THE INHIBITORY EFFECT OF CONJUGATED DIENOIC DERIVATIVES (CLA) OF LINOLEIC-ACID ON THE GROWTH OF HUMAN TUMOR-CELL LINES IS IN PART DUE TO INCREASED LIPID-PEROXIDATION

We have examined the effects of linoleic acid, LA (18:2 n-6) and its n aturally occurring conjugated derivatives (CLA) on the growth of three different lung adenocarcinoma cell lines (A-427 SK-LU-I, A549) and on e human glioblastoma cell line (A-172). CLA everted a dose dependent r eduction in proliferation of the lung adenocarcinoma cell lines with A -427 being the most sensitive one, but had virtually no effect on A-17 2. in contrast, LA had no inhibitory effect on either cell line. A sig nificant increase in lipid peroxidation (measured as formation of malo ndialdehyde, MDA) was observed after exposure of the lung adenocarcino ma cell lines to 40 mu M CLA. This level was approximately 2-fold high er than after exposure to 40 mu M LA. The formation of MDA was complet ely abolished by 30 mu M vitamin E, bur the growth rates were only pot entially restored, indicating that cytotoxic lipid peroxidation produc ts are only in part responsible for the growth inhibitory effects of C LA.