The nuclear matrix shell proteome of human epidermis Raymond L. Warters a,c , Pamela B. Cassidy b,c,d , Jeremy A. Sunseri b,c , Krishna Parsawar e , Sergey B. Zhuplatov a , Gwen F. Kramer a , Sancy A. Leachman b,c, * a Department of Radiation Oncology, University of Utah Health Sciences Center, Salt Lake City, UT 84132, United States b Department of Dermatology, University of Utah Health Sciences Center, Salt Lake City, UT 84132, United States c Huntsman Cancer Institute, University of Utah Health Sciences Center, Salt Lake City, UT 84132, United States d Department of Medicinal Chemistry, University of Utah Health Sciences Center, Salt Lake City, UT 84132, United States e Mass Spectrometry and Proteomics Core Facility, University of Utah Health Sciences Center, Salt Lake City, UT 84132, United States 1. Introduction Cancer of the skin is the most common form of human cancer and accounts for about half of all new cancer cases in the United States. Major skin cancer subtypes include basal cell carcinoma, squamous cell carcinoma and malignant melanoma. Although melanoma represents only about 5% of all skin cancers, it is the most deadly type if left untreated, accounting for about 75% of all skin cancer deaths. Melanoma is now the sixth and seventh most common cancer developed in American men and women, respectively, and will represent about 1.7% of all cancer deaths, in the USA in 2008 [1]. Melanomas develop via malignant transformation of melano- cytes that either reside adjacent to the basal lamina in the basal layer of the epidermis (i.e. the normal melanocytes responsible for pigment production in the skin), or via transformation of melanocytes within melanocytic nevi (i.e. ‘‘moles’’ that are a benign tumor of melanocytic cells that can serve as melanoma precursors) [2,3]. Aberrant melanocyte proliferation gives rise to nevi. Banal melanocytic nevi are extremely common and the rate of transformation to malignancy is relatively low [4]. However, patients with an increased number and/or increased size of nevi, or with clinically atypical nevi, are at increased risk for development of melanoma. Regardless of the initial source of melanocyte transformation, most melanomas initially proliferate within the epidermis (in situ), progressing to a radial growth phase along the Journal of Dermatological Science 58 (2010) 113–122 ARTICLE INFO Article history: Received 28 August 2009 Received in revised form 27 February 2010 Accepted 1 March 2010 Keywords: Human epidermis Nuclear matrix Melanoma Intermediate filaments ABSTRACT Background: Proteomic approaches have identified cancer specific biomarker proteins in the nuclear matrix fraction of cancer cells. We wanted to determine whether a similar approach could be used to investigate melanoma biomarkers. Objective: Since it was not clear that a nuclear matrix fraction could be isolated from the intact human epidermis, we first wanted to determine whether a nuclear matrix fraction could be isolated from the intact epidermis of human skin. If this was possible, we secondarily wanted to compare the proteome of cultured melanoma and carcinoma cells to that of the intact epidermis. Methods: We applied two-dimensional electrophoresis (2DGE) and LC/MS/MS to identify proteins isolated in the nuclear matrix shell protein fraction isolated from the human epidermis and from cultured primary skin and cancer cells. Results: A subcellular fractionation of intact epidermis succeeded in yielding a nuclear matrix shell which made up approximately 40% of total tissue protein. Only 5–10% of total cell protein was fractionated in the nuclear matrix shell of cultured skin cells. The nuclear matrix shell of the intact epidermis was distinguishable from cultured keratinocytes or HaCaT cells by expression of keratin 1. The nuclear matrix of the epidermis was distinguishable from melanocytes and melanoma cells by expression of vimentin in melanocyte-derived cells and by expression of desmoplakin in the intact epidermis. Conclusion: The nuclear matrix-intermediate filament system can be isolated from the intact human epidermis. A careful examination of the protein composition of this subcellular fraction from the epidermis and skin cancers may identify useful cancer specific biomarkers. Published by Elsevier Ireland Ltd on behalf of Japanese Society for Investigative Dermatology. Abbreviations: 2DGE, two-dimensional gel electrophoresis; FT-ICR, Fourier trans- form-ion cyclotron resonance mass spectrometer; HBSS, Hanks balanced salt solution; IEF, isoelectric focusing; IPG, immobilized pH gradient; LC, liquid chromatography; LTQ-FT, linear ion trap–Fourier transform; MS, mass spectro- metry. * Corresponding author at: c/o Michelle Judd, Administrative Assistant, Hunts- man Cancer Institute, 2000 Circle of Hope, Rm. 5241, Salt Lake City, UT 84112, United States. Tel.: +1 801 585 9427; fax: +1 801 585 7477. E-mail address: sancy.leachman@hci.utah.edu (S.A. Leachman). Contents lists available at ScienceDirect Journal of Dermatological Science journal homepage: www.elsevier.com/jds 0923-1811/$36.00 . Published by Elsevier Ireland Ltd on behalf of Japanese Society for Investigative Dermatology. doi:10.1016/j.jdermsci.2010.03.001