Immunodetection of GLUT1, p63 and phospho-histone H1 in invasive head and neck squamous carcinoma: correlation of immunohistochemical staining patterns with keratinization D E Burstein, C Nagi, D S Kohtz, L Lee & B Wang Department of Pathology, Mount Sinai School of Medicine, New York, NY, USA Date of submission 11 August 2005 Accepted for publication 16 August 2005 Burstein D E, Nagi C, Kohtz D S, Lee L & Wang B (2006) Histopathology 48, 717–722 Immunodetection of GLUT1, p63 and phospho-histone H1 in invasive head and neck squamous carcinoma: correlation of immunohistochemical staining patterns with keratinization Aims: To examine invasive head and neck squamous carcinomas for expression of GLUT1, a glucose trans- porter and marker of increased glucose uptake, glyco- lytic metabolism and response to tissue hypoxia; p63, a p53 homologue that is a marker of the undifferentiated proliferative basaloid phenotype; and phospho-histone H1, a marker of activation of the cell cycle-promoting cyclin-dependent kinases 1 and 2. Methods: Routinely processed slides from 34 invasive squamous carcinomas, including 25 with intraepithel- ial components, were immunostained with anti-GLUT1 (Chemicon), anti-p63 (4A4, Santa Cruz), and anti- phospho-histone H1 (monoclonal 12D11). Results: In keratinizing carcinomas, all three markers were most commonly immunodetected peripherally, with loss of expression in central keratinized zones. In contrast, in non-keratinizing carcinomas, p63 and phospho-histone H1 expression was most commonly observed throughout tumour nests and anti-GLUT1 stained in a pattern suggestive of hypoxia-induced expression (‘antistromal’ staining), in which cells at the tumour–stromal interface were GLUT1– and cells in central, perinecrotic zones showed progressive induc- tion of GLUT1. Intraepithelial components also dis- played basal and ‘antibasal’ GLUT1 staining patterns, homologous to the pro- and antistromal patterns in invasive carcinoma; basal patterns in intraepithelial lesions appeared to be more predictive of keratinizing invasive carcinoma and antibasal intraepithelial stain- ing more predictive of non-keratinizing poorly differ- entiated carcinomas. Conclusions: Keratinizing and non-keratinizing squa- mous carcinomas differ in expression patterns of GLUT1, p63 and phospho-histone H1. In the former, all three markers were typically suppressed in con- junction with keratinization; in the latter, GLUT1 expression was more likely to occur in a hypoxia- inducible pattern and expression of p63 and phospho- histone H1 was unsuppressed. GLUT1 expression patterns in intraepithelial lesions may be predictive of the differentiation status of the associated invasive carcinoma. Keywords: GLUT1 histone H1, p63, phosphorylation-specific antibodies, squamous carcinoma, squamous intraepithelial neoplasia Introduction The molecular events that mediate the transition from intraepithelial to invasive head and neck squamous carcinoma are incompletely characterized. In squa- mous intraepithelial neoplasia the balance between division and maturation becomes disordered, resulting in an abnormally expanded basally oriented zone of dividing undifferentiated cells with progressively dim- inished capacity for maturation and, consequently, progressive reduction of a more superficial zone of differentiated, non-dividing cells. The most extreme Address for correspondence: David E Burstein MD, Department of Pathology, Mount Sinai School of Medicine, 1 Gustave L. Levy Place, New York, NY 10029, USA. Ó 2006 Blackwell Publishing Limited. Histopathology 2006, 48, 717–722. DOI: 10.1111/j.1365-2559.2006.02408.x