A novel flavonoid isolated from Sophora flavescens exhibited anti-angiogenesis activity, decreased VEGF expression and caused G0/G1 cell cycle arrest in vitro.

Kushen, the dried root of Sophora flavescens Ait, is a traditional Chinese herbal medicine. Kushen alkaloids have been developed in China as anticancer drugs, and more potent antitumor activities have been identified in kushen flavonoids than in kushen alkaloids. In this study, the anti-angiogenic properties of (2S)-7,2',4'-triihydroxy-5-methoxy-8-dimethylallyl flavanone (Compound 1, a novel flavonoid isolated from Kushen), were examined using the human umbilical vein endothelial cell line (ECV304) in vitro. The results indicated that compound 1 shows anti-angiogenesis activity via inhibitory effects on cell proliferation, cell migration, cell adhesion, and tube formation. Further studies indicated that compound 1 blocks cell cycles in the G0/G1 phase without inducing apoptosis, and down regulates vascular endothelial growth factor (VEGF) expression. The free radical scavenging activity of compound 1 was found through 2',7'-dichlorofluorescin diacetate (DCFH-DA) incubation assay in cells. The anti-angiogenic properties of compound 1 and its antiproliferative effect on endothelial cells without causing apoptosis make it a good candidate for development as a agent against development of tumors.

[Gossypol acetic acid induces DNA double-strand breaks in human mucoepidermoid carcinoma cell MEC-1].

The present study was conducted to investigate the effects of gossypol acetic acid (GAA) on the proliferation of human mucoepidermoid carcinoma cell line MEC-1 in vitro and its possible molecular mechanisms of DNA double-strand breaks (DSB). MTT assay was performed to test the inhibition of proliferation of MEC-1 cells by GAA. DSB and γH2AX foci formation induced by GAA were detected by neutral comet assay and immunostaining. GAA (5-40 µmol/L) inhibited the growth of MEC-1 cells in a dose- and time-dependent manner. One of the indexes of comet assay, percentage of head DNA was decreased, however other indexes, including tail length, percentage of tail DNA, tail moment (TM) and Olive tail moment (OTM) were increased when treated with 2.5- 40 µmol/L GAA for 24 h or 20 µmol/L GAA for 3-48 h, compared with those in control. The percentage of γH2AX-positive cells was also increased when MEC-1 was treated with 2.5-20 µmol/L GAA for 24 h or 20 µmol/L GAA for 3-48 h, compared with that in control. All these results show that GAA inhibits the proliferation of MEC-1, and DSB maybe one of the mechanisms of inhibitory effect of GAA on the growth of tumor cells.

Type IV pili of Acidithiobacillus ferrooxidans are necessary for sliding, twitching motility, and adherence.

We used conventional methods to investigate the mechanism by which Acidithiobacillus ferrooxidans colonizes a solid surface by assessing pili-mediated sliding, twitching motility, and adherence. A. ferrooxidans slided to form circular oxidized zones around each colony. This suggested that slide motility occurs through pili or flagella, though A. ferrooxidans strains ATCC 19859 and ATCC 23270 lack flagella. The results of reverse transcription-PCR demonstrated that the putative major pili gene of A. ferrooxidans strains ATCC 19859, ATCC 23270, and BY3 genes were transcribed. Culture of A. ferrooxidans between silicone gel and glass led to the production of type IV pili and the formation of rough twitching motility zones. When the bacteria were grown on lean ore cubes, pyrite was colonized readily by A. ferrooxidans and there is a correlation between pilus expression and strong attachment. However, non-pili bacteria attached minimally to the mineral surface. The results show a correlation between these functions and pilus expression.

Biphasic regulation of angiogenesis by reactive oxygen species.

Reactive oxygen species (ROS) are believed to be important molecules in the regulation of angiogenesis. However, direct evidence is obtained from hydrogen peroxide only. The comparison of superoxide anion (O2-), hydrogen peroxide (H202) and hydroxyl radical (HO*) effects on angiogenesis in one angiogenic model were studied. Tube formation, migration and adhesion of endothelial cells were enhanced with a low concentration of O2 generated by 500 [microM xanthine (X) and 1 mU/ml xanthine oxidase (XO), but significantly inhibited as the XO increased to 10 mU/ml or more. Low concentrations of H2O2 (0.01-1 microM) induced tube formation and the maximal tube formation was achieved at 0.1 microM which also induced cell migration and adhesion, while high concentrations of H2O2 (100 microM) inhibited tube formation and cell migration. Both H2O2 and O2 inhibited cell proliferation at high concentration only. HO* at low concentration neither inhibited nor stimulated the tube formation, cell proliferation and migration but inhibited at high concentration. The effects of O2 were significantly abolished by catalase (CAT) alone or in combination with superoxide dismutase (SOD), but not by inactive CAT or SOD alone. Active CAT, but not inactive CAT, also reversed the effects of H2O2. Pretreatment with GSH effectively reversed the inhibitory effects of HO*. Therefore, our results suggest that ROS have biphasic effects on angiogenesis, which indicated that pharmacologically regulating cellular ROS levels might serve as an anti-angiogenic or angiogenic principles. They also provide a theoretical basis for the development and rational use of novel angiogenic and anti-angiogenic drugs.

Rosmarinic acid inhibits angiogenesis and its mechanism of action in vitro.

Rosmarinic acid (RA), a water-soluble polyphenolic compound with anti-oxidative and anti-inflammatory activities, inhibited several important steps of angiogenesis including proliferation, migration, adhesion and tube formation of human umbilical vein endothelial cells (HUVEC) in a concentration-dependent manner. RA also reduced intracellular reactive oxygen species (ROS) level, H2O2-dependent VEGF expression and IL-8 release of endothelial cells. These findings suggested that the anti-angiogenic potential of RA might be related to its anti-oxidative activity, which further resulted in the inhibition of ROS-associated VEGF expression and IL-8 release.