Membrane fatty acid composition and radiation response of Bp8 sarcoma ascites tumour cells

The radiation response of Bp8 sarcoma ascites tumour cells with differences in membrane fatty acid composition was studied. The cells were grown i.p. in NMRI mice and their membrane composition was changed in response to different dietary regimes provided to the host animals. Three diets that differed only with regard to the source of fatty acids, i.e. sunflower seed oil, coconut oil, hydrogenated lard and a fourth commercially available standard laboratory diet, were given to the mice for different lengths of time, before implantation of the tumour cells. The time course for the dietary regimes to induce different levels of changes in membrane fatty acid composition of the ascites cells was established. The evaluation of the radiosensitivity of cells with different membrane fatty acid composition was done in vitro. Cell survival, expressed by D0, varied only insignificantly between the four dietary groups, while their repair capacity (Dq and n) differed significantly. Increased repair capacity was observed for ascites cells grown in animals on diets enriched in sunflower seed oil and coconut oil, compared with cells from mice fed the hydrogenated lard diet or from cells from the control animals. The membrane fatty acid composition of the cells from the two dietary groups with increased levels of repair capacity differed extensively, and in general there was no correlation observed between radiation response and the membrane fatty acid composition of the four dietary groups studied. For two of the dietary groups, coconut oil and control, with marked differences in membrane fatty acid composition, the effects of irradiation on ascites tumour growth rate and cell cycle distribution were followed in vivo. For none of these parameters was an effect of membrane fatty acid composition on radiation response observed.