Expression of class Pi glutathione transferase in human malignant melanoma cells.

The occurrence of glutathione transferase in human malignant melanoma cell lines and solid tumor material has been analyzed and compared with the enzyme composition in fibroblasts and naevus samples. All cells and tissues investigated contained essentially only the acidic class Pi glutathione transferase as demonstrated by SDS-PAGE and immunoblotting. The enzyme was purified from tumor material and characterized. Its intracellular concentration was significantly higher in all the melanoma cell preparations analyzed than in the non-malignant cells, supporting the view that the class Pi glutathione transferase may contribute to the drug resistance that is characteristic of malignant melanoma.