Merkel cells of human oral mucosa express the pluripotent stem cell transcription factor Sox2
Lucía García-Caballero1, Javier Caneiro1,2, Marina Gándara1,2, Noel González-Ortega3, Alfonso Cepeda-Emiliani1, Francisco Gude4, Manuel Collado5, Andrés Beiras1 and Rosalía Gallego1
1Department of Morphological Sciences, School of Medicine and Dentistry, University of Santiago de Compostela, 2Department of Pathology, University Clinical Hospital, Santiago de Compostela, 3Department of Pathology, Mateu Orfila General Hospital, Mahon, Mallorca, 4Epidemiology Unit, University Clinical Hospital and 5Laboratory of Stem Cells in Cancer and Aging, Health Research Institute of Santiago (IDIS), Santiago de Compostela, Spain
Offprint requests to: Lucía García-Caballero, Department of Morphological Sciences, School of Medicine and Dentistry, University of Santiago de Compostela, San Francisco, s/n 15782, Santiago de Compostela, Spain. e-mail: lucia.garcia.caballero@usc.es
Summary. Merkel cells are neuroendocrine cells associated to a neural sensitive ending and localized primarily in the epidermis, although they are also found in oral mucosa. Sox2 or SRY-box2 is a key transcription factor important in the maintenance of embryonic neural crest stem cell pluripotency. Sox2 has been described in Merkel cells of skin and in Merkel cell carcinomas, but not specifically in oral Merkel cells. The aims of the present study were to analyze the density of Merkel cells in human oral mucosa and to study the expression of Sox2 in these cells. For these purposes, immuno-histochemical analyses for Sox2 and CK20 (the best marker for Merkel cells) were automatically performed on sections of normal human oral mucosa. Double immunofluorescence for Sox2 and CK20 was also performed. To analyze the density of Merkel cells, CK20 positive cells were counted in each sample and the length of the epithelial apical edge was measured (cells/mm). Merkel cells, demonstrated by CK20 immunoreactivity, were found in 95% of oral mucosa specimens studied (n=21). Mean density of Merkel cells in oral mucosa was 1.71±2.34 cells/mm. Sox2 immunoreactivity was found in the nuclei of scattered cells located at the basal layer. Serial sections immunostained for Sox2 and CK20 showed that Sox2-positive cells of oral mucosa coexpressed CK20, confirming that they were Merkel cells. Immuno-fluorescence for Sox2 and CK20 showed colocalization of both markers, demonstrating that virtually all oral Merkel cells expressed Sox2. This transcription factor could play a role in Merkel cell maturation and maintenance. Histol Histopathol 35, 1007-1012 (2020)
Key words: Merkel cells, Sox2, Oral mucosa, Immunohistochemistry, Double immunofluorescence
DOI: 10.14670/HH-18-231