TY - JOUR
T1 - The combination of green tea and tamoxifen is effective against breast cancer
AU - Sartippour, Maryam R.
AU - Pietras, Richard
AU - Marquez-Garban, Diana C.
AU - Chen, Hsiao Wang
AU - Heber, David
AU - Henning, Susanne M.
AU - Sartippour, Guilan
AU - Zhang, Liping
AU - Lu, Ming
AU - Weinberg, Olga
AU - Rao, Jian Yu
AU - Brooks, Mai N.
N1 - Funding Information:
This Research was performed at the University of California Los Angeles Medical Center, Los Angeles, CA, USA. This study was supported by the California Breast Cancer Research Program and the Stiles Program in Integrative Oncology (R.P., D.C.M., H.W.C. and O.W.). M.R.S. was supported by an American Cancer Society training grant.
PY - 2006/12
Y1 - 2006/12
N2 - Epidemiologic data have suggested that green tea may prevent breast cancer. Studies in our laboratory have provided evidence that green tea extract inhibits breast cancer growth by a direct anti-proliferative effect on the tumor cells, as well as by indirect suppressive effects on the tumor-associated endothelial cells. In this study, we asked whether concurrent administration of green tea may add to the anti-tumor effects of standard breast cancer therapy. We observed that green tea increased the inhibitory effect of tamoxifen on the proliferation of the ER (estrogen receptor)-positive MCF-7, ZR75, T47D human breast cancer cells in vitro. This combination regimen was also more potent than either agent alone at increasing cell apoptosis. In animal experiments, mice treated with both green tea and tamoxifen had the smallest MCF-7 xenograft tumor size, and the highest levels of apoptosis in tumor tissue, as compared with either agent administered alone. Moreover, the suppression of angiogenesis in vivo correlated with larger areas of necrosis and lower tumor blood vessel density in treated xenografts. Green tea decreased levels of ER-α in tumors both in vitro and in vivo. We also observed that green tea blocked ER-dependent transcription, as well as estradiol-induced phosphorylation and nuclear localization of mitogen-activated protein kinase. To our knowledge, this study is the first to show the interaction of green tea with the ER pathway, as well as provide mechanistic evidence that the combination of green tea and tamoxifen is more potent than either agent alone in suppressing breast cancer growth. These results may lead to future improvements in breast cancer treatment and prevention.
AB - Epidemiologic data have suggested that green tea may prevent breast cancer. Studies in our laboratory have provided evidence that green tea extract inhibits breast cancer growth by a direct anti-proliferative effect on the tumor cells, as well as by indirect suppressive effects on the tumor-associated endothelial cells. In this study, we asked whether concurrent administration of green tea may add to the anti-tumor effects of standard breast cancer therapy. We observed that green tea increased the inhibitory effect of tamoxifen on the proliferation of the ER (estrogen receptor)-positive MCF-7, ZR75, T47D human breast cancer cells in vitro. This combination regimen was also more potent than either agent alone at increasing cell apoptosis. In animal experiments, mice treated with both green tea and tamoxifen had the smallest MCF-7 xenograft tumor size, and the highest levels of apoptosis in tumor tissue, as compared with either agent administered alone. Moreover, the suppression of angiogenesis in vivo correlated with larger areas of necrosis and lower tumor blood vessel density in treated xenografts. Green tea decreased levels of ER-α in tumors both in vitro and in vivo. We also observed that green tea blocked ER-dependent transcription, as well as estradiol-induced phosphorylation and nuclear localization of mitogen-activated protein kinase. To our knowledge, this study is the first to show the interaction of green tea with the ER pathway, as well as provide mechanistic evidence that the combination of green tea and tamoxifen is more potent than either agent alone in suppressing breast cancer growth. These results may lead to future improvements in breast cancer treatment and prevention.
UR - http://www.scopus.com/inward/record.url?scp=33845363659&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=33845363659&partnerID=8YFLogxK
U2 - 10.1093/carcin/bgl066
DO - 10.1093/carcin/bgl066
M3 - Article
C2 - 16785249
AN - SCOPUS:33845363659
SN - 0143-3334
VL - 27
SP - 2424
EP - 2433
JO - Carcinogenesis
JF - Carcinogenesis
IS - 12
ER -