non-parenchymal cell co-cultures

1To whom correspondence should be addressed Peroxisome proliferators (PP) are known hepatocarcino-gens in rats and mice. We have investigated the ability of Wyeth-14 643 (Wy), a PP and potent rodent carcinogen, to induce replicative DNA synthesis and to modulate the levels of peroxisome proliferator activated receptor-alpha (PPARα) transcriptionally-dependent genes in primary rat hepatocyte (HPC) cultures and hepatocyte/non-parenchymal cell (HPC/NPC) co-cultures maintained on Matrigel. Four days after plating, cells were treated with Wy and replicative DNA synthesis was quantitated using [3H]thymidine incorporation and specific mRNA transcript levels were determined by reverse-transcriptase polym-erase chain reaction (RT-PCR). An increase in HPC rep-licative DNA synthesis was detected at 48 h in both Wy-treated HPC and HPC/NPC co-cultures relative to controls. This increase was approximately 3- and 6-fold in HPC and HPC/NPC cultures respectively, and was Wy concentration-dependent. The levels of PPARα-transcriptionally depend-ent genes [cytochrome P4504A1, acyl-CoA oxidase (AOx-ase), and liver-fatty acid binding protein (L-FABP)] transcripts were determined as indicators of PPARα activa-tion. These transcripts increased dose-dependently at 48 h in HPC/NPC cultures up to 10 µM Wy. Similarly, RT-PCR product levels were also increased in HPC cultures wit