Label-free electrochemical detection of human methyltransferase from tumors
The role of abnormal DNA methyltransferase activity in the development and progression of cancer is an essential and rapidly growing area of research, both for improved diagnosis and treatment. However, current technologies for the assessment of methyltransferase activity, particularly from crude tumor samples, limit this work because they rely on radioactivity or fluorescence and require bulky instrumentation. Here, we report an electrochemical platform that overcomes these limitations for the label-free detection of human DNA(cytosine-5)-methyltransferase1 (DNMT1) methyltransferase activity, enabling measurements from crude cultured colorectal cancer cell lysates (HCT116) and biopsied tumor tissues. Our multiplexed detection system involving patterning and detection from a secondary electrode array combines low-density DNA monolayer patterning and electrocatalytically amplified DNA charge transport chemistry to measure selectively and sensitively DNMT1 activity within these complex and congested cellular samples. Based on differences in DNMT1 activity measured with this assay, we distinguish colorectal tumor tissue from healthy adjacent tissue, illustrating the effectiveness of this two-electrode platform for clinical applications.
© 2014 National Academy of Sciences. Contributed by Jacqueline K. Barton, September 8, 2014 (sent for review August 21, 2014; reviewed by Royce W. Murray). Published ahead of print October 6, 2014. We thank Dr. Bert Vogelstein (The Johns Hopkins University) for the HCT116 parent and DNMT1^(−/−) cell lines, and the National Institutes of Health (GM61077) for their support of this research. Author contributions: A.L.F., N.B.M., M.G.H., and J.K.B. designed research; A.L.F. performed research; A.L.F., N.B.M., and M.G.H. analyzed data; and A.L.F., N.B.M., and J.K.B. wrote the paper. Reviewer: R.W.M., The University of North Carolina at Chapel Hill. The authors declare no conflict of interest. This article contains supporting information online at www.pnas.org/lookup/suppl/doi:10.1073/pnas.1417351111/-/DCSupplemental.
Published - 14985.full.pdf
Supplemental Material - pnas.201417351SI.pdf