Ochnaflavone inhibits TNF‐α‐induced human VSMC proliferation via regulation of cell cycle, ERK1/2, and MMP‐9

Abstract

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.

Rhein Inhibits TNF-α-Induced Human Aortic Smooth Muscle Cell Proliferation via Mitochondrial-Dependent Apoptosis

“…Previous reports have shown that rhein induces apoptosis in promyelocytic leukemia HL-60 cells [24], and it is well known TNF-α-induced HASMC proliferation plays a critical role in development of vascular diseases including atherosclerosis [2,5,6,7,8,9]. However, the effect of rhein on TNF-α-induced HASMC proliferation is not well understood.…”

“…Inflammatory cytokines such as TNF-α are secreted by VSMCs in the neointima after a balloon injury, as well as by macrophages in atherosclerotic lesions [33]. In addition, inflammatory cytokines also play an important role in the induction of inflammation, migration and proliferation in HASMCs [3,4,5,6,7,8]. …”

“…Especially, TNF-α is secreted by VSMCs in the neointima after a balloon injury as well as by macrophages in atherosclerotic lesions [3, 4]. Previous studies have shown that TNF-α induces an increase in DNA synthesis as well as the proliferation of VSMCs [5,6,7,8,9]. …”

Ochnaflavone, a Natural Biflavonoid, Induces Cell Cycle Arrest and Apoptosis in HCT-15 Human Colon Cancer Cells

“…Various compounds derived from natural products have been reported to modulate the growth of colorectal cancer cells and thus are considered to be cancer chemopreventive agents (Bhanot and Möller, 2009). Ochnaflavone is a natural biflavonoid and has been demonstrated to have anti-inflammatory and anti-arthreogenic activites (Lee et al, 1997;Moon et al, 2006;Son et al, 2006;Suh et al, 2006a;Suh et al, 2006b;Kim et al, 2008). Since chronic inflammation is highly correlated with colorectal carcinogenesis (Wada, 2009;Bhanot and Möller, 2009), anti-inflammatory effect of ochnaflavone might suggest its possible role in colon cancer chemoprevention.…”

“…Several biological activities mediated by ochnaflavone include the inhibition of phospholipase A2 in rat platelet, lymphocyte proliferation, and arachidonate release from rat peritoneal macrophage (Chang et al, 1994;Lee et al, 1995;Lee et al, 1997). The anti-artherogenic activity of ochnaflavone was also revealed with the correlation of inhibition of human vascular smooth muscle cell proliferation induced by TNF-α via regulation of cell cycle related proteins, ERK and MMP-9 (Suh et al, 2006b). Recent study also exhibited the inhibitory activity of CCl4-induced PE degradation in rat liver microsome and anti-inflammatory effects with the downregulation of inducible nitric oxide, cyclooxygenase-2 and 5-lipoxygenase through NF-κB and ERK pathway by ochnaflavone Suh et al, 2006a).…”