Black tea polyphenol theaflavins inhibit aromatase activity and attenuate tamoxifen resistance in HER2/neu-transfected human breast cancer cells through tyrosine kinase suppression.

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Title:	Black tea polyphenol theaflavins inhibit aromatase activity and attenuate tamoxifen resistance in HER2/neu-transfected human breast cancer cells through tyrosine kinase suppression.
Authors:	魏宗德;(Lee HH);高銘欽(Ming-Ching Kao);(Lin JK)
Contributors:	醫學院生物科技學系
Keywords:	Black tea polyphenols;Aromatase;Breast cancer;HER2/neu;Hormonal resistance
Date:	2004-09
Issue Date:	2009-08-21 11:03:42 (UTC+8)
Abstract:	The aromatase enzyme, which converts androstenedione to oestrone, regulates the availability of oestrogen to support the growth of hormone-dependent breast tumours. In this study, we investigated the inhibitory effects of black tea polyphenols on aromatase activities. We found that black tea polyphenols, TF-1, TF-2 and TF-3, significantly inhibited rat ovarian and human placental aromatase activities. In addition, using an in vivo model, these black tea polyphenols also inhibited the proliferation induced by 100 nM dehydroepiandrosterone (DHEA) in MCF-7 cells. Transfection of HER2/neu in MCF-7 breast cancer cells appeared to be associated with an increased resistance of the cells to hormonal therapy. Interestingly, unlike the selective oestrogen receptor modulator (SERM) tamoxifen, black tea polyphenols had antiproliferation effects in breast cancer cells with hormonal resistance. The inhibitory effect of black tea polyphenols on hormone-resistant breast cancer cells suppressed the basal receptor tyrosine phosphorylation in HER2/neu-overexpressing MCF-7 cells. These findings suggest the use of black tea polyphenols may be beneficial in the chemoprevention of hormone-dependent breast tumours and represent a possible remedy to overcome hormonal resistance of hormone-independent breast tumours.
Relation:	EUROPEAN JOURNAL OF CANCER40(14):2165~2174
Appears in Collections:	[Department of Biological Science and Technology] Journal articles

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