Regulation of the stem cell marker CD133 is independent of promoter hypermethylation in human epithelial differentiation and cancer

Molecular Cancer

Research

Matthew S Simms¹  Marie-Christine Labarthe²  Anne T Collins³  Fiona M Frame³  Paul A Berry³  Richard J Packer³  Emma E Oldridge³  Norman J Maitland³  Davide Pellacani³  Michael J Stower⁴ 

[1] Castle Hill Hospital, Castle Rd, Cottingham, HU16 5JQ, East Yorkshire, UK;Pro-Cure Therapeutics Ltd, The Biocentre, Innovation Way, York Science Park, Heslington, York, UK;YCR Cancer Research Unit, Department of Biology, University of York, Wentworth Way, YO10 5DD, York, UK;York District Hospital, Wigginton Road, City Centre, YO31 8HE, York, UK;

关键词: CD133;    prostate cancer;    cancer stem cells;    epigenetic regulation of gene expression;    DNA methylation;   

DOI  :  10.1186/1476-4598-10-94

 received in 2011-03-14, accepted in 2011-07-29,  发布年份 2011

来源: Springer

【 摘 要 】

BackgroundEpigenetic control is essential for maintenance of tissue hierarchy and correct differentiation. In cancer, this hierarchical structure is altered and epigenetic control deregulated, but the relationship between these two phenomena is still unclear. CD133 is a marker for adult stem cells in various tissues and tumour types. Stem cell specificity is maintained by tight regulation of CD133 expression at both transcriptional and post-translational levels. In this study we investigated the role of epigenetic regulation of CD133 in epithelial differentiation and cancer.MethodsDNA methylation analysis of the CD133 promoter was done by pyrosequencing and methylation specific PCR; qRT-PCR was used to measure CD133 expression and chromatin structure was determined by ChIP. Cells were treated with DNA demethylating agents and HDAC inhibitors. All the experiments were carried out in both cell lines and primary samples.ResultsWe found that CD133 expression is repressed by DNA methylation in the majority of prostate epithelial cell lines examined, where the promoter is heavily CpG hypermethylated, whereas in primary prostate cancer and benign prostatic hyperplasia, low levels of DNA methylation, accompanied by low levels of mRNA, were found. Moreover, differential methylation of CD133 was absent from both benign or malignant CD133+/α2β1integrinhi prostate (stem) cells, when compared to CD133-/α2β1integrinhi (transit amplifying) cells or CD133-/α2β1integrinlow (basal committed) cells, selected from primary epithelial cultures. Condensed chromatin was associated with CD133 downregulation in all of the cell lines, and treatment with HDAC inhibitors resulted in CD133 re-expression in both cell lines and primary samples.ConclusionsCD133 is tightly regulated by DNA methylation only in cell lines, where promoter methylation and gene expression inversely correlate. This highlights the crucial choice of cell model systems when studying epigenetic control in cancer biology and stem cell biology. Significantly, in both benign and malignant prostate primary tissues, regulation of CD133 is independent of DNA methylation, but is under the dynamic control of chromatin condensation. This indicates that CD133 expression is not altered in prostate cancer and it is consistent with an important role for CD133 in the maintenance of the hierarchical cell differentiation patterns in cancer.

【 授权许可】

CC BY   
© Pellacani et al; licensee BioMed Central Ltd. 2011