Project description:Over-expression of the polycomb group gene BMI-1 is implicated in the pathogenesis of many human cancers. In this study, we investigate the role of BMI-1 as a functional oncogene in the Ewing’s Sarcoma Family of Tumors (ESFT), a highly aggressive group of bone and soft tissue tumors. Our data show that BMI-1 is highly expressed by the majority of primary ESFT and ESFT cell lines. However, in contrast to previous reports in other human cancer cell types, knockdown of BMI-1 in ESFT cell lines has no effect on cell survival. Instead, gain and loss of function studies in vitro and in vivo demonstrate that BMI-1 promotes the anchorage independent growth and tumorigenicity of ESFT. Importantly, we also find that modulation of BMI-1 alters the tumorigenicity of both p16-wild type and p16-null cell lines and that BMI-1-mediated effects on growth promotion are independent of CDKN2a repression. Gene expression profiling of ESFT cells following BMI-1 modulation reveals novel downstream effectors of BMI-1 function including key developmental, cell:cell and cell:matrix adhesion pathways. These data support a central role for BMI-1 in the pathogenesis of ESFT and reveal that p16-independent functions of BMI-1 are largely responsible for its oncogenic function in this tumor family. Keywords: Modification of BMI-1 expression in ESFT cell lines
Project description:Multiple myeloma is associated with an immunosuppressive bone marrow microenvironment instigated and maintained by crosstalk between multiple myeloma cells and the surrounding cells. This crosstalk is facilitated or hindered by epigenetic modifiers altering the gene expression of receptors. The Polycomb-like protein PHF19/PCL3, which mediates polycomb repressive complex 2 (PRC2) recruitment to chromatin, is a high-risk gene whose expression level correlates with poor prognosis in MM patients. Here, we used ATAC seq to define the chromatin accessibility and transcriptional landscape controlling this process by PHF19.
Project description:Bmi-1 and Mel-18 are close structural homologues that belong to the polycomb group (PcG) of transcriptional regulators of homeotic gene expression in development. They are believed to stably maintain repression of gene expression by altering the state of chromatin at specific promoters. A number of clinical and experimental observations have also implicated Bmi-1 in tumorigenesis and stem cell maintenance. Bmi-1 overexpression or amplification has been observed in a number of human malignancies, particularly in B-cell lymphomas, medulloblastomas and breast cancer. We report here that shRNA-mediated knock-down of either Bmi-1 or Mel-18 in human medulloblastoma DAOY cells results in the inhibition of proliferation, loss of clonogenic survival and anchorage-independent growth, and suppression of xenograft tumor formation in nude mice. Furthermore, overexpression of both Bmi-1 and Mel-18 significantly increased clonogenic survival of Rat1 fibroblasts. In contrast, stable downregulation of Bmi-1 or Mel-18 alone did not affect the growth of SK-OV-3 or U2OS cancer cell lines or normal human WI38 fibroblasts. Gene expression analysis of shRNA-expressing DAOY cells has demonstrated a significant overlap in the Bmi-1- and Mel-18-regulated genes and revealed novel gene targets under their control. Taken together, these results suggest that Bmi-1 and Mel-18 might have overlapping functions in human tumorigenesis. Keywords: shRNA knock-down
Project description:<h4><strong>BACKGROUND:</strong> Multiple myeloma is characterized by clonal proliferation of malignant plasma cells in the bone marrow that produce monoclonal immunoglobulins. N-glycosylation changes of these monoclonal immunoglobulins have been reported in multiple myeloma, but previous studies only detected limited serum N-glycan features.</h4><h4><strong>METHODS:</strong> Here, a more detailed study of the human serum N-glycome of 91 multiple myeloma patients and 51 controls was performed. We additionally analyzed sequential samples from patients (n = 7) which were obtained at different time points during disease development as well as 16 paired blood serum and bone marrow plasma samples. N-glycans were enzymatically released and measured by mass spectrometry after linkage specific derivatization of sialic acids.</h4><h4><strong>RESULTS:</strong> A decrease in both α2,3- and α2,6-sialylation, galactosylation and an increase in fucosylation within complex-type N-glycans were found in multiple myeloma patients compared to controls, as well as a decrease in difucosylation of diantennary glycans. The observed glycosylation changes were present in all ISS stages, including the 'low-risk' ISS I. In individual patients, difucosylation of diantennary glycans decreased with development of the disease. Protein N-glycosylation features from blood and bone marrow showed strong correlation. Moreover, associations of monoclonal immunoglobulin (M-protein) and albumin levels with glycan traits were discovered in multiple myeloma patients.</h4><h4><strong>CONCLUSIONS & GENERAL SIGNIFICANCE: </strong>In conclusion, serum protein N-glycosylation analysis could successfully distinguish multiple myeloma from healthy controls. Further studies are needed to assess the potential roles of glycan trait changes and the associations of glycans with clinical parameters in multiple myeloma early detection and prognosis.</h4>
Project description:Polycomb-group proteins form multimeric protein complexes involved in transcriptional silencing. The Polycomb Repressive complex 2 (PRC2) contains the Suppressor of Zeste-12 protein (Suz12) and the histone methyltransferase Enhancer of Zeste protein-2 (Ezh2). This complex, catalyzing the di- and tri-methylation of histone H3 lysine 27, is essential for embryonic development and stem cell renewal. However, the role of Polycomb-group protein complexes in the control of the intestinal epithelial cell (IEC) phenotype is not known. We investigated the impact of Suz 12 depletion on gene expression in IEC-6 cells.