Enhancing Effects of Scutellaria baicalensis and Some of its Constituents on TGF-β1 Gene Expression in RAW 264.7 Murine Macrophage Cell Line

Abstract

Transforming growth factor β1 (TGF-β1) has been implicated as an inhibitor of cell proliferation and a potent inducer of apoptosis. Scutellaria baicalensis Georgi (SbG) has been widely used in Asia and recent investigations have shown that SbG has anticancer, antiviral, and anti-inflammatory effects. The aim of this study is to investigate the modulatory effect of SbG on TGF-β1 gene expression. By using RAW 264.7 cell line as an in vitro model, the effects of SbG on TGF-β1 gene expression were evaluated by ELISA, reverse-transcription polymerase chain reaction (RT-PCR) and quantitative PCR. Many inhibitors such as mitogen-activated protein kinase (MAPK) inhibitor (PD98059), p38-MAPK inhibitor (SB203580), NF-κB inhibitor (aspirin) and protein kinase C inhibitor (H7) were used to determine the possible signal transduction pathways. The results showed that crude extracts of SbG as well as its pure compounds, baicalin, baicalein and chrysin up-regulated TGF-β1 gene expression on RAW 264.7 cells in a concentration-dependent manner. However, the flavonoid of SbG, wogonin, did not up-regulate TGF-β1 expression on gene and protein levels on RAW264.7 cells. The facts that aspirin and H7 but not PD98059 and SB203580 blocked the enhancing effect suggested that NF-κB and PKC might be involved in baicalin-enhanced TGF-β1 gene expression. We conclude that SbG up-regulates TGF-β1 gene expression on RAW264.7 cells through NF-κB and PKC pathways and this might provide evidence to explain the therapeutic effect and potential adverse effects on the clinical use of Scutellaria baicalensis Georgi.

Key words

Scutellaria baicalensis Georgi - Lamiaceae - TGF-β1 - macrophages - alternative medicine

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