N to regulate cellular processes [1?]. Azanucleoside drugs such as 5-aza-2-deoxycytidine (5-Aza) have been used therapeutically with some success to reactivate silenced genes in epigenetic diseases [4?]. In addition, genome-wide hypomethylation is also associated with tumorigenesis [2, 3] and hence may be useful as an early screening strategy for cancer. While hypomethylation is associated with tumorigenesis, regulatory sequences at specific loci, such as that of tumour suppressor genes, are hypermethylated and detection of which are potentially useful in stratifying patient cohorts and* Correspondence: [email protected]; [email protected] 1 Centre for Personalized NanoMedicine, Australian Institute for Bioengineering and Nanotechnology (AIBN), The University of Queensland, St Lucia, Queensland, Australia Full list of author information is available at the end of the articleinforming clinical decisions [1?, 7]. Most approaches, Cibinetide price however, detect DNA methylation via bisulfite conversion [8, 9] of DNA followed by some form of sequencing [10?3]. To avoid the problems PubMed ID:https://www.ncbi.nlm.nih.gov/pubmed/28250575 associated with bisulfite conversion, affinity capture approaches, such as methyl-binding domain (MBD) proteins or antibodies raised against 5mC, have been adapted to Next Generation Sequencing [14] platforms or other optical detection methods for both genome-wide [15, 16] and gene-specific [17] applications. Useful, simpler, more convenient methods to detect both genome-wide and gene-specific methylation are still lacking and would be useful for both routine diagnostics and research. MBD enrichment approaches are useful and convenient because they avoid the limitations of bisulfite conversion while being very highly specific for 5mC on native double-stranded DNA but not hydroxymethylated (5hmC) or unmethylated DNA [18]. Unfortunately, MBD enrichment approaches are limited by their difficulty in quantifying methylation levels and typically quantitative PCR (or sequencing) is used to measure enrichment levels?2015 Wee et al. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly credited. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.Wee et al. Clinical Epigenetics (2015) 7:Page 2 ofas a proxy estimate of differential methylation [19]. Additionally, the stringency of MBD enrichment reduces with limiting DNA inputs and various strategies including high-salt buffers [19] and alternative MBD enzymes [20] have been devised. Nonetheless, one is still able to infer, with very high stringency, the degree/density of methylation based on the buffer conditions required to recover enriched DNA [14, 19]. In short, the methylation outcomes derived from MBD approaches are generally binary, i.e., yes/no calls and therefore, ideal for identifying highly differentially methylated regions (HDMRs). Colorimetric readouts are also popular in molecular diagnostics because they can be evaluated with the naked eye and have the option for (semi)quantification. One popular colorimetric system is the horse radish peroxidase HRP/H2O2 system coupled to a chromogen e.g., 3,3,5,5-tetramethylbenzidine (TMB) substrate to generate a coloured by-product to signal the presence o.
