Analyses of the tumour suppressor ING1 expression and gene mutation in human basal cell carcinoma

The incidence of basal cell carcinoma is the highest among all human malignancies. Epidemiological evidence indicates that ultraviolet radiation is the primary environmental cause for the pathogenesis of basal cell carcinoma. However, the genetic changes caused by ultraviolet radiation that lead to basal cell carcinoma formation remain unclear. We and others have demonstrated that the ING1 (inhibitor of growth 1) tumour suppressor plays an important role in cellular stress response to ultraviolet irradiation, such as DNA repair and apoptosis. This study was designed to investigate whether ING1 is overexpressed and/or mutated in human basal cell carcinoma. Immunohistochemistry, single-strand conformation polymorphism, and DNA sequencing were used to determine the expression and mutational status of the ING1 gene in 54 basal cell carcinoma biopsies. Immunohistochemical staining demonstrated that ING1 is overexpressed in 25% (6/24) human basal cell carcinomas. Single-strand conformation polymorphism and DNA sequencing revealed that only 1 in 54 (1.8%) basal cell carcinoma primaries contained a missense mutation in the ING1 gene. The mutation is located in exon 2 and could thus potentially interfere with the structure of every ING1 isoforms and the functions of the PHD zinc finger motif. Our data indicate that overexpression and mutation of the ING1 gene are infrequent in human basal cell carcinoma.