Display options
Share it on

Genes Nutr. 2012 Oct;7(4):549-58. doi: 10.1007/s12263-012-0294-6. Epub 2012 Apr 24.

Dietary soy protein induces hepatic lipogenic enzyme gene expression while suppressing hepatosteatosis in obese female Zucker rats bearing DMBA-initiated mammary tumors.

Genes & nutrition

Reza Hakkak, Ahmed Al-Dwairi, George J Fuchs, Soheila Korourian, Frank A Simmen

Affiliations

  1. Department of Dietetics and Nutrition, University of Arkansas for Medical Sciences, 4301 W. Markham St., Mail Slot 627, Little Rock, AR, 72205, USA, [email protected].

PMID: 22528625 PMCID: PMC3448032 DOI: 10.1007/s12263-012-0294-6

Abstract

Fatty liver is associated with obesity and breast cancer. We used an obese rat model of mammary cancer to examine whether hepatosteatosis is modifiable by diet and associated with altered expression of hepatic lipogenic enzyme genes, thyroid hormone system genes and cholesterol metabolism-related genes. Beginning at the age of 5 weeks, lean and obese female Zucker rats were fed high-isoflavone soy protein- or casein (control protein)-containing diets. Rats were euthanized at 200 days of age [corresponding to 147 days after administration of carcinogen to induce mammary tumors; (Hakkak et al. in, Oncol Lett 2:29-36, 2011)]. Obese rats had a greater degree of liver steatosis than lean rats. Obese casein-fed rats had marked steatosis with small foci of mononuclear infiltration, whereas obese soy protein-fed rats had a significantly lower steatosis index. Comparisons between lean and obese casein-fed rats showed that obesity was associated with significant reductions in hepatic mRNA abundance for Glucose 6-Phosphate Dehydrogenase (G6PD), 6-Phosphogluconate Dehydrogenase (6PGD), Thyroid Receptor Alpha 1 (TRα1), Thyroid Receptor Beta 1 (TRβ1) and Iodothyronine Deiodinase 1 (DIO1). The soy protein diet was associated with increased expression of Fatty Acid Synthase (FASN), Malic Enzyme 1 (ME1), 6PGD, Sterol Regulatory Element Binding Protein-1c (SREBP-1c) and SREBP-2 genes in the livers of obese but not lean rats. Western blot analysis showed a significant induction of ME1 protein expression in the livers of obese, soy protein-fed rats, which paralleled the increased serum insulin level in this group. Long-term soy protein consumption can counter hepatic steatosis while coincidently promoting hepatic lipogenic gene expression, the latter likely a consequence of elevated serum insulin. We suggest that elevations in serum insulin, hepatic lipogenesis and cholesterol synthesis all contributed to the increased tumorigenesis previously observed for the obese, soy protein-fed rats.

References

  1. World J Gastroenterol. 2003 Jul;9(7):1618-20 - PubMed
  2. J Nutr. 2002 Sep;132(9):2562-9 - PubMed
  3. Hepatology. 2004 Dec;40(6):1387-95 - PubMed
  4. J Lipid Res. 2010 Mar;51(3):500-13 - PubMed
  5. Oncol Lett. 2011 Jan;2(1):29-36 - PubMed
  6. Science. 1996 Feb 16;271(5251):994-6 - PubMed
  7. Cell. 1995 Dec 29;83(7):1263-71 - PubMed
  8. Ann Hepatol. 2002 Jan-Mar;1(1):12-9 - PubMed
  9. JAMA. 2003 Jan 1;289(1):76-9 - PubMed
  10. Genome Biol. 2002 Jun 18;3(7):RESEARCH0034 - PubMed
  11. J Nutr Biochem. 2010 Nov;21(11):1106-13 - PubMed
  12. Int J Obes Relat Metab Disord. 2001 Feb;25(2):296-8 - PubMed
  13. J Clin Invest. 1996 Sep 15;98(6):1277-82 - PubMed
  14. J Hepatol. 2007 Jun;46(6):1133-42 - PubMed
  15. Med Oncol. 2007;24(4):367-71 - PubMed
  16. J Nutr. 2004 Jun;134(6):1320-7 - PubMed
  17. Gastroenterology. 2005 Jul;129(1):375-8 - PubMed
  18. Nutrition. 2009 May;25(5):574-80 - PubMed
  19. Vitam Horm. 1989;45:1-125 - PubMed
  20. Am J Clin Nutr. 2005 Feb;81(2):397-408 - PubMed
  21. Clin Liver Dis. 2007 Feb;11(1):1-16, vii - PubMed
  22. Br J Nutr. 2005 Sep;94(3):321-30 - PubMed
  23. J Lipid Res. 2005 Sep;46(9):1823-32 - PubMed
  24. Cancer Epidemiol Biomarkers Prev. 2000 Jan;9(1):113-7 - PubMed
  25. N Engl J Med. 1995 Aug 3;333(5):276-82 - PubMed
  26. Br J Nutr. 2006 Aug;96(2):249-57 - PubMed
  27. J Nutr. 2003 May;133(5):1238-43 - PubMed
  28. J Nutr. 2004 Mar;134(3):522-9 - PubMed
  29. Cancer Lett. 2005 Jun 16;224(1):45-52 - PubMed
  30. J Nutr. 2008 Mar;138(3):462-8 - PubMed
  31. Breast Cancer Res Treat. 2003 Jan;77(2):171-83 - PubMed
  32. J Lipid Res. 1972 Mar;13(2):234-43 - PubMed
  33. Nat Genet. 2009 Apr;41(4):415-23 - PubMed
  34. Am J Med. 2002 Dec 30;113 Suppl 9B:71S-88S - PubMed
  35. J Nutr. 1963 May;80:6-19 - PubMed
  36. Eur J Biochem. 1978 Sep 1;89(2):329-39 - PubMed

Publication Types

Grant support