Localization of adenosine triphosphatase activity in preneoplastic and cancerous cells of the mouse skin induced by methylcholanthrene.

Abstract

The localization of membrane-bound adenosine triphosphatase activity has been studied by both light and electron microscopy in the normal epidermis and in methylcholanthreneinduced preneoplastic alterations, i.e., hyperplasia, papilloma and also in similarly induced cancers of the skin of mice. In normal epidermis, the adenosine triphosphatase activity was seen to be located in contact with all of the cell membranes facing the intercellular spaces. In preneoplastic alterations, the enzyme activity was found along the cell membranes of the basal and suprabasal cells of the epithelial pegs and numerous dense deposits of lead phosphate could be seen on the surfaces of the cytoplasmic processes and in the enlarged intercellular spaces. The intensity of the reaction in preneoplastic conditions was greater than in the normal epidermis. No adenosine triphosphatase activity was observed in the cell membranes facing the basement membrane or in the desmosomes. In carcinoma a less intensive adenosine triphosphatase reaction was present and could be recognized on the surface of only few tumor cells.