title: 3-OH flavone inhibition of epidermal growth factor-induced proliferaton through blocking prostaglandin E2 production.
abstract: Epidermal growth factor (EGF) has been shown to induce proliferation in cells, however, the role of prostaglandin E(2) (PGE(2)) plays in EGF-induced proliferation in still unclear. EGF and PGE(2) showed proliferation responses in epidermoid carcinoma cell A431 by MTT and [(3)H] thymidine incorporation assay. Activation of the EGF receptor and extracellular signal-regulated protein kinases (ERK1/2), but not p38 and JNK, appeared 10 min after EGF treatment, whereas total amounts of ERK1/2, p38 and JNK remained unchanged in A431 cells, accompanied by induction of COX-2 and PGE(2) production. PD98059, a specific ERK1/2 inhibitor, inhibited EGF-induced proliferation with concomitant decreases in ERK1/2 phosphorylation and COX-2/PGE(2) induction. Non-steroid anti-inflammatory drugs (NSAIDs) such as aspirin and diclofenac, a COX activity inhibitor, inhibited EGF-induced proliferation by blocking PGE(2) production. The addition of PGE(2) reversed the inhibitory effects of PD98059, aspirin, and diclofenac on EGF-induced proliferation. This suggests that COX-2/PGE(2) activation involves in EGF-induced proliferation and locates at the downstream of ERK1/2 activation. Furthermore, the natural product, 3-OH flavone, showed the most-potent inhibitory activity on EGF-induced proliferation among 9 structurally-related compounds, and suppression of EGF receptor phosphorylation, ERK1/2 phosphorylation, and COX-2/PGE(2) production by 3-OH flavone was identified. PGE(2) addition attenuates the inhibitory activity of 3-OH flavone on EGF-induced proliferation by MTT assay and colony formation by soft agar assay. Additionally, 3-OH flavone also showed more-specific inhibition on EGF- than on fetal bovine serum (FBS)-induced proliferation in A431 cells. Results of our present study provide evidence to demonstrate that PGE(2) is an important downstream molecule in EGF-induced proliferation, and 3-OH flavone, which inhibits PGE(2) production by blocking MAPK cascade, might reserve potential for development as an anti-cancer drug.
authors.affiliation: Department of Dermatology, School of Medicine, Taipei Medical University, Taipei, Taiwan, Republic of China.
authors.forename: Shing-Chuan
authors.initials: SC
authors.lastname: Shen
authors.forename: Ching-Huai
authors.initials: CH
authors.lastname: Ko
authors.forename: Kuo-Chou
authors.initials: KC
authors.lastname: Hsu
authors.forename: Yen-Chou
authors.initials: YC
authors.lastname: Chen
mesh_terms: D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000494:pharmacology; D002294:Carcinoma, Squamous Cell / Q000201:enzymology / Q000473:pathology*; D002455:Cell Division / Q000187:drug effects; D003114:Colony-Forming Units Assay; D051546:Cyclooxygenase 2; D052246:Cyclooxygenase 2 Inhibitors; D016861:Cyclooxygenase Inhibitors / Q000494:pharmacology; D015232:Dinoprostone / Q000037:antagonists & inhibitors / Q000378:metabolism*; D004789:Enzyme Activation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004815:Epidermal Growth Factor / Q000037:antagonists & inhibitors* / Q000494:pharmacology; D066246:ErbB Receptors / Q000378:metabolism; D005419:Flavonoids / Q000494:pharmacology*; D015971:Gene Expression Regulation, Enzymologic; D006801:Humans; D007527:Isoenzymes / Q000037:antagonists & inhibitors / Q000378:metabolism; D048031:JNK Mitogen-Activated Protein Kinases; D048670:MAP Kinase Kinase 4; D008565:Membrane Proteins; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3; D020929:Mitogen-Activated Protein Kinase Kinases / Q000378:metabolism; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D011451:Prostaglandin-Endoperoxide Synthases / Q000378:metabolism; D013778:Tetrazolium Salts; D013844:Thiazoles; D014407:Tumor Cells, Cultured; D048051:p38 Mitogen-Activated Protein Kinases
chemical_list: D000894:Anti-Inflammatory Agents, Non-Steroidal; D052246:Cyclooxygenase 2 Inhibitors; D016861:Cyclooxygenase Inhibitors; D004791:Enzyme Inhibitors; D005419:Flavonoids; D007527:Isoenzymes; D008565:Membrane Proteins; D013778:Tetrazolium Salts; D013844:Thiazoles; D004815:Epidermal Growth Factor; D051546:Cyclooxygenase 2; C496540:PTGS2 protein, human; D011451:Prostaglandin-Endoperoxide Synthases; D066246:ErbB Receptors; D048031:JNK Mitogen-Activated Protein Kinases; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases; D048670:MAP Kinase Kinase 4; D020929:Mitogen-Activated Protein Kinase Kinases; C022616:thiazolyl blue; D015232:Dinoprostone; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one; C041477:3-hydroxyflavone