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KMID : 0620920090410060371
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Experimental & Molecular Medicine
2009 Volume.41 No. 6 p.371 ~ p.380
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Isoflavone-deprived soy peptide suppresses mammary tumorigenesis by inducing apoptosis
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Park Kyoung-Sook
Choi Kyu-Sam
Kim Hye-Mee
Kim Kwang-Bae
Lee Mi-Hee
Lee Je-Ho
Rim Kim Jean-Chinock
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Abstract
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During carcinogenesis, NF-κB mediates processes associated with deregulation of the normal control of proliferation, angiogenesis, and metastasis. Thus, suppression of NF-κB 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 IκB kinase (IKK) complex that plays a central role in NF-κB 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[α]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-κB 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.
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KEYWORD
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apoptosis, breast neoplasms, chemoprevention, HSP90 heat-shock proteins, isoflavones, NF-κB, soybean proteins
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