Metabolic fate and effects of saturated and unsaturated fatty acids in Hep2 human larynx tumor cells.
Previous studies have reported the presence of carnitine palmitoyltransferase I and II in tumor cells and the inhibitory effects of fatty acids on cell proliferation. The present work considered the metabolic fate of [14C] or [3H]-labeled fatty acids and their effects on cellular metabolism in Hep2 human larynx tumor cells. The rate of uptake of acetate was 45% of that of myristate, palmitate, oleate, linoleate and arachidonate. However, acetate was rapidly metabolized within the cell as seen by its low rate of accumulation as non-esterified fatty acid, < 5% of that of the other fatty acids. The incorporation of fatty acids into neutral lipid fractions showed palmitate and oleate primarily entered the phospholipid fraction, while linoleate and arachidonate entered equally the phospholipid and triacylglycerol fractions. Palmitate and oleate were oxidized to 14CO2 at higher rates than linoleate and arachidonate, with arachidonate being the least oxidized of the unsaturated fatty acids. Acetate was oxidized at 10-30 fold higher rates than the other fatty acids. Palmitate, oleate, linoleate and arachidonate all had significant inhibitory effects on the rate of glucose utilization by Hep2 cells, ranging from 25-38% inhibition and were found to inhibit cell proliferation by 17-73%. These findings suggest that certain fatty acids not only play a structural role in cellular metabolism, but may also have a potential regulatory role in the glycolytic pathway of Hep2 cells.
Colquhoun
A
A
Department of Physiology and Biophysics, University of São Paulo, Brazil. Alison@bmb.icb1.usp.br
Curi
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R
D005227:Fatty Acids / Q000378:metabolism*; D005231:Fatty Acids, Unsaturated / Q000378:metabolism*; D005947:Glucose / Q000378:metabolism; D006801:Humans; D007830:Larynx / Q000166:cytology; D010084:Oxidation-Reduction; D014407:Tumor Cells, Cultured
D005227:Fatty Acids; D005231:Fatty Acids, Unsaturated; D005947:Glucose