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Dietary lignin, an insoluble fiber, enhanced uterine cancer but did not influence mammary cancer induced by N-methyl-N-nitrosourea in rats

Birt, D.F., Markin, R.S., Blackwood, D., Harvell, D.M.E., Shull, J.D., Pennington, K.L.
Nutrition and cancer 1998 v.31 no.1 pp. 24-30
lignin, breast neoplasms, uterine diseases, adenocarcinoma, carcinogenesis, incidence, diet, experimental diets, food intake, body weight, blood serum, estradiol, N-methyl-N-nitrosourea, gene expression, creatine kinase, uterus, weight, disease prevention, rats, animal models, dietary fiber, duration, females
Previous investigations suggested potential breast cancer-preventive properties of dietary fiber from cabbage. The purpose of the present investigation was to determine whether lignin, a component of cabbage fiber, would protect against mammary carcinogenesis by N-methyl-N-nitroso-urea (MNU) in Sprague-Dawley rats. A six-week study was conducted using diets containing 0.5-5% dietary wood lignin (a readily available, purified source). These diets were well tolerated by the rats, and a carcinogenesis study using 5 mg MNU/100 g body wt iv at 50 days of age was conducted, with the 2.5% lignin diet fed from 6 through 8 weeks of age followed by 5% lignin diet until 20 weeks after MNU. Dietary lignin and MNU treatment increased food consumption (p < 0.05), and body weight was slightly reduced at 10 and 20 weeks after MNU in the MNU-5% lignin diet group (p < 0.05). Serum estradiol was not altered by dietary lignin or MNU treatment, but uterine weights were highest in the MNU-control diet group 4 and 12 weeks after MNU. Expression of creatine kinase B, an estrogen-responsive gene, was lower in the uteri of the MNU-lignin diet group than in other groups at 20 weeks. Mammary carcinogenesis was not altered by dietary lignin. However, uterine endometrial adenocarcinoma was observed only in the MNU-lignin diet group (4 carcinomas/40 effective rats) (p < 0.05).