The effect of
dietary fat concentration and saturation on high energy
phosphate metabolites and
phospholipid turnover in transplanted line 168 murine mammary
tumors was studied using surface coil 31P-nuclear magnetic resonance spectroscopy. Female BALB/c mice were fed one of five diets each containing at least the minimum of
essential fatty acids (EFA). Four diets contained additional safflower or
palm oil for a total fat concentration of 5 or 20% by weight. The growth rate of
tumors from mice fed the high
safflower oil diet was significantly greater than the growth rate of
tumors for mice fed all other diets including the one which contained the minimal EFA. 31P-nuclear magnetic resonance-observable
phosphate metabolite ratios.
ATP/Pi,
ATP/phosphomonoester (
ATP/PME), and PME/Pi, and
tumor pH of line 168
tumors decreased with increasing
tumor volume, indicating a shift from active to inactive
tumor metabolism. The rates of those decreases with progressive
tumor growth differed significantly among
tumors of mice fed the different diets. Decreases in
ATP/Pi,
ATP/PME, and pH were the most rapid in the
tumors of mice fed the high
safflower oil diet and significantly faster than
tumors of mice fed the diet containing minimum EFA. In addition, the decrease in the PME/Pi ratio of
tumors was significantly greater in mice fed the high fat (high
palm oil and high
safflower oil) diets than mice fed the diet containing the minimum of EFA. The rate of decline of
ATP/Pi and
ATP/PME with progressive
tumor growth was directly correlated with levels of
linoleic acid as well as total
unsaturated fat. High levels of a polyunsaturated fat had a significant effect on mammary
tumor metabolism particularly during early stages of
tumor growth. Differences in high energy
phosphate metabolite dynamics relative to
dietary fat were present in
tumors of equal volume. Thus,
dietary fat influences on mammary
tumorigenesis may be related to high energy
phosphate metabolites.