The Effects Of Isoliquiritigenin On Anti-tumor Angiogenesis

Objective:Isoliquiritigenin (ISL),a simple chalcone-type flavonoid, which is derived from licorice compounds and mainly present in roots of licorice and many other plants, foods, beverages and tobacco.It has been reported to possess a wide range of potent biological and pharmacological activities including anti-oxidative, anti-tumor, anti-aging, anti-inflammatory, anti-diabetic activities and so on. However, the angiogenic effects of ISL have not been reported as yet. Therefore, the aim of this study was to investigate the effects of ISL on anti-tumor angiogenesis both in vitro and in vivo and its mechanism.Methods:In present study, we assessed the antiangiogenic activities of ISL on proliferation viability, migration and tube formation of human microvascular endothelial cell line-1(HMEC-1)for the first time in vitro.Moreover, we investigated the in vivo antiangiogenic activity of ISL on chicken embryos nap allantoic membrane model (CAM).In order to clarify the underlying molecular mechanism of ISL, we also investigated the signaling pathway involved in the angiogenesis process.The cells viability was assessed using the Sulforhodamine B (SRB)assay. Modified Boyden Transwell chamber assay was done to research the influence of ISL on HMEC-1cells migration.2’,7’-dichlorofluorescein diacetate (DCFH-DA), as fluorescent probe, was used to measure the levels of intracellular reactive oxygen species (ROS)which was induced by VEGF. MMP-2and MMP-9expressed by HMEC-1cells were assessed through Gelatin Zymography assay. HMEC-1cells cycle was detected by flow cytometry (FC).Results:ISL inhibited the growth of HMEC-1cells as well as SW620and A549cells in a time and concentration-dependent way. The results of modified Boyden chamber assay showed that ISL significantly and concentration-dependently suppressed the migration activity of HMEC-1cells.Tube sample structure formation, closely linked with the endothelial cells migration, has further confirmed the effect of ISL on anti-angiogenesis.Moreover, ISL also inhibited intracellular ROS levels induced by VEGF, the matrix metalloproteinase-2(MMP-2) and matrix metalloproteinase-9(MMP-9) expression by HMEC-1cells.Furthermore, ISL also induced endothelial cell apoptosis at a low dose(12.5μM/L) while its higher doses (25-100μM/L) blocked the cells in S phase of mitosis by flow cytometry. According to in vivo chicken embryos nap allantoic membrane angiogenesis model,we found that ISL distinctly inhibited the angiogenesis of chick embryos.Conclusion:In summary, our experimental results showed that SL can directly inhibit the proliferation of A549, SW620and HMEC-1cells and significantly suppress the activities of migration and tube-like formation of HMEC-1cells.Combined with inhibitory effect on tumor angiogenesis factor, it is concluded that ISL possesses anti-tumor angiogenic activities and it is worth to do some deeper research as an antitumor agent.