SPECIFICITY OF HYDROPEROXY FATTY-ACID INHIBITION OF CELL-GROWTH AND THE LACK OF EFFECT ON TUMOR NECROSIS FACTOR-INDUCED CYTOTOXICITY IN WEHI CLONE-13 CELLS

We have examined whether different omega 6-hydroperoxy fatty acids aff ect tumour cell growth or modulate TNF-induced toxicity in a fatty aci d specific way in WEHI clone 13 fibrosarcoma cells. The omega 6-hydrop eroxides were synthesized from 8 different n-6 and n-3 PUFAs by soybea n lipoxygenase. The omega 6-hydroperoxy fatty acids inhibited cell gro wth in a concentration-dependent way by a mechanism that is related to the hydroperoxy moiety. Intracellular GSH seemed to protect since the GSH synthase inhibitor L-buthionine-S,R-sulfoximine (BSO) increased c ell growth inhibition further. The antioxidants butylated hydroxyaniso le (BHA), butylated hydroxytoluene and alpha-tocopherol did not affect the toxicity. The extent of growth inhibition varied between the hydr operoxides, but the difference was relatively small. The most toxic wa s hydroperoxy-a-linolenic acid which reduced cell survival by 56% afte r 44 h incubation at 35 mu M, while the least toxic, hydroperoxy-gamma -linolenic acid, reduced cell survival by only 10%. The data also show that there is no correlation between toxicity and degree of unsaturat ion of the hydroperoxy fatty acids. None of the 8 different hydroperox y fatty acids potentiated TNF-induced toxicity. This, together with th e differential effects of BHA and BSO on TNF- and hydroperoxy fatty ac id toxicity, indicate that neither the hydroperoxides nor their metabo lites are involved in mediating or modulating the TNF-effect. (C) 1997 Elsevier Science B.V.