title: Signal transduction pathway for L-ascorbic acid- and L-ascorbic acid 2-glucoside-induced DNA synthesis and cell proliferation in primary cultures of adult rat hepatocytes.
abstract: We examined the effects of L-ascorbic acid and its analogues on DNA synthesis and cell proliferation. We also investigated the signal transduction pathways involved in the induction of mitogenesis by L-ascorbic acid and its analogues using primary cultures of adult rat hepatocytes. Following a 4-h serum-free cultivation, both L-ascorbic acid and its stable analogue, L-ascorbic acid 2-glucoside, time- and dose-dependently stimulated hepatocyte DNA synthesis and cell proliferation, with EC₅₀ values of 6.46×10⁻⁸ M and 3.34×10⁻⁸ M, respectively. Dehydroascorbic acid (10⁻⁶ M-10⁻⁵ M) weakly stimulated hepatocyte mitogenesis, whereas isoascorbic acid (10⁻⁹ M-10⁻⁵ M) had no effect. Hepatocyte mitogenesis induced by L-ascorbic acid or L-ascorbic acid 2-glucoside was dose-dependently abolished by treatment with monoclonal antibodies against insulin-like growth factor (IGF)-I receptor, but not by treatment with monoclonal antibodies against insulin receptor or IGF-II receptor. Western blot analysis showed that both L-ascorbic acid and L-ascorbic acid 2-glucoside significantly stimulated IFG-I receptor tyrosine kinase activity within 3 min, and mitogen-activated protein (MAP) kinase activity within 5 min. These results demonstrate that both L-ascorbic acid and L-ascorbic acid 2-glucoside induce DNA synthesis and cell proliferation in primary cultures of adult rat hepatocytes by interacting with the IGF-I receptor site and by activating the receptor tyrosine kinase/MAP kinase pathway.
authors.affiliation: Department of Clinical Pharmacology, Faculty of Pharmaceutical Sciences, Josai University, 1-1 Keyakidai, Sakado City, Saitama 350-0295, Japan.
authors.forename: Hajime
authors.initials: H
authors.lastname: Moteki
authors.forename: Yuya
authors.initials: Y
authors.lastname: Shimamura
authors.forename: Mitsutoshi
authors.initials: M
authors.lastname: Kimura
authors.forename: Masahiko
authors.initials: M
authors.lastname: Ogihara
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000494:pharmacology; D057134:Antibodies, Neutralizing / Q000494:pharmacology; D001205:Ascorbic Acid / Q000031:analogs & derivatives* / Q000378:metabolism* / Q000494:pharmacology; D049109:Cell Proliferation / Q000187:drug effects; D002478:Cells, Cultured; D004247:DNA / Q000096:biosynthesis*; D005960:Glucosides / Q000494:pharmacology; D022781:Hepatocytes / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D020935:MAP Kinase Signaling System / Q000187:drug effects; D008297:Male; D008934:Mitogens / Q000494:pharmacology*; D009994:Osmolar Concentration; D051381:Rats; D017208:Rats, Wistar; D017526:Receptor, IGF Type 1 / Q000037:antagonists & inhibitors / Q000378:metabolism; D017527:Receptor, IGF Type 2 / Q000037:antagonists & inhibitors / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D013997:Time Factors
chemical_list: D000911:Antibodies, Monoclonal; D057134:Antibodies, Neutralizing; D005960:Glucosides; D008934:Mitogens; D017527:Receptor, IGF Type 2; C065378:ascorbic acid 2-O-glucoside; D004247:DNA; D017526:Receptor, IGF Type 1; D001205:Ascorbic Acid