Original Articles: Translational ResearchUtility of histone H3K27me3 and H4K20me as diagnostic indicators of melanomaDavis, Lauren E.a; Shalin, Sara C.b; Tackett, Alan J.aAuthor Information aDepartment of Biochemistry and Molecular Biology bDepartments of Pathology and Dermatology, University of Arkansas for Medical Sciences, Arkansas, USA Received 10 April 2019 Accepted 6 September 2019 Correspondence to Alan J. Tackett, PhD, Department of Biochemistry and Molecular Biology, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA, Tel: +1 501 686 8152; fax: +1 501 686 8169; e-mail: email@example.com Melanoma Research: April 2020 - Volume 30 - Issue 2 - p 159-165 doi: 10.1097/CMR.0000000000000648 Buy Metrics Abstract Histone posttranslational modifications (PTMs) have been shown to be dysregulated in multiple cancers including melanoma, and as they are abundant and easily detectable, they make ideal biomarkers. The aim of this study was to identify histone PTMs that could be potential biomarkers for melanoma diagnosis. Previously, we utilized mass spectrometry to identify histone PTMs that were dysregulated in matched melanoma cell lines and found two modifications, H3 lysine 27 trimethylation (histone H3K27me3) and H4 lysine 20 monomethylation (histone H4K20me), that were differentially expressed in the more aggressive compared to the less aggressive cell line. In this study, we performed immunohistochemistry on tissue microarrays containing 100 patient tissue spots; 18 benign nevi, 62 primary, and 20 metastatic melanoma tissues. We stained for histone H3K27me3 and histone H4K20me to ascertain whether these histone PTMs could be used to distinguish different stages of melanoma. Loss of histone H4K20me was observed in 66% of malignant patient tissues compared to 14% of benign nevi. A majority (79%) of benign nevi had low histone H3K27me3 staining, while 72% of malignant patient tissues showed either a complete loss or had strong histone H3K27me3 staining. When we analyzed the staining for both marks together, we found that we could identify 71% of the benign nevi and 89% of malignant melanomas. Histone H3K27me3 or histone H4K20me display differential expression patterns that can be used to distinguish benign nevi from melanoma; however, when considered together the diagnostic utility of these PTMs increased significantly. The work presented supports the use of combination immunohistochemistry of histone PTMs to increase accuracy and confidence in the diagnosis of melanoma. Copyright © 2020 Wolters Kluwer Health, Inc. All rights reserved.