Immunocytochemical detection of oncoproteins in animal and human tumor lines with acquired or inherent multidrug resistance.

In this presentation, we analyze the relationship between protein expression of the protooncogenes c-fos, c-erb B1, c-K-ras, and c-myc and acquired or inherent multidrug resistance (MDR) in a panel of animal (CHO, S 180, L 1210) and human (KTCTL 44, KTCTL 18, CX 1, CXF 94) tumor lines by means of immunocytochemistry. Increased expression of c-fos and c-erb B1 proteins is a constant feature of all resistant cell lines except L 1210 cells, which did not reveal any alteration in oncoprotein expression. No apparent relationship between c-K-ras and c-myc proteins and MDR was found. The immunocytochemical results were corroborated by radioimmunoassays (RIAs). The data indicate that c-fos and c-erb B1 might play a role in the development of MDR.