Suppression of Mammary Carcinogenesis Through Early Exposure to Dietary Lipotropes Occurs Primarily In Utero.

The study determined whether feeding during lactation affects the suppressive effect of maternal dietary lipotropes (i.e., methionine, choline, folate, and vitamin B-12) on mammary carcinogenesis. Pregnant Sprague-Dawley rats were randomly allocated to the control diet during pregnancy and lactation (CC), lipotropes-fortified diet during pregnancy (LC), lipotropes-fortified diet during pregnancy plus lactation (LL), or lipotropes-fortified diet during lactation (CL). Randomly selected female offspring from each group were injected intraperitoneally with 50 mg/kg body weight of N-nitroso-N-methylurea at 50 days of age to induce mammary tumors. The LC and LL diets significantly increased tumor latency and survival (P < 0.05). Tumor volumes were significantly suppressed in LC and LL offspring as compared with the CC and CL pups (3759.1 +/- 563.0 and 3603.7 +/- 526.1 vs. 7465.0 +/- 941.1 and 5219.3 +/- 759.8 mm(3), respectively; P < 0.05). Both LC and LL lowered tumor multiplicity as compared with CC and CL (P < 0.05). The LC and LL diets repressed transcription of histone deacetylase (HDAC) 1 as well as total HDAC enzyme activity as compared with CC and CL diets (P < 0.05). Data suggest that the tumor suppressive effect of maternal dietary lipotropes is primarily in utero and may be linked to regulation of proteins involved in chromatin remodeling.