Enhancement of 2-acetylaminofluorene liver carcinogenesis in rats fed a choline-devoid diet.

The effects of feeding a choline-devoid (CD) or a choline-supplemented (CS) diet on the induction of liver tumors in rats by 2-acetylaminofluorene (AAF) were investigated. Male Sprague-Dawley rats were fed either a CD or a CS diet containing 0.0075% AAF. Three to eight animals were killed 1, 3, 4 and 6 months thereafter. Well to moderately well differentiated hepatocellular carcinomas developed in 50% and 75% of rats fed the CD + AAF diet for 4 and 6 months, respectively. Cholangiocarcinomas developed, after 6 months, in 38% of the animals. No tumor developed in rats fed the CS + AAF diet. The results extend to AAF those previously obtained with DL-ethionine and azaserine showing that feeding a CD diet greatly potentiates the induction in rats of liver tumors by chemical carcinogens.