MUTUAL DEPENDENCE OF GROWTH MODIFYING EFFECTS OF 4-HYDROXYNONENAL AND FETAL CALF SERUM IN-VITRO

Recently, the hypothesis has been put forward that 4-hydroxynonenal (HNE), an aldehydic product of lipid peroxidation, contributes to the mechanisms of oxygen toxicity and to the selective pressure exerted by exposure to hyperoxia. Here it has been studied whether HNE itself is involved in mechanisms that convey increased resistence of the cells to the toxicity of HNE. The following four cell lines, different in their basic biological features, were used: nonmalignant Chinese hamster lung fibroblasts V79 (established cell line), human carcinoma HeLa (established cell line), pigmented murine melanoma B16f10 (primary culture), and amelanotic murine melanoma B16BL6 (primary culture). The cells were pretreated in vitro with a toxic dose of HNE (50 mu M), and afterwards the effect of a second exposure to the same dose of HNE on H-3-thymidine incorporation was examined. Cells were cultured in the absence and in the presence of fetal calf serum (FCS), because it had been shown that a growth modifying effect of HNE depends on an unknown serum factor. The results showed that, regardless of the type of cells, preculturing them with 50 mu M HNE in the presence of serum changed the reactivity of the cells to added serum as well as to additional HNE treatment. Thus, HNE precultured cells incorporated less H-3-thymidine in the presence of serum than if cultured under serum-free conditions. On the other hand, HNE precultured cells became less sensitive to further HNE treatment, but only if cultured in the presence of serum. It was concluded that a toxic dose of HNE renders surviving cells more resistent to oxidative stress, possibly by forming a bioactive conjugate with a serum peptide/protein. It is supposed that the same humoral factor might be responsible for the growth modifying effects of high doses of HNE as well as for the growth inhibition in the presence of serum observed for HNE precultured cells.