No tumor-specific expression levels of protein kinase C isoenzymes and of c-fos in human breast cancer cell cultures.
Epithelial cells derived from 46 human breast tissue samples of patients suffering from breast cancer have been cultivated. Twenty-five of these cell cultures stemmed from normal and 21 from tumor tissues. Moderate to large variations of protein levels of three protein kinase C (PKC) isoenzymes (alpha, delta and epsilon) were found among the various cell cultures. The cell cultures also exhibited very heterogeneous basal as well as inducible levels of c-fos mRNA. However, none of these variations could be correlated with the character of the original tissue nor with any clinical parameter of the respective patient. Our results suggest that altered levels of PKC isoenzymes or of the protooncogene c-fos per se cannot serve as an indication for a transformed behavior of the epithelial cell fraction of human breast tissue.