https://orcid.org/0000-0001-5429-0152
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ABSTRACT
Background: Liquid biopsies offer significant potential for informing on cancer progression and therapeutic resistance via minimally invasive serial monitoring of genetic alterations. Although the cancer epigenome is a central driving force in most neoplasia, the accuracy of monitoring the tumor methylome using liquid biopsies remains relatively unknown. Objectives: to investigate how well two types of liquid biopsy (urine and blood) capture the prostate cancer methylome, and may thus serve as a non-invasive surrogate for studying the tumor epigenome. Methods: A cohort of four metastatic treatment naïve prostate cancer (PCa) patients was selected. Matched biopsy cores (tumor and histologically matched-normal), post-DRE, pre-biopsy urine, and peripheral blood plasma were available for each subject. DNA methylation was profiled utilizing the Infinium® MethylationEPIC BeadChip (Illumina) and analysed using the RnBeads software. Significantly (FDR adjusted P < 0.05) differentially methylated probes (DMPs) between tumor and MN were identified and examined in the liquids (done at a grouped and individual subject level). Results: DNA methylation analysis of urine and blood in men with metastatic PCa showed highly correlated patterns between the different liquid types (ρ = 0.93, P < 0.0001), with large contributions from non-tumor sources. DNA methylation profiles of liquids were more similar between subjects, than intra-individual liquid-tumor correlations. Overall, both urine and plasma are viable surrogates for tumor tissue biopsies, capturing up to 39.40% and 64.14% of tumor-specific methylation alterations, respectively. Conclusion: We conclude that both urine and blood plasma are easily accessible and sensitive biofluids for the study of PCa epigenomic alterations.
Acknolwedgements
We gratefully acknowledge the support of iPROSPECT investigators (R.W.G Watson, R. McDermott and S. Glynn) and the HRB-funded Dublin Centre for Clinical Research Network, affiliated research nurses and technical staff, in particular John McCourt.
Disclosure statement
No potential conflict of interest was reported by the authors.
Author contributions
Conception and design: A.S. Perry, Development of methodology: R. Silva, B. Moran, C. Fahey, Acquisition of data (acquired and processed samples): R. Silva, C. Fahey, Histological evaluation of prostate biopsy cores: T. Vlajnic, S.P. Finn, Analysis and interpretation of data (e.g., statistical analysis, biostatistics, computational analysis): R. Silva, B. Moran, N.M. Russel, A.S. Perry, Writing and review of the manuscript: R. Silva, B. Moran, N.M. Russel, R. Manecksha, W. M. Gallagher, D. Brennan, A.S. Perry. Study supervision: W. M. Gallagher and A.S. Perry.
Supplementary material
Supplemental data for this article can be accessed here.