Selective fraction of Scutellaria baicalensis and its chemopreventive effects on MCF-7 human breast cancer cells

Scutellaria extract and wogonin inhibit tumor-mediated induction of T(reg) cells via inhibition of TGF-β1 activity

A number of studies have implicated tumor-induced T(reg) cell activity in the sub-optimal response to therapeutic vaccines. Development of neo-adjuvant strategies targeting T(reg) cells is therefore imperative. Scutellaria extracts or constituent flavonoids have shown encouraging efficacy against various tumors, including gliomas, in both pre-clinical and clinical studies. We report here, for the first time, that Scutellaria ocmulgee leaf extract (SocL) and flavonoid wogonin could inhibit TGF-β1-induced T(reg) activity in malignant gliomas. F344 rats, subcutaneously transplanted with F98 gliomas, were treated with SocL. There was a significant inhibition of intra-tumoral TGF-β1 and T(reg) cell frequency as well as peripheral blood TGF-β1 levels in SocL-treated animals compared to the controls. SocL extract and wogonin also inhibited glioma-induced, TGF-β1-mediated T(reg) activity in vitro. SocL extract and wogonin also inhibited the secretion of IL-10 in T(reg) culture; whereas the level of IL-2 was either unchanged or marginally enhanced. We also observed an inhibition of Smad-3, GSK-3β and ERK1/2 signaling by SocL and wogonin in T(reg) cells, while phosphorylation of P38 MAPK was considerably enhanced, indicating that SocL or wogonin could inhibit the T cells' response to TGF-β1 via modulation of both Smad and non-Smad signaling pathways. Overall, this study suggests that Scutellaria can potentially reverse tumor-mediated immune suppression via inhibition of TGF-β1 secretion as well as via inhibition of T cells' response to TGF-β1. This may provide an opportunity for developing a novel adjuvant therapeutic strategy for malignant gliomas, combining Scutellaria with immunotherapy and chemo/radio-therapeutic regimen, which could potentially improve the disease outcome.

Apigenin inhibits hepatoma cell growth through alteration of gene expression patterns

Apigenin, a common plant flavonoid, has been shown to possess anti-tumor properties; however, the underlying molecular mechanisms are still not completely understood. In the present study, we investigated the effects of apigenin on human hepatoma Huh7 cell proliferation, cell cycle distribution, apoptosis, and colony formation in vitro, as well as on the tumorigenicity of Huh7 cells in vivo. To get more insight into the mechanism of apigenin action, we performed genome-wide expression profiling of apigenin-treated Huh7 cells using cDNA microarrays (Agilent Whole Human Genome Oligo Microarray) that contain 41,000 genes. Ten of the most differentially expressed genes (≧5-fold changes) were selected for further evaluation by quantitative RT-PCR (qPCR) and Western blot analyses. Notably, apigenin (5-20 μg/ml) remarkably inhibited Huh7 cell proliferation and colony formation as compared to the vehicle control, which was in a dose-dependent manner. Accompanying with the decreased growth, apigenin-treated cells showed a cell cycle arrest at G2/M phase and an increased rate of apoptosis. Moreover, the xenografts derived from Huh7 cells were significantly (p<0.05) retarded by the delivery of apigenin (50 μg/mouse/day) relative to the control counterparts. Gene expression profile analysis revealed that 1336 genes were up-regulated and 428 genes were down-regulated by apigenin. The down-regulation of interleukin-4 receptor and ubiquitin specific protease 18 and the up-regulation of SLC27A3 and chemokine (C-C motif) receptor 2 were further confirmed by the qPCR and Western blot results. In conclusion, apigenin exhibits inhibitory effects on hepatoma cell growth, which is likely mediated through alteration of gene expression profiles.

Analyzing Cytotoxic and Apoptogenic Properties of Scutellaria litwinowii Root Extract on Cancer Cell Lines

The Scutellaria species (Lamiaceae) is used as a source of flavonoids to treat a variety of diseases in traditional medicine. In spite of many reports about the cytotoxic and antitumor effects of some species of this genus, anticancer researches on one of the Iranian species S. litwinowii have not yet been conducted. The cytotoxic properties of total methanol extract of S. litwinowii and its fractions were investigated on different cancer cell lines including AGS, HeLa, MCF-7, PC12 and NIH 3T3. Meanwhile, the role of apoptosis in this toxicity was explored. The cells were cultured in DMEM medium and incubated with different concentrations of herb plant extracts. Cell viability was quantitated by MTT assay. Apoptotic cells were determined using propidium iodide staining of DNA fragmentation by flow cytometry (sub-G1 peak). Scutellaria litwinowii inhibited the growth of malignant cells in a dose-dependent manner. Among solvent fractions of S. litwinowii, the methylene chloride fraction was found to be more toxic compared to other fractions. The IC₅₀ values of this fraction against AGS, HeLa, MCF-7 and PC12 cell lines after 24 h were determined, 121.2 ± 3.1, 40.9 ± 2.5, 115.9 ± 3.5 and 64.5 ± 3.4 μg/ml, respectively. Scutellaria litwinowii induced a sub-G1 peak in the flow cytometry histogram of treated cells compared to control cells indicating that apoptotic cell death is involved in S. litwinowii toxicity. Scutellaria litwinowii exerts cytotoxic and proapototic effects in a variety of malignant cell lines and could be considered as a potential chemotherapeutic agent in cancer treatment.

Korean Scutellaria baicalensis water extract inhibits cell cycle G1/S transition by suppressing cyclin D1 expression and matrix-metalloproteinase-2 activity in human lung cancer cells

AIM OF THE STUDY

Scutellaria baicalensis Georgi is a widely used medicinal herb in several Asian countries including Korea. The various medicinal properties attributed to Scutellaria baicalensis include anti-bacterial, anti-viral, anti-inflammatory and anti-cancer effects. The present study investigated the cytotoxicity of Scutellaria baicalensis water extract (SBWE) on A549 non-small-cell-lung cancer cells and the A549 expression of cyclin D1, cyclin-dependent kinase 4 (CDK4) and matrix metalloproteinase-2 (MMP-2), and the effects of SBWE on cell cycle progression, especially the G1/S phase, and on cell motility.

MATERIALS AND METHODS

SBWE cytotoxicity was assessed by a standard colorimetric assay utilizing 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and expression of cyclin D1 and CDK4 protein in SBWE-treated A549 cells was assessed by Western blot analysis. Flow cytometry analysis was performed to determine the effect of SBWE on A549 cell cycle progression. A549 cell MMP-2 activity was examined by zymography. Cell motility and migration was assessed by a scratch wound healing assay.

RESULTS

SBWE was not cytotoxic. The production of Cyclin D1, CDK4 and MMP-2 activity were significantly decreased in a SBWE dose-dependent manner, with maximum inhibition occurring at SBWE concentrations of 250 μg/ml and 500 μg/ml. SBWE inhibited cell cycle progression in the G1/S phase and significantly inhibited the motility of A549 cells.

CONCLUSIONS

Cyclin D1 protein may be associated with MMP-2 activity and cell motility. Thus, SBWE promotes a strong protective effect against MMP-2 mediated metastasis and cell proliferation through the down-regulation of cyclin D1. SBWE may be a useful chemotherapeutic agent for lung cancer.