countries, the EBV-associated eBL subtype, and an HIV-associated subtype (hivBL), but it is unclear whether these subtypes employ similar or divergent oncogenic mechanisms. Here we used high throughput RNA sequencing and RNA interference screening to discover essential regulatory pathways that cooperate with MYC, the defining oncogene of this cancer. In 70% of sBL cases, mutations affecting the transcription factor TCF3 (E2A) or its negative regulator ID3 fostered TCF3 dependency. TCF3 activated the pro-survival PI(3) kinase pathway in BL, in part by augmenting tonic B cell receptor signaling. In 38% of sBL cases, oncogenic CCND3 mutations produced highly stable cyclin D3 isoforms that drive cell cycle progression. These findings suggest opportunities to improve therapy for patients with BL. Gene expression was analyzed using Agilent human 4X44K oligo gene expression arrays. Cell lines (Namalwa, BL41, Daudi, Defauw, and THOMAS) were infected with control (empty vector, Cy3) paired with ID3 (Cy5) or control (shControl, Cy3) paired with shTCF3 (Cy5) constructs, and changes in gene expression were monitored over time after induction of the constructs with doxycyclin. In Namalwa (n=8) and THOMAS (n=4) cell lines, a four timepoint series (24, 48, 72, 96 hours) of construct induction was analyzed, for a total of 12 arrays. In BL41 (n=4), Daudi (n=4) and Defauw (n=4) cell lines, a two timepoint series (24 and 48 hours) of construct induction was analyzed, for a total of 12 arrays. In addition, two cell lines (Daudi and THOMAS) were treated with Rapamycin (100 pM) and paired with a DMSO control in a four timepoint series (3, 6, 12 and 24 hours) for a total of 8 arrays.
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.