Department of Bioactive Molecules , National Institute of Health , Tokyo , Japan .
Oncogene 8 : 1731-5 ( 1993)
Abstract
We developed a new method for evaluating inhibitors of oncogenic signal transduction pathways based on different growth abilities between normal and transformed cells in a defined serum-free medium .
The growth rates of src , abl or ras oncogene-transformed cells , activated raf proto-oncogene transformed cells , and normal NIH-3T3 cells were 60-90% , -30% and 10% in a serum-free medium , respectively , compared to the growth rates in a serum-containing medium .
An addition of a growth factor ( PDGF , FGF or TGF-beta ) stimulated the growth of normal NIH3T3 cells by 40-80% in a serum-free medium .
Herbimycin A , a specific cytoplasmic protein tyrosine kinase inhibitor , selectively inhibited the growth of src or abl transformed cells in the serum-free medium resulting in about 10-fold or fivefold lower IC50 than those in the serum-containing medium .
The antibiotic did not show such an effect on ras transformed cells , and the treatment of src transformed cells with other protein kinase inhibitors or cytotoxic drugs showed little IC50 shifts between the two media .
Thus , this method of comparing growth inhibition in the serum-free and the serum-containing media may be useful in evaluating specific inhibitors of signaling pathways mediated by growth factors and certain oncogene products .