Exp Mol Med.  2009 Jun;41(6):371-380. 10.3858/emm.2009.41.6.042.

Isoflavone-deprived soy peptide suppresses mammary tumorigenesis by inducing apoptosis

• Park K
• Choi K
• Kim H
• Kim K
• Lee MH
• Lee JH
• Kim Rim JC

• KMID: 756229
• DOI: http://doi.org/10.3858/emm.2009.41.6.042

Abstract

During carcinogenesis, NF-kappaB mediates processes associated with deregulation of the normal control of proliferation, angiogenesis, and metastasis. Thus, suppression of NF-kappaB has been linked with chemoprevention of cancer. Accumulating findings reveal that heat shock protein 90 (HSP90) is a molecular chaperone and a component of the IkappaB kinase (IKK) complex that plays a central role in NF-kappaB activation. HSP90 also stabilizes key proteins involved in cell cycle control and apoptosis signaling. We have determined whether the exogenous administration of isoflavone-deprived soy peptide prevents 7,12-dimethylbenz[alpha]anthracene (DMBA)-induced rat mammary tumorigenesis and investigated the mechanism of action. Dietary administration of soy peptide (3.3 g/rat/day) significantly reduced the incidence of ductal carcinomas (50%), the number of tumors per multiple tumor-bearing rats (49%; P < 0.05), and extended the latency period of tumor development (8.07 +/- 0.92 weeks) compared to control diet animals (10.80 +/- 1.30; P < 0.05). Our results have further demonstrated that soy peptide (1) dramatically inhibits the expression of HSP90, thereby suppressing signaling pathway leading to NF-kappaB activation; (2) induces expression of p21, p53, and caspase-3 proteins; and (3) inhibits expression of VEGF. In agreement with our in vivo data, soy peptide treatment inhibited the growth of human breast MCF-7 tumor cells in a dose-dependent manner and induced apoptosis. Taken together, our in vivo and in vitro results suggest chemopreventive and tumor suppressive functions of isoflavone-deprived soy peptide by inducing growth arrest and apoptosis.

Keyword

apoptosis; breast neoplasms; chemoprevention; HSP90 heat-shock proteins; isoflavones; NF-kappaB; soybean proteins

MeSH Terms

9,10-Dimethyl-1,2-benzanthracene
Adenocarcinoma/*prevention & control
Animals
Apoptosis/*drug effects
Breast Neoplasms/chemically induced/pathology/*prevention & control
Cell Line, Tumor
Chemoprevention
Female
Gene Expression Regulation, Neoplastic
HSP90 Heat-Shock Proteins/genetics/metabolism
Humans
Isoflavones/chemistry
NF-kappa B/genetics/metabolism
Peptides/chemistry/isolation & purification/therapeutic use
Rats
Rats, Sprague-Dawley
Soybean Proteins/chemistry/*isolation & purification/*therapeutic use
Soybeans/chemistry