Expression of the c-fos oncogene in chemically-induced mouse tumours and in human skin tumours.

Using a polyclonal antibody to fos oncoprotein and an immunofluorescent technique, we investigated expression of the fos oncogene in chemically-induced mouse tumours and human premalignant and malignant skin lesion. In the chemically induced tumours, the nuclei of almost all carcinoma cells stained uniformly with this antibody, while positive cells were observed in the outermost layers in the benign papillomas. In human tumours, a greater degree of nuclear staining was observed in cases of squamous cell carcinoma than in tissues from patients with Bowen's disease. Basal cell carcinoma and malignant melanoma with histological evidence of invasiveness of the tumour cells showed a higher expression of the fos gene product than that seen in histologically circumscribed tumour nests. Thus, a higher expression of the fos oncogene is closely related to the malignant progression of tumour cells, in particular, the extent of invasiveness.