Oxidative metabolism of 4-hydroxy-2,3-nonenal during diethyl-nitrosamine-induced carcinogenesis in rat liver

In some chemically-induced hepatomas and in cultured transformed cells the aldehyde dehydrogenase activity was found increased in the presence of aromatic aldehyde as substrate. We studied this enzyme during diethyl-nitrosamine carcinogenesis in rat liver by using an aliphatic aldehyde, 4-hydroxynonenal, as substrate. 4-Hydroxynonenal is an important product of lipid peroxidation. The NAD- and NADP-dependent aldehyde dehydrogenase of the cytosolic fraction and the NADP-dependent aldehyde dehydrogenase of the microsomes show higher values in nodules and hepatoma than in normal liver. These results suggest that increased aldehyde dehydrogenase, when 4-hydroxynonenal is used, can be considered a marker of the neoplastic process, in the same way as the level of aldehyde dehydrogenase increased in presence of aromatic aldehyde.