Project description:Runt-related transcription factor 3 (RUNX3) has been described as a tumor suppressor for gastric cancer and other solid malignancies. Despite its key role in physiological T-cell differentiation, there is rare information on its relevance for the development of human T-cell lymphoma or leukemia. Here we show that alterations of RUNX3 by either heterozygous deletion or methylation of its distal promoter can be observed in the tumor cells of 15/21 (71%) patients suffering from Sézary Syndrome (SS), an aggressive variant of cutaneous T-cell lymphoma. In consequence, mRNA levels of RUNX3/p46, the long isoform of RUNX3 – controlled by the proximal promoter – are significantly lower in SS tumor cells. Re-expression of RUNX3/p46 promotes apoptosis and slows down proliferation in a RUNX3/p46low cell line of cutaneous T-cell lymphoma. By this we present the first evidence that RUNX3 can act as a tumor suppressor in a human T-cell malignancy and suggest that this effect is predominantly mediated through the long isoform of this transcription factor, which has not been in the focus of previous studies.
Project description:To identify key tumour supressor miRNAs involed in MALT lymphoma pathogenesis Gastric mucosa-associated lymphoid tissue lymphoma develops in the chronically inflamed mucosa of Helicobacter pylori-infected patients. MicroRNA expression profiling of human MALT lymphoma revealed a 10-fold down-regulation of miR-203, which resulted from promoter hypermethylation and coincided with the dysregulation of the miR-203 target ABL1. Demethylating treatment of lymphoma B-cells led to an increase in miR-203 expression and concomitant ABL1 down-regulation. The lentiviral delivery of miR-203, as well as treatment with various ABL inhibitors, prevented primary MALT lymphoma cell proliferation in vitro. Finally, the treatment of tumor-bearing mice with imatinib induced MALT lymphoma regression in vivo. Our results show that MALT lymphomagenesis is epigenetically induced by miR-203 promoter methylation and identify ABL1 as a novel target for the treatment of this malignancy. 5 human fresh frozen MALT lymphoma samples were analysed and 4 human tonsil tissue samples were used as the non-tumour control
Project description:To identify key tumour supressor miRNAs involed in MALT lymphoma pathogenesis Gastric mucosa-associated lymphoid tissue lymphoma develops in the chronically inflamed mucosa of Helicobacter pylori-infected patients. MicroRNA expression profiling of human MALT lymphoma revealed a 10-fold down-regulation of miR-203, which resulted from promoter hypermethylation and coincided with the dysregulation of the miR-203 target ABL1. Demethylating treatment of lymphoma B-cells led to an increase in miR-203 expression and concomitant ABL1 down-regulation. The lentiviral delivery of miR-203, as well as treatment with various ABL inhibitors, prevented primary MALT lymphoma cell proliferation in vitro. Finally, the treatment of tumor-bearing mice with imatinib induced MALT lymphoma regression in vivo. Our results show that MALT lymphomagenesis is epigenetically induced by miR-203 promoter methylation and identify ABL1 as a novel target for the treatment of this malignancy.
Project description:Cancer-associated fibroblasts (CAFs) are a major stromal component of human breast cancers and often promote tumor proliferation, progression and malignancy. We previously established an experimental CAF (exp-CAF) cell line equipped with a potent tumor-promoting ability. It was generated through prolonged incubation of immortalized human mammary fibroblasts with human breast cancer cells in a tumor xenograft mouse model. Herein, we found that the exp-CAFs highly express Runt-related transcription factor 3 (RUNX3), while counterpart fibroblasts do not. In breast cancer patients, the proportion of RUNX3-positive stromal fibroblast-like cells tends to be higher in cancerous regions than in non-cancerous regions. These findings suggest an association of RUNX3 with CAF characteristics in human breast cancers. To investigate the functional role of RUNX3 in CAFs, the exp-CAFs with or without shRNA-directed knockdown of RUNX3 were implanted with breast cancer cells subcutaneously in immunodeficient mice. Comparison of the resulting xenograft tumors revealed that tumor growth was significantly attenuated when RUNX3 expression was suppressed in the fibroblasts. Consistently, Ki-67 and CD31 immunohistochemical staining of the tumor sections indicated reduction of cancer cell proliferation and microvessel formation in the tumors formed with the RUNX3-suppressed exp-CAFs. These results suggest that increased RUNX3 expression could contribute to the tumor-promoting ability of CAFs through mediating cancer cell growth and neoangiogenesis in human breast tumors.
Project description:Ewing sarcoma is an aggressive pediatric small round cell tumor that predominantly occurs in bone. Approximately 85% of Ewing sarcomas harbor the EWS/FLI fusion protein, which arises from a chromosomal translocation, t(11:22)(q24:q12). EWS/FLI interacts with numerous lineage-essential transcription factors to maintain mesenchymal progenitors in an undifferentiated state. We previously showed that EWS/FLI binds the osteogenic transcription factor RUNX2 and prevents osteoblast differentiation. In this study, we investigated the role of another Runt-domain protein, RUNX3, in Ewing sarcoma. RUNX3 participates in mesenchymal-derived bone formation and is a context dependent tumor suppressor and oncogene. RUNX3 was detected in all Ewing sarcoma cells examined, whereas RUNX2 was detected in only 73% of specimens. Like RUNX2, RUNX3 binds to EWS/FLI via its Runt domain. EWS/FLI prevented RUNX3 from activating the transcription of a RUNX-responsive reporter, p6OSE2. Stable suppression of RUNX3 expression in the Ewing sarcoma cell line A673 delayed colony growth in anchorage independent soft agar assays and reversed expression of EWS/FLI-responsive genes. These results demonstrate an important role for RUNX3 in Ewing sarcoma. RNA-seq to compare transcriptiome of control A673 ewing sarcoma cells stably expression a non-target or RUNX3 shRNA
Project description:Two long and one truncated isoforms (termed LAP*, LAP, and LIP, respectively) of the transcription factor CCAAT enhancer binding protein beta (C/EBPM-NM-2) are expressed from a single intronless Cebpb gene by alternative translation initiation. Isoform expression is sensitive to mammalian target of rapamycin (mTOR)-mediated activation of the translation initiation machinery and relayed through an upstream open reading frame (uORF) on the C/EBPM-NM-2 mRNA. The truncated C/EBPM-NM-2 LIP, initiated by high mTOR activity, has been implied in neoplasia, but it was never shown whether endogenous C/EBPM-NM-2 LIP may function as an oncogene. In this study, we examined spontaneous tumor formation in C/EBPM-NM-2 knockin mice that constitutively express only the C/EBPM-NM-2 LIP isoform from its own locus. Our data show that deregulated C/EBPM-NM-2 LIP predisposes to oncogenesis in many tissues. Gene expression profiling suggests that C/EBPM-NM-2 LIP supports a protumorigenic microenvironment, resistance to apoptosis, and alteration of cytokine/chemokine expression. The results imply that enhanced translation reinitiation of C/ EBPM-NM-2 LIP promotes tumorigenesis. Accordingly, pharmacological restriction of mTOR function might be a therapeutic option in tumorigenesis that involves enhanced expression of the truncated C/EBPM-NM-2 LIP isoform. A cohort of C/EBPb LIP heterozygous (+/L) and wild type (+/+) mice were kept over 25 months and animals showing palpable lymphoma were sacrificed. The lymphoma developed spontaneously. For each genotype, 5 lymphoma were used for RNA preparation and gene expression profiling analysis.
Project description:Normal cell growth is characterized by a regulated epigenetic program that drives cellular activities such as gene transcription, DNA replication and DNA damage repair. Perturbation of this epigenetic program can lead to events such as mis-regulation of gene transcription and diseases such as cancer. To begin to understand the epigenetic program correlated to the development of melanoma, we performed a quantitative mass spectrometric analysis of histone posttranslational modifications mis-regulated in melanoma cell culture. Aggressive melanoma cells were found to have elevated histone H3 lysine 27 trimethylation (H3K27me3) as well as over-expressed methyltransferase EZH2 that adds the specific modification. The altered epigenetic program that led to elevated H3K27me3 in melanoma cell culture was found to directly silence transcription of the tumor suppressor gene RUNX3. The elevated level of H3K27me3 and silencing of RUNX3 transcription was also validated in advanced stage human melanoma tissues. The study presented underscores the utility of using high resolution mass spectrometry to identify mis-regulated epigenetic programs in diseases such as cancer, which could ultimately lead to the identification of biological markers for diagnostic and prognostic applications.