title: Epigallocatechin-3-gallate (EGCG) inhibits PC-3 prostate cancer cell proliferation via MEK-independent ERK1/2 activation.
abstract: Epigallocatechin-3-gallate (EGCG), a tea polyphenol, inhibits the proliferation of many cancer cell lines; however, the antiproliferative mechanism(s) are not well-characterized. The objective of this study is to identify the cellular signaling mechanism(s) responsible for the antiproliferative effects of EGCG in the PC-3 prostate cancer cell line. EGCG inhibited PC-3 cell proliferation in a concentration-dependent manner with an IC(50) value of 39.0 microM, but had no effect on the proliferation of a nontumorigenic prostate epithelial cell line (RWPE-1). Treatment of PC-3 cells with EGCG (0-50 microM) resulted in time and concentration-dependent activation of the extracellular signal-regulated kinase (ERK1/2) pathway. EGCG treatment did not induce ERK1/2 activity in RWPE-1 cells. The activation of ERK1/2 by EGCG was not inhibited using PD98059, a potent inhibitor of mitogen-activated protein kinase kinase (MEK), the immediate upstream kinase responsible for ERK1/2 activation; suggesting a MEK-independent signaling mechanism. Pretreatment of PC-3 cells with a phosphoinositide-3 kinase (PI3K) inhibitor partially reduced both EGCG-induced ERK1/2 activation and the antiproliferative effects of this polyphenol. These results suggest that ERK1/2 activation via a MEK-independent, PI3-K-dependent signaling pathway is partially responsible for the antiproliferative effects of EGCG in PC-3 cells.
authors.affiliation: Department of Human Nutrition, The Ohio State University, 1787 Neil Avenue, 325 Campbell Hall, Columbus, OH 43210, United States.
authors.forename: Daniel S
authors.initials: DS
authors.lastname: Albrecht
authors.forename: Elizabeth A
authors.initials: EA
authors.lastname: Clubbs
authors.forename: Mario
authors.initials: M
authors.lastname: Ferruzzi
authors.forename: Joshua A
authors.initials: JA
authors.lastname: Bomser
mesh_terms: D016588:Anticarcinogenic Agents / Q000494:pharmacology; D002392:Catechin / Q000031:analogs & derivatives* / Q000494:pharmacology; D002460:Cell Line; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects*; D002867:Chromones / Q000494:pharmacology; D004789:Enzyme Activation / Q000187:drug effects; D004847:Epithelial Cells / Q000187:drug effects / Q000378:metabolism; D005419:Flavonoids / Q000494:pharmacology; D006801:Humans; D020128:Inhibitory Concentration 50; D008297:Male; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism*; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism*; D020929:Mitogen-Activated Protein Kinase Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D009025:Morpholines / Q000494:pharmacology; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D000081082:Phosphoinositide-3 Kinase Inhibitors; D010766:Phosphorylation / Q000187:drug effects; D011471:Prostatic Neoplasms / Q000378:metabolism / Q000473:pathology; D047428:Protein Kinase Inhibitors / Q000494:pharmacology
chemical_list: D016588:Anticarcinogenic Agents; D002392:Catechin; D002867:Chromones; D005419:Flavonoids; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020929:Mitogen-Activated Protein Kinase Kinases; D009025:Morpholines; D019869:Phosphatidylinositol 3-Kinases; D000081082:Phosphoinositide-3 Kinase Inhibitors; D047428:Protein Kinase Inhibitors; C085911:2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one; C045651:epigallocatechin gallate; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one