Structural analysis of phosphatidylcholines of Yoshida ascites hepatoma and liver cells from host rats fed a control and an essential fatty acid-deficient diet

Abstract

In order to study the effect of a dietetic manipulation on the phospholipid molecular structure of a poorly differentiated tumor, the phosphatidylcholines from Yoshida hepatoma cells (AH130) grown either in essential fatty acid deficient or control rats were analyzed comparatively to those from the host livers. Due to essential fatty acid deficiency, the host rat liver exhibited an increased level of mono-unsaturated 1,2-diacyl-sn-glycero-3-phosphocholines, a reduced level of the species contained linoleic acid, and the substitution of tetra- and polyunsaturated-1,2-diacyl-sn-glycero-3-phosphocholines with equivalent amounts of species containing eicosatrienoic acid. The structural analysis of the phosphatidylcholines from Yoshida hepatoma cells grown either in control or essential fatty acid deficient rats revealed the occurrence of 1-alkyl-2-acyl- together with 1,2-diacyl-sn-glycero-3-phosphocholines. The alkyl chains of ether-linked phosphatidylcholines were mainly constituted by 18 : 1, while the acyl chains were characterized by a high level of linoleic and arachidonic or eicosatrienoic acids. The 1,2-diacyl-sn-glycero-3-phosphocholines of the Yoshida hepatoma cells grown in control rats, when compared to those of the liver, showed a higher level of 1,2-disaturated, an increased proportion of mono-unsaturated and a lower proportion of tetra- and polyunsaturated species. In addition, the hepatoma cells showed the occurrence of high proportions of reverse isomeric and random species, such as 1-oleoyl-2-palmitoyl-, 1,2-dioleoyl-, 1-oleoyl-2-linoleoyl- and 1-linoleoyl-2-oleoyl-sn-glycero-3-phosphocholines, scarcely represented in the liver. Growth of Yoshida hepatoma cells in essential fatty acid deficient rats resulted in :(i) the disappearence of 1,2-diacyl-sn-glycero-3-phosphocholines containing linoleic acid; (ii) the substitution of tetra- and and polyunsaturated 1,2-diacyl-sn-glycero-3-phosphocholines with small quantities of species containing eicosatrienoic acid; (iii) an increase of of monounsaturated species, mainly 1-stearoyl-2-oleoyl- and 1-palmitoyl-2-palmitoleoyl-sn-glycero-3-phosphocholines; (iv) a remarkable increase of 1,2-dioleoyl-sn-1,2-dioleoyl-sn-glycero-3-phosphocholine.