Sox11 prevents tumorigenesis of glioma-initiating cells by inducing neuronal differentiation.
ABSTRACT Recent findings have shown that malignant tumors contain cancer-initiating cells (CIC), which self-renew and are tumorigenic. However, CICs have not been characterized properly due to lack of specific markers. We recently established a mouse glioma cell line, NSCL61, by overexpressing an oncogenic HRas(L61) in p53-deficient neural stem cells. Using limiting dilution assays, we show that only 2 of 24 NSCL61 clones retained their tumorigenicity in vivo, although the others also expressed oncogenic HRas(L61) and could proliferate in culture. A comparison of the gene expression profiles of tumorigenic and nontumorigenic clones showed that the tumorigenic clones had lost Sox11 expression. We show that overexpression of sox11 prevented tumorigenesis of NSCL61s by inducing their neuronal differentiation accompanied with decreased levels of plagl1. We also show that overexpression of plagl1 abolished neuronal commitment of nontumorigenic cells and induced them to become tumorigenic. Moreover, we show that human glioma-initiating cells lost sox11 expression, and overexpression of sox11 prevented their tumorigenesis in vivo. Together with the clinical evidence showing that downregulation of sox11 mRNA correlates with a significant decrease in survival, these findings suggest that Sox11 prevents gliomagenesis by blocking the expression of oncogenic plagl1.
Article: SOX11 expression correlates to promoter methylation and regulates tumor growth in hematopoietic malignancies.[show abstract] [hide abstract]
ABSTRACT: The transcription factor SOX11 plays an important role in embryonic development of the central nervous system (CNS) and is expressed in the adult immature neuron but is normally not expressed in any other adult tissue. It has recently been reported to be implicated in various malignant neoplasms, including several lymphoproliferative diseases, by its specific expression and in some cases correlation to prognosis. SOX11 has been shown to prevent gliomagenesis in vivo but the causes and consequences of aberrant expression of SOX11 outside the CNS remain unexplained. We now show the first function of SOX11 in lymphoproliferative diseases, by demonstrating in vitro its direct involvement in growth regulation, as assessed by siRNA-mediated silencing and ectopic overexpression in hematopoietic malignancies. Gene Chip analysis identified cell cycle regulatory pathways, including Rb-E2F, to be associated with SOX11-induced growth reduction. Furthermore, promoter analysis revealed that SOX11 is silenced through DNA methylation in B cell lymphomas, suggesting that its regulation is epigenetically controlled. The data show that SOX11 is not a bystander but an active and central regulator of cellular growth, as both siRNA-mediated knock-down and ectopic overexpression of SOX11 resulted in altered proliferation. Thus, these data demonstrate a tumor suppressor function for SOX11 in hematopoietic malignancies and revealed a potential epigenetic regulation of this developmentally involved gene.Molecular Cancer 01/2010; 9:187. · 3.99 Impact Factor
Article: Gene expression profiling and chromatin immunoprecipitation identify DBN1, SETMAR and HIG2 as direct targets of SOX11 in mantle cell lymphoma.[show abstract] [hide abstract]
ABSTRACT: The SRY (sex determining region Y)-box 11 (SOX11) gene, located on chromosome 2p25, encodes for a transcription factor that is involved in tissue remodeling during embryogenesis and is crucial for neurogenesis. The role for SOX11 in hematopoiesis has not yet been defined. Two genes under direct control of SOX11 are the class- III β-tubulin gene (TUBB3) in neural cells and the transcription factor TEA domain family member 2 (TEAD2) in neural and mesenchymal progenitor cells. Normal, mature lymphocytes lack SOX11 but express SOX4, another member of the same group of SOX transcription factors. We and others recently identified SOX11 as aberrantly expressed in mantle cell lymphoma (MCL). Since SOX11 is variably expressed in MCL it may not be essential for tumorigenesis, but may carry prognostic information. Currently, no specific functional effects have been linked to SOX11 expression in MCL and it is not known which genes are under influence of SOX11 in lymphoma. In this study we found variable expression of SOX11, SOX4 and SOX12 mRNA in mantle cell lymphoma cell lines. Downregulation of SOX11 expression by siRNA verified that SOX11 controlled the expression of the gene TUBB3 in the MCL cell line Granta 519. Furthermore we identified, by global gene expression analysis, 26 new target genes influenced by siRNA SOX11 downmodulation. Among these genes, DBN1, SETMAR and HIG2 were found to be significantly correlated to SOX11 expression in two cohorts of primary mantle cell lymphomas. Chromatin immunoprecipitation (ChIP) analysis showed that these genes are direct targets of the SOX11 protein. In spite of almost complete downregulation of the SOX11 protein no significant effects on Granta 519 cell proliferation or survival in short term in vitro experiments was found. In summary we have identified a number of genes influenced by SOX11 expression in MCL cell lines and primary MCL. Among these genes, DBN1, SETMAR and HIG2 are direct transcriptional targets of the SOX11 protein.PLoS ONE 01/2010; 5(11):e14085. · 4.09 Impact Factor