Ochnaflavone inhibits TNF-alpha-induced human VSMC proliferation via regulation of cell cycle, ERK1/2, and MMP-9.
Ochnaflavone (c-3 of apigenin-0-c-4 of apigenin; OC), a biflavonoid present in the human diet, is known to inhibit angiotensin II-induced hypertrophy and serum-induced smooth muscle cell proliferation. OC is known to have anti-fungal and anti-inflammatory activities. However, it is not known whether OC exerts similar cardioprotective effects in cells treated with tumor necrosis factor (TNF)-alpha. In this study, we isolated OC from Lonicera japonica and studied its effect on matrix metalloproteinase-9 (MMP-9) gene expression in human aortic smooth muscle cells (HASMC). Furthermore, we investigated whether OC exerts the multiple suppressive effects on cytokine TNF-alpha-induced HASMC. Treatment of OC showed its potent inhibitory effects on DNA synthesis of cultured HASMC in the presence of TNF-alpha. These inhibitory effects were associated with reduced extracellular signal-regulated kinase 1/2 (ERK1/2) activity and G1 cell cycle arrest. Treatment of OC, which induced a cell cycle block in G1-phase, induced downregulation of cyclins and CDKs and upregulation of the CDK inhibitor p21(waf1) expression, whereas upregulation of p27 or p53 by OC was not observed. Because anti-atherogenic effects need not be limited to anti-proliferation, we decided to examine whether OC exerts inhibitory effects on MMP-9 activity in TNF-alpha-induced HASMC. OC inhibited TNF-alpha-induced MMP-9 secretion on HASMC in a dose-dependent manner. This inhibition was characterized by downregulation of MMP-9, which was transcriptionally regulated at nuclear factor (NF)-kappaB site and activation protein (AP)-1 site in the MMP-9 promoter. These findings indicate the efficacy of OC in inhibiting cell proliferation, G1 to S-phase cell cycle progress, and MMP-9 expression through the transcription factors NF-kappaB and AP-1 on TNF-alpha-induced HASMC. The findings of the present study may provide a potential mechanism that explains the anti-atherogenic activity of OC.
Suh
Seok-Jong
SJ
Department of Biological Sciences, SungKyunKwan University and NRL-Glycobiology, 300 Chunchun-Dong, Jangan-Gu, Suwon City, Kyunggi-Do 440-746, Korea.
Jin
Un-Ho
UH
Kim
Sung-Hoon
SH
Chang
Hyeun-Wook
HW
Son
Jong-Keun
JK
Lee
Seung Ho
SH
Son
Kun-Ho
KH
Kim
Cheorl-Ho
CH
D002453:Cell Cycle / Q000502:physiology; D049109:Cell Proliferation; D002478:Cells, Cultured; D050759:Cyclin-Dependent Kinase Inhibitor p21 / Q000378:metabolism; D004790:Enzyme Induction; D005419:Flavonoids / Q000737:chemistry / Q000494:pharmacology*; D006801:Humans; D020780:Matrix Metalloproteinase 9 / Q000235:genetics / Q000378:metabolism*; D019950:Mitogen-Activated Protein Kinase 1 / Q000235:genetics / Q000378:metabolism*; D048052:Mitogen-Activated Protein Kinase 3 / Q000235:genetics / Q000378:metabolism*; D015394:Molecular Structure; D009131:Muscle, Smooth, Vascular / Q000166:cytology; D032389:Myocytes, Smooth Muscle / Q000166:cytology / Q000502:physiology*; D016328:NF-kappa B / Q000235:genetics / Q000378:metabolism; D011401:Promoter Regions, Genetic; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism*
D050759:Cyclin-Dependent Kinase Inhibitor p21; D005419:Flavonoids; D016328:NF-kappa B; D014409:Tumor Necrosis Factor-alpha; C090940:ochnaflavone; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020780:Matrix Metalloproteinase 9