Project description:The RUNX genes encode for transcription factors involved in development and human disease. RUNX1 and RUNX3 are frequently associated with leukemias, yet the basis for their involvement in leukemogenesis is not fully understood. Here we show that Runx1;Runx3 double knockout (DKO) mice exhibited lethal phenotypes due to bone marrow failure and myeloproliferative disorder. These contradictory clinical manifestations are reminiscent of human inherited bone marrow failure syndromes like Fanconi anemia (FA), caused by defective DNA repair. Indeed, Runx1;Runx3 DKO cells showed mitomycin C hypersensitivity, due to impairment of monoubiquitinated-FANCD2 recruitment to DNA damage foci, although FANCD2 monoubiquitination in the FA pathway was unaffected. RUNX1 and RUNX3 interact with FANCD2 independent of CBFM-NM-2, suggesting non-transcriptional role for RUNX in DNA repair. These findings suggest that RUNX dysfunction causes DNA repair defect, besides transcriptional misregulation, and promotes development of leukemias and other cancers. 6 mice were analyzed in this study. 3 Runx1;Runx3 double knockout cKit+Sca1+Lin- hematopoietic stem/progenitor cells were compared with their wild type littermate controls. RNA was isolated from 3 independent Runx1;Runx3 WT KSL samples, each pooled from 3 Runx1;Runx3 WT mice, and 3 independent Runx1;Runx3 DKO KSL samples, using the RNeasy Micro Kit (QIAgen). RNA integrity and quantity was assessed using the Agilent 2000 Bioanalyzer system. 3 M-NM-<g to 5 M-NM-<g RNA was processed using WT-Ovation Pico RNA Amplification System (NuGEN) paired with the WT-Ovation Exon Module and FL-Ovation cDNA Biotin Module (NuGEN). A detailed protocol in the userM-bM-^@M-^Ys guide kit was used without modification. cDNA were prepared for hybridization on GeneChip Mouse Gene 1.0 ST Arrays (Affymetrix) according to the instructions in GeneChip Hybridization Wash and Stain Kit for ST arrays (Affymetrix). Microarray hybridization, scanning and preliminary MAS 5.0 normalizations were completed at the A*STAR Biopolis Shared Facilities (BSF).

Project description:Purpose: Due to the rarity of Merkel Cell Carcinoma (MCC), prospective clinical trials have not been practical. This study seeks to identify biomarkers to differentiate between patients with a good and poor prognosis. Methods: Patients were stratified into good, moderate or poor prognosis. Merkel cell carcinoma (MCC) patients were stratified into one of three groups based upon status 24 months following treatment. Poor prognosis patients either presented with or progressed to distant metastasis. Patients with favorable prognosis had local disease presentation with no subsequent recurrence or nodal disease at presentation with no progression during follow-up of longer than 24 months. Moderate prognosis had recurrent local disease, development of nodal metastasis, or nodal disease at presentation with no progression during follow-up of fewer than 24 months. Using ArcturusXT Laser Capture Microdissection (Molecular Devices), tumor cells were isolated from the specific areas of interest. The captured tumor tissue was subjected to RNA extraction using the Invitrogen PureLinkM-bM-^DM-" FFPE RNA Isolation Kit. The extracted RNA was analyzed for integrity with the Agilent Bioanalyzer then amplified and hybridized to Affymetrix GeneChip Human Exon 1.0 ST arrays using the NuGEN WT- OvationM-bM-^DM-" FFPE System. Results: A total of 191 genes showed significant differential expression (pM-bM-^IM-$0.05 and 1.5-fold cutoff) between the different between the good and poor prognosis groups. Keratin 20 (KRT20) and Neurofilament protein (NEFM) have been identified in previous studies as proteins of interest in MCC. Our study showed these genes to be significantly upregulated in patients with a poor prognosis. Of interest, phospholipase A2, group X was upregulated in poor responders. Phospholipases liberate arachidonic acid from cellular membranes which can be metabolized to eicosanoids through three major pathways: the cyclooxygenase (COX), the lipoxygenase (LOX) and the cytochrome P450 monooxygenase pathways. This pathway has been implicated in several cancers. Conclusions: The study identified genes with a previous association with MCC as well as some novel genes. These genes provide the basis for further research into possible biomarkers that will enable the differentiation between patients with a good and poor prognosis. Using laser capture microdissection, tumor cells of patients with a good (n=5), moderate (n=3), and poor prognosis (n=7) were isolated from paraffin embedded archival tissue of 15 patients with Merkel cell carcinoma. Affymetrix Human Exon 1.0ST microarrays were utilized to compare gene expression signatures from good and poor prognosis patients.

Project description:Haematopoietic stem cells (HSCs) reside in bone marrow (BM) niches where they are maintained to replenish all blood cell lineages throughout life. Among the constituents of the murine HSC niches, various cell types such as CXCL12-abundant reticular (CAR) cells, Nestin-GFP+ perivascular cells, leptin receptor (LepR)+ cells, endothelial cells, osteoblasts, sympathetic nerves, macrophages and megakaryocytes in the BM have been proposed to contribute to HSC niche activity. When niche cells are removed from their natural habitat, the ability to maintain HSCs ex vivo is markedly diminished. Mesenchymal-derived stromal cells (MSCs) identified by Nestin-GFP express high levels of niche factors in vivo, but their expression is downregulated rapidly upon culture, suggesting that alterations in transcriptional rewiring may contribute to the reduced HSC maintenance potential. We found that the enforced expression of 5 genes (Klf7, Ostf1, Xbp1, Irf3 and Irf7) markedly restored HSC niche function in cultured BM-derived MSCs. These revitalized MSCs (rMSCs) exhibited boosted synthesis of HSC niche factors while retaining their mesenchymal lineage differentiation capacity. By contrast to HSCs co-cultured with control MSCs, HSCs expanded with rMSCs showed significantly higher repopulation capacity. To evaluate to what extent rMSCs are reprogrammed toward freshly isolated MSCs, we compared, by RNA-seq analysis, the transcriptome of freshly sorted CD45(-) Ter119(-) CD31(-) Scf-GFP(-) cells, CD45(-) Ter119(-) CD31(-) Scf-GFP(+) cells, rMSCs and control vector-transduced stroma. HSC niche-associated genes were highly expressed in both native Scf-GFP(+) stromal cells and rMSCs compared to the Scf-GFP cell fraction and control MSCs. With the motif analysis of ATAC-seq data, we found that myocyte enhancer factor 2c (Mef2c) is one of the key factor in the revitalization of MSCs. These results suggest that rMSC may provide a promising platform for curative transplantation therapies.

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Scf-GFP+ cells from the bone marrow and whole bone marrow microarray

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Endothelial and perivascular cells maintain haematopoietic stem cells.

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