Evidence for the involvement of polyunsaturated fatty acids in the regulation of long-chain acyl CoA thioesterases and peroxisome proliferation in rat carcinosarcoma.
The feeding of high-fat diets rich in polyunsaturated fatty acids (PUFAs) caused a marked increase in the acyl CoA thioesterase activity of the Walker 256 tumour. Diets containing lower levels of PUFAs did not alter the activity of acyl CoA thioesterase and the exposure of LLC-WRC256 tumour cells, in culture, to PUFAs (150 microM) also was ineffective in altering activity. The tumours from n-3 PUFA-rich and control diets were analysed by transmission electron microscopy in order to compare peroxisomal content. The presence of PUFAs led to an almost 10-fold increase in the number of peroxisomes present in the tumour tissue. A common feature of the PUFA-treated tumour was the presence of many cells containing highly condensed heterochromatin at the periphery of the nucleus, indicative of apoptosis. The sparsity of endoplasmic reticulum and the lack of detection of mitochondrial acyl CoA thioesterase, MTE-I, led to the conclusion that the increase in tumour acyl CoA thioesterase activity may be due to an increase in the activity of the peroxisomal enzyme.
Departamento de Histologia e Embriologia, Instituto de Ciências Biomédicas, Universidade de São Paulo, Brasil.
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Ramos
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Colquhoun
D000818:Animals; D017209:Apoptosis; D002296:Carcinosarcoma / Q000201:enzymology / Q000378:metabolism*; D002455:Cell Division; D002467:Cell Nucleus / Q000378:metabolism; D003065:Coenzyme A / Q000378:metabolism*; D004721:Endoplasmic Reticulum / Q000378:metabolism; D005231:Fatty Acids, Unsaturated / Q000378:metabolism*; D008401:Gas Chromatography-Mass Spectrometry; D006570:Heterochromatin / Q000378:metabolism; D008297:Male; D008854:Microscopy, Electron; D009374:Neoplasms, Experimental; D010171:Palmitoyl Coenzyme A / Q000378:metabolism; D010170:Palmitoyl-CoA Hydrolase / Q000378:metabolism*; D020025:Peroxisome Proliferators / Q000378:metabolism*; D020675:Peroxisomes / Q000378:metabolism / Q000648:ultrastructure; D051381:Rats; D017208:Rats, Wistar; D014407:Tumor Cells, Cultured
D005231:Fatty Acids, Unsaturated; D006570:Heterochromatin; D020025:Peroxisome Proliferators; D010171:Palmitoyl Coenzyme A; D010170:Palmitoyl-CoA Hydrolase; D003065:Coenzyme A