Immunohistochemical Mdm2 expression in minor salivary gland tumours and its relationship to p53 gene status

Mdm2 protein is a cellular regulator of p53 protein activity. Minor salivary gland tumours were investigated for immunohistochemical expression of Mdm2 protein and for p53 gene status. Formalin-fixed sections were submitted to monoclonal antibody anti-Mdm2 through use of the streptavidin–biotin method. Nuclear immunoreactivity was scored 1 (0–25% nuclei positive), 2 (26–50%), 3 (51–75%) and 4 (>75%). The scores found were: PLGA=1–4; ACC=3 and 4; ACA=2 and 4; PA=3. Genomic DNA of p53 gene exons 5–8 was examined by polymerase chain reaction and no alterations were detected. The strong immunohistochemical Mdm2 expression may represent an alternative mechanism to the development of salivary gland tumours.