Treatment induced senescence (TIS) is a terminal cell cycle arrest program, increasingly recognized as a tumor suppressor mechanism complementing apoptosis in response to standard chemotherapy regimens. In particular cells with blocked apoptotic pathways rely on senescence as the only remaining failsafe mechanism to keep the neoplastic growth in check. However, little is known about biological properties, long-term fate of senescent tumor cells and their impact on the microenvironment.
Opposing roles of NF-κB in anti-cancer treatment outcome unveiled by cross-species investigations.
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View SamplesDiffuse large B-cell lymphoma (DLBCL) represents a heterogeneous diagnostic category with distinct molecular subtypes that can be defined by gene expression profiling. However, even within these defined subtypes, heterogeneity prevails. To further elucidate the pathogenesis of these entities, we determined the expression of the tumor suppressor phosphatase and tensin homolog (PTEN) in 248 primary DLBCL patient samples. These analyses revealed that loss of PTEN was detectable in 55% of germinal center B-cell-like (GCB) DLBCLs, whereas this abnormality was found in only 14% of non-GCB DLBCL patient samples. In GCB DLBCL, the PTEN status was inversely correlated with activation of the oncogenic PI3K/ protein kinase B (AKT) pathway in both DLBCL cell lines and primary patient samples. Re-expression of PTEN induced cytotoxicity in PTEN-deficient GCB DLBCL cell line models by inhibiting PI3K/AKT signaling, indicating an addiction to this pathway in this subset of GCB DLBCLs. PI3K/AKT inhibition induced down-regulation of the transcription factor MYC. Re-expression of MYC rescued GCB DLBCL cells from PTEN-induced toxicity, identifying a regulatory mechanism of MYC expression in DLBCL. Finally, pharmacologic PI3K inhibition resulted in toxicity selectively in PTEN-deficient GCB DLBCL lines. Collectively, our results indicate that PTEN loss defines a PI3K/ AKT-dependent GCB DLBCL subtype that is addicted to PI3K and MYC signaling and suggest that pharmacologic inhibition of PI3K might represent a promising therapeutic approach in these lymphomas.
PTEN loss defines a PI3K/AKT pathway-dependent germinal center subtype of diffuse large B-cell lymphoma.
Sex, Disease, Cell line, Treatment
View Samples1,2-unsaturated pyrrolizidine alkaloids (PA) are plant metabolites predominantly occurring in the plant families Asteraceae and Boraginaceae. Acute and chronic PA poisoning causes severe hepatotoxicity. So far, the molecular mechanisms of PA toxicity are not well understood. To analyze its mode of action, primary human hepatocytes were exposed to a non-cytotoxic dose of 100 M of four structurally different PA: echimidine, heliotrine, senecionine, senkirkine. Changes in mRNA expression were analyzed by a whole genome microarray. Employing cut-off values with a |fold change| of 2 and a q-value of 0.01, data analysis revealed numerous changes in gene expression. In total, 4556, 1806, 3406 and 8623 genes were regulated by echimidine, heliotrine, senecione and senkirkine, respectively. 1304 genes were identified as commonly regulated. PA affected pathways related to cell cycle regulation, cell death and cancer development. The transcription factors TP53, MYC, NFB and NUPR1 were predicted to be activated upon PA treatment. Furthermore, gene expression data showed a considerable interference with lipid metabolism and bile acid flow. The associated transcription factors FXR, LXR, SREBF1/2, and PPAR// were predicted to be inhibited. In conclusion, though structurally different, all four PA significantly regulated a great number of genes in common. This proposes similar molecular mechanisms, although the extent seems to differ between the analyzed PA as reflected by the potential hepatotoxicity and individual PA structure.
Disturbance of gene expression in primary human hepatocytes by hepatotoxic pyrrolizidine alkaloids: A whole genome transcriptome analysis.
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View SamplesTumor-induced immunosuppression remains a major challenge for immunotherapy of cancer patients. To further elucidate why an allogeneic gene-modified (Interleukin-7(IL-7)/CD80 co-transfected) renal cell cancer vaccine failed to induce clinically relevant TH1-polarized immune responses, peripheral blood mononuclear cells (PBMCs) from enrolled study patients were analyzed by gene expression profiling (GEP) both prior and after vaccination. At baseline before vaccination, a profound downregulation of gene signatures associated with antigen presentation, immune response/T cells, cytokines/chemokines and signaling/transcription factors was observed in renal cell cancer patients as compared to healthy controls. Vaccination led to a partial reversion of preexisting immunosuppression, however, GEP indicated that an appropriate TH1 polarization could not be achieved. Most interestingly, our results suggest that the nuclear factor kappa B (NF-B) signaling pathway might be involved in the impairment of immunological responsiveness and the observed TH2 deviation. In summary, our data suggest that GEP might be a powerful tool for the prediction of immunosuppression and the monitoring of immune responses within immunotherapy trials.
Gene expression profiling of peripheral blood mononuclear cells during treatment with a gene-modified allogeneic tumor cell vaccine in advanced renal cell cancer: tumor-induced immunosuppression and a possible role for NF-κB.
Treatment
View SamplesConstitutive activation of the anti-apoptotic NF-B signaling pathway is a hallmark of the activated B-cell-like (ABC) subtype of diffuse large B-cell lymphomas (DLBCL) that is characterized by adverse survival. Recurrent oncogenic mutations are found in the scaffold protein CARMA1 (CARD11) that connects B-cell receptor (BCR) signaling to the canonical NF-B pathway. We asked how far additional downstream processes are activated and contribute to the oncogenic potential of DLBCL-derived CARMA1 mutants. To this end, we expressed oncogenic CARMA1 mutants in the NF-B negative DLBCL lymphoma cell line BJAB. By a proteomic approach we identified recruitment of -Catenin and its destruction complex consisting of APC, AXIN1, CK1 and GSK3 to oncogenic CARMA1. Recruitment of the -Catenin destruction complex was independent of CARMA1-BCL10-MALT1 (CBM) complex formation or constitutive NF-B activation and promoted the stabilization of -Catenin. Elevated -Catenin expression was detected in cell lines and biopsies from ABC DLBCL that rely on chronic BCR signaling. Increased -Catenin amounts alone were not sufficient to induce classical WNT target gene signatures, but could augment TCF/LEF dependent transcriptional activation in response to WNT signaling. In conjunction with NF-B, -Catenin enhanced expression of immune suppressive IL-10 and repressed anti-tumoral CCL3, indicating that -Catenin may induce a favorable tumor microenvironment. Thus, parallel activation of NF-B and -Catenin signaling by gain-of-function mutations in CARMA1 can augment WNT stimulation and is required for maintaining high expression of distinct NF-B target genes and can thereby trigger cell intrinsic and extrinsic processes that promote DLBCL lymphomagenesis.
Oncogenic CARMA1 couples NF-κB and β-catenin signaling in diffuse large B-cell lymphomas.
Specimen part, Cell line
View SamplesA unique feature of the tumour cells (Hodgkin/Reed-Sternberg (HRS)) of classical Hodgkin lymphoma (cHL) is the loss of their B-cell phenotype despite their B-cell origin. Several lines of evidence suggest that epigenomic events, especially promoter DNA-methylation, are involved in this silencing of many B-cell associated genes. Here we show that DNA-demethylation alone or in conjunction with histone-acetylation is not able to reconstitute the B-cell gene expression program in cultured HRS cells. Instead, combined DNA-demethylation and histone-acetylation of B cells induce a nearly complete extinction of their B-cell expression program and a tremendous up-regulation of numerous cHL characteristic genes including key players such as Id2 known to be involved in the suppression of the B-cell phenotype. Since the up-regulation of cHL characteristic genes and the extinction of the B-cell expression program occurred simultaneously, epigenetic changes may also be responsible for the malignant transformation of cHL. The epigenetic up-regulation of cHL characteristic genes thus play - in addition to promoter DNA-hypermethylation of B-cell associated genes a pivotal role for the reprogramming of HRS cells and explain why DNA-demethylation alone is unable to reconstitute the B-cell expression program in HRS cells.
Histone acetylation and DNA demethylation of B cells result in a Hodgkin-like phenotype.
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View SamplesMouse erythroid progenitors (EP) in comparison to granulocyte/monocyte - macrophage progenitors (GMP) from 10 - 16 week old C57/Bl6 - S129Ola (mixed genetic background) purified by flow cytometry
Prospective isolation and global gene expression analysis of the erythrocyte colony-forming unit (CFU-E).
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View SamplesA characteristic feature of anaplastic large cell lymphoma (ALCL) is the significant reduction of the T-cell expression program despite its T-cell origin, a finding very similar to the loss of B-cell identity of classical Hodgkin lymphoma (cHL). Previously we demonstrated that epigenetic mechanisms are active in cHL to induce this peculiar phenotype. The results show that combined DNA demethylation and histone acetylation of T-cell lines induce an almost complete extinction of the T-cell phenotype, including the down-regulation of essential T-cell receptor signalling pathway genes such as CD3, LCK and ZAP70, as well as an up-regulation of ALCL-characteristic genes. In contrast, combined DNA demethylation and histone acetylation of ALCL cells is not able to reconstitute their T-cell phenotype. This clearly demonstrates that similar epigenetic mechanisms are active in ALCL and cHL which are responsible for the extinction of their cell type characteristic phenotype.
Histone acetylation and DNA demethylation of T cells result in an anaplastic large cell lymphoma-like phenotype.
Specimen part, Cell line, Treatment
View SamplesIn human chronic lymphocytic leukemia (CLL) pathogenesis B cell antigen receptor signaling seems important for leukemia B cell ontogeny, whereas the microenvironment influences B cell activation, tumor cell lodging and provision of antigenic stimuli. Using the murine E-Tcl1 CLL model, we demonstrate that CXCR5-controlled access to follicular dendritic cells (FDCs) confers proliferative stimuli to leukemia B cells. Intravital imaging revealed a marginal zone B cell-like leukemia cell trafficking route. Murine and human CLL cells reciprocally stimulated resident mesenchymal stromal cells through lymphotoxin--receptor activation, resulting in CXCL13 secretion and stromal compartment remodeling. Inhibition of lymphotoxin/lymphotoxin--receptor signaling or of CXCR5 signaling retards leukemia progression. Thus, CXCR5 activity links tumor cell homing, shaping a survival niche, and access to localized proliferation stimuli.
Access to follicular dendritic cells is a pivotal step in murine chronic lymphocytic leukemia B-cell activation and proliferation.
Specimen part
View SamplesBreakdown products of some glucosinolates defense chemicals of Brassicales induce detoxifying enzymes and demonstrate preventive activities against chemically induced tumorigenesis in animal models. However, other breakdown products are genotoxic. 1-Methoxy-3-indolylmethyl alcohol (1-MIM-OH) is mutagenic in bacterial and mammalian cells upon activation by sulphotransferases and forms DNA adducts in mouse tissues. This effect was enhanced in mice transgenic for human sulphotransferases 1A1/2 (FVB/N-hSULT1A1/2). In this study we explored gene expression changes induced by 1-MIM-OH in mouse liver. FVB/N-hSULT1A1/2 mice were orally treated with 1-MIM-OH for 21 or 90 days, leading to high levels of hepatic 1-MIM-DNA adducts. Genome-wide expression analyzes in this tissue demonstrated no influence on detoxifying enzymes, but up-regulation of many mediators of the tumour suppressor p53 and down-regulation of Fhit and other long genes. In conclusion, 1-MIM-OH did not induce protective enzymes, but formed high levels of DNA adducts, which were recognized by affected cells as reflected by p53 activation. While this p53 response might aim to protection, it was unable to prevent the accumulation of DNA adducts. However, various epdemiological studies reported inverse associations between the intake of cruciferous vegetables and cancer. This association might be due to the presence of other glucosinolates with tumour-preventing influences possibly outweighing adverse effects of some metabolites. Nevertheless, 1-MIM-OH is a genotoxic substance inducing a gene expression profile similar to the expression signature caused by known genotoxic hepatocarcinogens.
The glucosinolate metabolite 1-methoxy-3-indolylmethyl alcohol induces a gene expression profile in mouse liver similar to the expression signature caused by known genotoxic hepatocarcinogens.
Sex, Specimen part, Treatment
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