Expression of the histone H3 gene in benign, semi-malignant and malignant lesions of the head and neck: a reliable proliferation marker.

To search for a reliable proliferation marker in epithelial head and neck lesions, we have analysed the expression of the histone H3 gene by in situ hybridisation and compared this with the immunoreactivity of the widely used monoclonal antibody Ki-67. In many lesions, the Ki-67 staining failed to delineate proliferation. In contrast, the H3 hybridisation signals were in accordance with the histopathology of the biopsies: in hyperplastic epithelia, significant H3 mRNA levels were only seen in areas with inflammation. Dysplastic cells showed distinctly elevated H3 expression. Benign and semi-malignant tumours, i.e. basal cell carcinomas, showed moderate H3 signals at the periphery. In squamous cell carcinomas, H3 expression was always high at the expanding zone of the tumour and was most extensive in undifferentiated carcinomas. Thus, the expression of the histone H3 gene closely reflected the dynamics of neoplastic growth within and around head and neck tumours.