Investigating Methyl-Cpg Dna Recognition In Cancer

DNA methylation is an essential epigenetic modification in eukaryotes required for genomic stability, control of gene expression and regulation of chromatin structure. Consequently, abhorrent alterations in methyl-CpG modifications across the genome, leading to inappropriate transcription, are associated with many diseases including cancer. Thus, an interest in discerning the regulatory mechanisms linking DNA methylation with gene expression in the disease state has emerged. The ZBTB methyl-CpG binding proteins (MBPs) are specialized transcription factors that mediate transcription by specifically targeting both methylated and sequence-specific DNA sites through a conserved set of Cys2His2 zinc fingers. While ZBTB MBP expression has become increasingly associated with higher grade tumors, we have only begun to understand the underlying complexities by which this family mediates gene expression. Here we combine interdisciplinary in cell genomic with in vitro biophysical approaches to begin to delineate the mechanisms by which this family of MBPs recognize DNA and regulate transcription in cancer. Specifically, for the founding member of this MBP family we utilized multiple genome-wide methodologies to identify its genomic targets, the methylation status at these sites and the transcriptional effect of this protein in cancer cell lines. We observed that protein expression levels, gene occupations and transcriptional responses were variable between cancer phenotypes. Additionally, ZBTB depletion results in variable phenotypic alterations between cell types indicating that protein presence may provide a means for defining these pathological states. Further, we have designed multiple protein constructs around the zinc finger domains of the ZBTB MBPs. Biophysical characterization of the binding interactions of these protein regions with various epigenetically modified DNAs has provided preliminary understanding for the differential mode of DNA recognition exhibited by the ZBTB MBP family members. Together, these findings provide initial insights into the molecular basis by which these proteins preferentially recognize, interpret and translate epigenetic signals into transcriptional responses in cancer cells. Citation Format: Tommy W. Terooatea, Megan J. Wallace, Marta W. Szulik, Alan C. Chugg, Sven Miller, Bethany A. Buck-Koehntop. Investigating methyl-CpG DNA recognition in cancer. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 2957. doi:10.1158/1538-7445.AM2015-2957