Epigallocatechin-3-gallate inhibits activation of HER-2/neu and downstream signaling pathways in human head and neck and breast carcinoma cells.
Overexpression of the HER-2/neu receptor (HER-2) is associated with a poor prognosis in patients with breast carcinoma and also in patients with head and neck squamous cell carcinoma (HNSCC). In a previous study on HNSCC cell lines, we found that epigalocathechin-3-gallate (EGCG), a major biologically active component of green tea, inhibited activation of the epidermal growth factor receptor (EGFR) and thereby inhibited EGFR-related downstream signaling pathways in HNSCC cells. In the present study, we examined the effects of EGCG on activation of the HER-2 receptor in human HNSCC and breast carcinoma cell lines that display constitutive activation of HER-2. Treatment of these cells with 10 or 30 microg of EGCG, respectively, doses that cause 50% inhibition of growth, markedly inhibited the phosphorylation of HER-2 in both cell lines. This was associated with inhibition of Stat3 activation, inhibition of c-fos and cyclin D1 promoter activity, and decreased cellular levels of the cyclin D1 and Bcl-XL proteins. Although these concentrations of EGCG are quite high, we found that concentrations of 0.1-1.0 microg/ml, which are in the range of plasma concentrations after administering a single oral dose of EGCG or a green tea extract, markedly enhanced the sensitivity of both types of cell lines to growth inhibition by Taxol, a drug frequently used in the treatment of breast carcinoma and HNSCC. These results, taken together with previous evidence that EGCG also inhibits activation of the EGFR in carcinoma cells, suggest that EGCG may be useful in treating cases of breast carcinoma and HNSCC in which activation of the EGFR and/or HER-2 plays important roles in tumor survival and growth.
Masuda
Muneyuki
M
Herbert Irving Comprehensive Cancer Center, Columbia University, College of Physicians and Surgeons, New York, New York 10032, USA.
Suzui
Masumi
M
Lim
Jin T E
JT
Weinstein
I Bernard
IB
D000972:Antineoplastic Agents, Phytogenic / Q000494:pharmacology; D015153:Blotting, Western; D001943:Breast Neoplasms / Q000188:drug therapy*; D002277:Carcinoma / Q000188:drug therapy*; D002392:Catechin / Q000031:analogs & derivatives* / Q000494:pharmacology*; D002455:Cell Division; D045744:Cell Line, Tumor; D019938:Cyclin D1 / Q000096:biosynthesis; D004305:Dose-Response Relationship, Drug; D004797:Enzyme-Linked Immunosorbent Assay; D015972:Gene Expression Regulation, Neoplastic; D017930:Genes, Reporter; D006258:Head and Neck Neoplasms / Q000188:drug therapy*; D006801:Humans; D015151:Immunoblotting; D008156:Luciferases / Q000378:metabolism; D017239:Paclitaxel / Q000494:pharmacology; D010766:Phosphorylation; D011379:Prognosis; D011401:Promoter Regions, Genetic; D016760:Proto-Oncogene Proteins c-fos / Q000096:biosynthesis; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000378:metabolism*; D015398:Signal Transduction; D013997:Time Factors
D000972:Antineoplastic Agents, Phytogenic; D002392:Catechin; D019938:Cyclin D1; D008156:Luciferases; D017239:Paclitaxel; D016760:Proto-Oncogene Proteins c-fos; D018719:Erb-b2 Receptor Tyrosine Kinases; C045651:epigallocatechin gallate