title: Reversal of the TPA-induced inhibition of gap junctional intercellular communication by Chaga mushroom (Inonotus obliquus) extracts: effects on MAP kinases.
abstract: Chaga mushroom (Inonotus obliquus) has continued to receive attention as a folk medicine with indications for the treatment of cancers and digestive diseases. The anticarcinogenic effect of Chaga mushroom extract was investigated using a model system of gap junctional intercellular communication (GJIC) in WB-F344 normal rat liver epithelial cells. The cells were pre-incubated with Chaga mushroom extracts (5, 10, 20 microg/ml) for 24 h and this was followed by co-treatment with Chaga mushroom extracts and TPA (12-O-tetradecanoylphorbol-13-acetate, 10 ng/ml) for 1 h. The inhibition of GJIC by TPA (12-O-tetradecanoylphorbol-13-acetate), promoter of cancer, was prevented with treatment of Chaga mushroom extracts. Similarly, the increased phosphorylated ERK1/2 and p38 protein kinases were markedly reduced in Chaga mushroom extracts-treated cells. There was no change in the JNK kinase protein level, suggesting that Chaga mushroom extracts could only block the activation of ERK1/2 and p38 MAP kinase. The Chaga mushroom extracts further prevented the inhibition of GJIC through the blocking of Cx43 phosphorylation. Indeed cell-to-cell communication through gap junctional channels is a critical factor in the life and death balance of cells because GJIC has an important function in maintaining tissue homeostasis through the regulation of cell growth, differentiation, apoptosis and adaptive functions of differentiated cells. Thus Chaga mushroom may act as a natural anticancer product by preventing the inhibition of GJIC through the inactivation of ERK1/2 and p38 MAP kinase.
authors.affiliation: Laboratory of Stem Cell and Tumor Biology, Department of Veterinary Public Health, College of Veterinary Medicine and BK 21 Program for Veterinary Science, Seoul National University, Sillim 9-dong, Gwanak-gu, Seoul 151-742, South Korea.
authors.forename: Jung-Ran
authors.initials: JR
authors.lastname: Park
authors.forename: Joon-Suk
authors.initials: JS
authors.lastname: Park
authors.forename: Eun-Hye
authors.initials: EH
authors.lastname: Jo
authors.forename: Jae-Woong
authors.initials: JW
authors.lastname: Hwang
authors.forename: Sun-Jung
authors.initials: SJ
authors.lastname: Kim
authors.forename: Jeong-Chan
authors.initials: JC
authors.lastname: Ra
authors.forename: Okezie I
authors.initials: OI
authors.lastname: Aruoma
authors.forename: Yong-Soon
authors.initials: YS
authors.lastname: Lee
authors.forename: Kyung-Sun
authors.initials: KS
authors.lastname: Kang
mesh_terms: D000363:Agaricales / Q000737:chemistry*; D000818:Animals; D016588:Anticarcinogenic Agents / Q000737:chemistry / Q000494:pharmacology*; D015153:Blotting, Western; D002450:Cell Communication / Q000187:drug effects*; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D018031:Connexin 43 / Q000378:metabolism; D004847:Epithelial Cells / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D017629:Gap Junctions / Q000187:drug effects / Q000378:metabolism / Q000502:physiology; D048670:MAP Kinase Kinase 4 / Q000378:metabolism; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D010766:Phosphorylation / Q000187:drug effects; D051381:Rats; D013755:Tetradecanoylphorbol Acetate / Q000037:antagonists & inhibitors* / Q000494:pharmacology; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism
chemical_list: D016588:Anticarcinogenic Agents; D018031:Connexin 43; D019950:Mitogen-Activated Protein Kinase 1; D020928:Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases; D048670:MAP Kinase Kinase 4; D013755:Tetradecanoylphorbol Acetate