title: Inhibition of platelet-derived growth factor receptor tyrosine kinase and downstream signaling pathways by Compound C.
abstract: AMP-activated protein kinase (AMPK) has been implicated in anti-proliferative actions in a range of cell systems. Recently, it was observed that Compound C, an inhibitor of AMPK, also reduced the cell viability in human diploid fibroblasts (HDFs). Compound C-induced growth arrest was associated with a decrease in the cell cycle regulatory proteins, such as proliferating cell nuclear antigen, phosphorylated pRB, cyclin-dependent protein kinases (Cdk 2 and 4), cyclins (D and E), and the Cdk inhibitors (p21, p16, and p27). Therefore, the present study examined the molecular mechanism of the antiproliferative effects of Compound C. Although Compound C inhibited serum-induced phosphorylation of Akt and its substrate, glycogen synthase kinase-3β, it did not affect the Akt activity in vitro. Compound C significantly inhibited the receptor tyrosine phosphorylation and the activity of downstream signaling molecules, such as p85 phosphoinositide 3-kinase, phospholipase C-γ1, and extracellular signal-regulated kinase 1/2, induced by platelet-derived growth factor (PDGF) but not by epidermal growth factor- and insulin-like growth factor. In vitro growth factor receptor tyrosine kinase activity profiling revealed the IC50 for PDGF receptor-β (PDGFRβ) to be 5.07μM, whereas the IC50 for the epidermal growth factor receptor and insulin-like growth factor receptor was ≥100μM. The inhibitory effect of Compound C on PDGFRβ and Akt was also observed in AMPKα1/α2-knockout mouse embryonic fibroblasts, indicating that its inhibitory effect is independent of the AMPK activity. The inhibitory effect of Compound C on cell proliferation and PDGFRβ tyrosine phosphorylation was also demonstrated in various PDGFR-expressing cells, including MRC-5, BEAS-2B, rat aortic vascular smooth muscle cells, and A172 glioblastoma cells. These results indicate that Compound C can be used as a potential antiproliferative agent for PDGF- or PDGFR-associated diseases, such as cancer, atherosclerosis, and fibrosis.
authors.affiliation: Department of Biochemistry, Gachon University School of Medicine, Incheon 406-799, Korea.
authors.forename: Hyun Jin
authors.initials: HJ
authors.lastname: Kwon
authors.forename: Go-Eun
authors.initials: GE
authors.lastname: Kim
authors.forename: Yun Taek
authors.initials: YT
authors.lastname: Lee
authors.forename: Meong-Sook
authors.initials: MS
authors.lastname: Jeong
authors.forename: Insug
authors.initials: I
authors.lastname: Kang
authors.forename: Dongki
authors.initials: D
authors.lastname: Yang
authors.forename: Eui-Ju
authors.initials: EJ
authors.lastname: Yeo
mesh_terms: D055372:AMP-Activated Protein Kinases / Q000235:genetics / Q000378:metabolism; D000818:Animals; D002460:Cell Line; D058543:Class Ia Phosphatidylinositol 3-Kinase / Q000378:metabolism; D066246:ErbB Receptors / Q000378:metabolism; D059585:G1 Phase Cell Cycle Checkpoints / Q000187:drug effects; D038362:Glycogen Synthase Kinase 3 / Q000378:metabolism; D000071679:Glycogen Synthase Kinase 3 beta; D006801:Humans; D051379:Mice; D018345:Mice, Knockout; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism; D051966:Phospholipase C gamma / Q000378:metabolism; D010766:Phosphorylation; D010982:Platelet-Derived Growth Factor / Q000494:pharmacology; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D011720:Pyrazoles / Q000494:pharmacology*; D011743:Pyrimidines / Q000494:pharmacology*; D051381:Rats; D017526:Receptor, IGF Type 1 / Q000378:metabolism; D017479:Receptors, Platelet-Derived Growth Factor / Q000037:antagonists & inhibitors* / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects*
chemical_list: D010982:Platelet-Derived Growth Factor; D011720:Pyrazoles; D011743:Pyrimidines; C516138:dorsomorphin; D058543:Class Ia Phosphatidylinositol 3-Kinase; D066246:ErbB Receptors; C099852:PDGF receptor tyrosine kinase; D017526:Receptor, IGF Type 1; D017479:Receptors, Platelet-Derived Growth Factor; C548179:Prkaa1 protein, mouse; C534978:Prkaa2 protein, mouse; C000605506:GSK3B protein, human; D000071679:Glycogen Synthase Kinase 3 beta; C000605507:Gsk3b protein, mouse; C000605508:Gsk3b protein, rat; D051057:Proto-Oncogene Proteins c-akt; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D038362:Glycogen Synthase Kinase 3; D055372:AMP-Activated Protein Kinases; D051966:Phospholipase C gamma