The expression of placental-type glutathione S-transferase (GST-pi) in human cutaneous squamous cell carcinoma and normal human skin.

The expression of human placental-type glutathione S-transferase (GST-pi) was investigated in human cutaneous squamous cell carcinoma (SCC) and normal skin using Northern blot and immunohistochemical analysis. In Northern blot examination, the expression of GST-pi transcript was recognized in all instances, and SCC showed a significantly higher expression of GST-pi than normal skin. In immunohistochemical examination, GST-pi was stained well in the cytoplasm of all cells of the stratum granulosum, many cells of the stratum spinosum and a few cells of the stratum basale in normal skin. Some cells of the stratum spinosum and almost all cells of the stratum basale showed only a weakly positive or almost negative reaction for GST-pi. No nuclear staining of GST-pi was obvious in normal epidermal cells. In SCC, many cells showed strong positivity for GST-pi in the cytoplasm, and some were obviously accompanied by nuclear staining of GST-pi. These findings suggest that GST-pi exists mainly in many cells in the upper layers of the normal epidermis and that GST-pi is involved in the process of carcinogenesis.