tretinoin and perfluorooctanoic-acid

Effects of perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS) on the neuronal lineage marker expression, cell-cell interaction, caspase-3 mRNA transcription and reactive oxygen species production by N2a neuronal cells were assesses in 3-dimensional (3D) spheroid cultures, and the cytotoxicity were thoroughly compared with those of a conventional 2D monolayer-based toxicity assay. Increasing concentrations of PFOA or PFOS resulted in an increase in cell death. The half maximal inhibitory concentrations measured with spheroids were approximately one and a half times greater than the respective values for monolayer cells. Necrosis was prevalent in spheroids regardless of the dose, whereas the major injury mechanism in monolayers was dependent on compound concentration. Both PFOA and PFOS inhibited neuronal, astrocyte and oligodendrocyte marker gene expression by monolayers and spheroids grown under undifferentiated and all-trans-retinoic acid-induced differentiating conditions. In the presence of PFOA or PFOS, expression levels of E-cadherin and connexin-43 mRNAs were significantly downregulated, and spheroids were dissociated into single cell populations, indicating that the compounds affect the synthesis of E-cadherin and connexin-43 at the transcriptional level. Results from 3D cultures may provide an insight into potential inhibitory mode of action on gap junctional intercellular communication.

Topics: Alkanesulfonic Acids; Animals; Cadherins; Caprylates; Caspase 3; Cell Adhesion; Cell Differentiation; Cell Line, Tumor; Cell Lineage; Cell Proliferation; Cell Survival; Connexin 43; Escherichia coli; Fluorocarbons; Gap Junctions; Inhibitory Concentration 50; Mice; Neurons; Reactive Oxygen Species; RNA, Messenger; Spheroids, Cellular; Tretinoin

Morris hepatoma 7800C1 cells (a Wistar rat cell line) were exposed to 100 microM arachidonic acid in the medium for seven days. This treatment resulted in 150% and 60% increases (above control activities) in acyl-CoA oxidase (which catalyzes the first step in peroxisomal beta-oxidation) and catalase activities, respectively. Arachidonic acid (C20:4) can be metabolized to 20- and 19-hydroxy-arachidonic acid by cytochrome P-450IVA and it was shown that our cells are capable of forming 20-hydroxyarachidonic acid. However, 20-hydroxyarachidonic acid (0.1-0.8 microM, 4 days) had no effects on lauroyl-CoA oxidase and catalase activities in Morris hepatoma cells. Treatment of 7800C1 cells with 100 microM all-trans-retinoic acid resulted in inductions of catalase (160% above the control activity) and carnitine acetyltransferase (140% above the control activity) activities. The activity of lauroyl-CoA oxidase was often, but not always, slightly induced by treatment with all-trans-retinoic acid. When all-trans-retinoic acid was administered together with arachidonic acid, these two compounds had a synergistic effect on the induction of acyl-CoA oxidase activity (almost 700% above the control activity). However, treatment of Morris hepatoma cells with the man-made peroxisome proliferator, perfluorooctanoic acid, together with all-trans-retinoic acid did not result in any synergistic effect on this same enzyme activity. In summary, this study (1) corroborates findings from transfection experiments indicating that the heterodimer PPAR-RXR alpha activates transcription of the acyl-CoA oxidase gene using the Morris hepatoma cell line; (2) shows that arachidonic acid induces the activity of lauroyl-CoA oxidase; (3) suggests that transcription of the catalase gene is not regulated by a PPAR-RXR alpha heterodimer in this system; and (4) demonstrates that peroxisome proliferation in Morris hepatoma cells by perfluorooctanoic acid is not as dependent on the level of retinoic acid as is the same process caused by arachidonic acid.

Topics: Acyl-CoA Oxidase; Animals; Arachidonic Acid; Caprylates; Carnitine O-Acetyltransferase; Catalase; Cytochrome P-450 CYP4A; Cytochrome P-450 Enzyme System; Enzyme Induction; Fluorocarbons; Hydroxyeicosatetraenoic Acids; Immunoblotting; Liver Neoplasms, Experimental; Microbodies; Mixed Function Oxygenases; Oxidoreductases; Rats; Rats, Wistar; Receptors, Retinoic Acid; Retinoid X Receptors; Transcription Factors; Tretinoin; Tumor Cells, Cultured