title: 20-HETE inhibits the proliferation of vascular smooth muscle cells via transforming growth factor-beta.
abstract: 20-Hydroxyeicosatetraenoic acid (20-HETE), a cytochrome P450 arachidonic acid metabolite, has been shown to modulate the growth of vascular smooth muscle cells (VSMCs). We asked whether 20-HETE modulates the proliferation of R22D cells, a clonal VSMC from neonatal rats, by releasing transforming growth factor-beta (TGF-beta). Incubation of R22D cells with 20-HETE for 24 h attenuated [(3)H]thymidine incorporation in a concentration-dependent manner without causing the release of lactate dehydrogenase. 20-HETE also inhibited platelet-derived growth factor (PDGF)-induced [(3)H]thymidine incorporation in R22D cells and human VSMCs. At 5 muM, 20-HETE reduced [(3)H]thymidine incorporation by 34 +/- 6%; anti-TGF-beta neutralizing antibody, but not nonspecific IgG, completely reversed the attenuated [(3)H]thymidine incorporation induced by 20-HETE. In addition, 20-HETE attenuated fetal bovine serum- and PDGF-induced expression of cyclin D1, a downstream effector of TGF-beta(1), which was reversed by anti-TGF-beta antibody. Further studies demonstrated that 20-HETE may increase TGF-beta release to a level high enough to inhibit [(3)H]thymidine incorporation without altering the steady-state mRNA level of TGF-beta. Nevertheless, pretreatment of indomethacin (a cyclooxygenase inhibitor) or paxilline (a potassium channel inhibitor) did not affect the inhibitory effect on DNA synthesis induced by 20-HETE. These results demonstrate for the first time a growth-inhibitory effect induced by 20-HETE, which may be mediated by TGF-beta.
authors.affiliation: Department of Physiology and Pharmacology, Center for Healthy Aging Research, Chang Gung University, Kuei-Shan, Tao-Yuan, Taiwan ROC.
authors.forename: Chan-Jung
authors.initials: CJ
authors.lastname: Liang
authors.forename: Harlan E
authors.initials: HE
authors.lastname: Ives
authors.forename: Chuen-Mao
authors.initials: CM
authors.lastname: Yang
authors.forename: Yunn-Hwa
authors.initials: YH
authors.lastname: Ma
mesh_terms: D000818:Animals; D049109:Cell Proliferation; D002478:Cells, Cultured; D019938:Cyclin D1 / Q000378:metabolism; D004247:DNA / Q000096:biosynthesis; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D006801:Humans; D006893:Hydroxyeicosatetraenoic Acids / Q000494:pharmacology*; D020929:Mitogen-Activated Protein Kinase Kinases / Q000378:metabolism; D009131:Muscle, Smooth, Vascular / Q000166:cytology* / Q000378:metabolism*; D010982:Platelet-Derived Growth Factor / Q000378:metabolism; D051381:Rats; D016212:Transforming Growth Factor beta / Q000378:metabolism*
chemical_list: D006893:Hydroxyeicosatetraenoic Acids; D010982:Platelet-Derived Growth Factor; D016212:Transforming Growth Factor beta; D019938:Cyclin D1; C055987:20-hydroxy-5,8,11,14-eicosatetraenoic acid; D004247:DNA; D048049:Extracellular Signal-Regulated MAP Kinases; D020929:Mitogen-Activated Protein Kinase Kinases