The role of cell adhesion molecules has been studied extensively in the process of inflammation, and these molecules are critical components of carcinogenesis and cancer metastasis. This study investigated the effect of tanshinone I derived from the traditional herbal medicine, Salvia miltiorrhiza Bunge, on the expression of intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) in tumor necrosis factor-alpha (TNF-alpha)-stimulated endothelial cells. Furthermore, this study investigated the effect of tanshinone I on cancer growth, invasion and angiogenesis on human breast cancer cells MDA-MB-231, both in vitro and in vivo. Tanshinone I dose dependently inhibited ICAM-1 and VCAM-1 expressions in human umbilical vein endothelial cells (HUVECs) that were stimulated with TNF-alpha for 6 h. Pretreatment with tanshinone I significantly reduced adhesion of either monocyte U937 or MDA-MB-231 cells to HUVECs. Interestingly, the inhibitory effect of tanshinone I on monocyte and cancer cell adhesion to HUVECs was mimicked by transfection with ICAM-1 and VCAM-1 small interfering RNA. In addition, tanshinone I effectively inhibited TNF-alpha-induced production of vascular endothelial growth factor (VEGF) and VEGF-mediated tube formation in HUVECs. Tanshinone I also inhibited TNF-alpha-induced VEGF production in MDA-MB-231 cells and migration of MDA-MB-231 cells through extracellular matrix. Additionally, reduction of tumor mass volume and decrease of metastasis incidents by tanshinone I were observed in vivo. In conclusion, this study provides a potential mechanism for the anticancer effect of tanshinone I on breast cancer cells, suggesting that tanshinone I may serve as an effective drug for the treatment of breast cancer.

Abstract. Danshen (Salvia miltiorrhiza Bunge) is a herb that has been widely and successfully used for treating inflammatory diseases in clinics in Asia. The relatively abundant tanshinones, tanshinone I, tanshinone IIA, cryptotanshinone, and dihydrotanshinone, have been isolated from Danshen. These tanshinones are the major diterpenes isolated from Danshen, and show cytotoxic effects on cell lines derived from human carcinomas of the colon, ovary, lung, mouth, and breast. Recently, anti-cancer activities of tanshinone IIA have been reported, which suggest that the structurally similar tanshinone I may possess similar cytotoxic effects on tumor cells. We investigated the effect of tanshinone I on the induction of apoptosis in human breast cancer cells (MCF-7 and MDA-MB-231) in vitro. Tanshinone I inhibited cell proliferation of MCF-7 and MDA-MB-231 cells in a doseand time-dependent manner, as assayed by MTT. In addition, TUNEL assay and flow cytometry showed that tanshinone I significantly induced apoptosis in MCF-7 and MDA-MB-231 cells. The induction of apoptotic cell death was mediated by the activation of caspase 3, the downregulation of the level of the anti-apoptotic protein, Bcl-2, and the upregulation of the level of the pro-apoptotic protein, Bax. Taken together, these results reveal a potential mechanism for the anti-cancer effect of tanshinone I on human breast cancer cells, and suggest that tanshinone I may serve as an effective adjunctive reagent in the treatment of human breast cancer.

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Wogonin is a plant monoflavonoid which has been reported to inhibit cell growth and/or induce apoptosis in various tumors. Herein, we investigated the in vitro and in vivo anticancer effects and associated mechanisms of wogonin in human breast cancer. Effects of wogonin were examined in estrogen receptor (ER)-positive and -negative human breast cancer cells in culture for proliferation, cell cycle progression, and apoptosis. The in vivo effect of oral wogonin was examined on tumor xenograft growth in athymic nude mice. The molecular changes associated with the biological effects of wogonin were analyzed by immunoblotting. Cell growth was attenuated by wogonin (50-200 lM), independently of its ER status, in a time-and concentration-dependent manner. Apoptosis was enhanced and accompanied by upregulation of PARP and Caspase 3 cleavages as well as proapoptotic Bax protein. Akt activity was suppressed and reduced phosphorylation of its substrates, GSK-3b and p27, was observed. Suppression of Cyclin D1 expression suggested the downregulation of the Akt-mediated canonical Wnt signaling pathway. ER expression was downregulated in ER-positive cells, while c-ErbB2 expression and its activity were suppressed in ER-negative SK-BR-3 cells. Wogonin feeding to mice showed inhibition of tumor growth of T47D and MDA-MB-231 xenografts by up to 88% without any toxicity after 4 weeks of treatment. As wogonin was effective both in vitro and in vivo, our novel findings open the possibility of wogonin as an effective therapeutic and/or chemopreventive agent against both ERpositive and -negative breast cancers, particularly against the more aggressive and hormonal therapy-resistant ER-negative types. ' 2007 Wiley-Liss, Inc.

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