Mechanisms associated with dose-dependent inhibition of rat mammary carcinogenesis by dry bean (Phaseolus vulgaris, L.)

J Nutr. 2008 Nov;138(11):2091-7. doi: 10.3945/jn.108.094557.

Abstract

The purpose of this study was to determine whether a dry bean (Phaseolus vulgaris, L.) containing diet exerts an inhibitory effect on mammary carcinogenesis in a well-characterized rodent model for breast cancer. Twenty-one-d-old female Sprague Dawley rats were given an intraperitoneal injection of 1-methyl-1-nitrosourea and 7 d after carcinogen injection were randomized to 1 of 5 groups fed a modification of the AIN-93G diet formulation containing 0, 7.5, 15, 30, or 60% (wt:wt) small red dry bean incorporated as cooked, freeze-dried, and milled powder. All experimental diets had the same macronutrient content based on proximate analysis. Compared with the control group, dry bean consumption resulted in dose-dependent reductions in mammary cancer incidence (P = 0.046), cancer multiplicity (P = 0.001), and tumor burden (P = 0.01). Dry bean consumption was associated with dose-dependent reductions in plasma concentrations of glucose, insulin, insulin-like growth factor-1, C-reactive protein, and interleukin-6 in food-deprived rats. Analysis of mammary adenocarcinomas indicated that a dominant mechanism accounting for reduced tumor burden was the induction of apoptosis. B cell lymphoma 2 and X-linked inhibitor of apoptosis protein levels decreased and BCL-2-associated X protein increased with increasing dry bean consumption, findings consistent with the induction of apoptosis via the mitochondrial pathway. These data demonstrate that a legume without noteworthy content of isoflavones inhibits the development of mammary carcinogenesis and are consistent with a recent report from the Nurses Health Study that bean or lentil intake is associated with a lower risk for breast cancer.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Animal Feed
  • Animals
  • Apoptosis
  • Cell Proliferation
  • Diet
  • Dose-Response Relationship, Drug
  • Female
  • Mammary Neoplasms, Animal / chemically induced*
  • Mammary Neoplasms, Animal / prevention & control*
  • Methylnitrosourea / toxicity
  • Phaseolus / metabolism*
  • Rats
  • Rats, Sprague-Dawley

Substances

  • Methylnitrosourea