Cyclic chalcone analogue KRP6 as a potent modulator of cell proliferation: an in vitro study in HUVECs.

In the present investigation a novel series of chalcone analogues were synthesized and evaluated for their anti-proliferative activity in human umbilical vein endothelial cells (HUVECs). Among 14 tested compounds, chalcone analogue (E)-3-(2'-methoxybenzylidene)-4-chromanone (KRP6) exhibited the most potent activity with IC50 19 µM. Moreover, HUVECs exhibited divergent, even opposing concentration-dependent responses to KRP6. This compound was the most potent inhibitor of cell proliferation and extracellular matrix formation (fibronectin and type IV collagen) at higher concentrations (20-50 µM). In contrast, KRP6 stimulated the compensatory increase in proliferative activity including extracellular matrix formation at low concentrations (1, 10 µM). KRP6 concentration-dependently modulated phosphorylation of Akt and mitogen-activated protein kinases such as extracellular signal-regulated kinase-1/-2 and p38 kinase, suggesting that these pathways play a role in the effect mediated by this compound. In addition, we found a selective effect on activated endothelial cells, in particular with resting endothelial cells. In conclusion, KRP6 is a potent modulator of selected steps of the angiogenic process in vitro. Accordingly, further in vivo research should be performed to facilitate its use in clinical practice.

Antiproliferative and antiangiogenic properties of horse chestnut extract.

This study was designed to examine the in vitro antiproliferative effect of the horse chestnut extract (HCE) on cancer cell lines. Furthermore, we have investigated the in vitro effect of HCE on some angiogenic events by using human umbilical vein endothelial cells. The cell proliferation was evaluated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay and anchorage-independent growth by colony-forming assay. To understand the growth inhibitory effects, carcinoma cell lines (Jurkat, CEM, HeLa, and MCF-7) were treated with various concentrations of HCE. Incubation of Jurkat, CEM, HeLa, and MCF-7 cancer cells with HCE at 125 µg/mL for 72 h caused 93.7%, 32.3%, 20.4% and 40.4% reduction in cell survival. Colony-forming assay also confirmed growth-inhibitory effects of the compound studied. In HeLa HCE-treated cells, we found a significant increase in cells having sub-G(0) /G(1) DNA content which is considered to be a marker of apoptotic cell death. Apoptosis was also further confirmed by DNA fragmentation analysis.Furthermore, HCE inhibited migration of human umbilical vein endothelial cells as well as decreased secretion of matrix metalloproteinase and vascular endothelial growth factor.In conclusion, the present study has assessed the in vitro antiproliferative/antiangiogenic potential of HCE. These results generate a rationale for in vivo efficacy studies with horse chestnut in preclinical cancer models.

In vitro toxicity of camalexin derivatives in human cancer and non-cancer cells.

The aim of the study was to investigate the cytotoxic activity of camalexin and its five synthetic derivatives in cancer and non-cancer cells. In cancer cells the benzocamalexin (BC) displayed the most potent activity with an IC value of 23.3-30.1 µmol/L. On the other hand, minimal toxicity (IC>100.0 µmol/L) in non-cancer cells was observed. Based on these results, BC was selected for further studies. Flow cytometric analysis revealed a BC-induced arrest of the cell cycle in the G2 phase associated with downregulation of α-tubulin, α1-tubulin, ß5-tubulin expression. These findings suggest that the inhibitory effect of BC is mediated via inhibition of microtubule formation. Moreover, BC downregulated the expression of microtubule-related protein indicating the effect of this compound on microtubule assembly. After treatment with BC increase of the sub-G DNA content fraction was noted which is considered to be a marker of apoptotic cell death. Apoptosis was also confirmed by DNA fragmentation assay. Moreover, quantitative real-time PCR showed that BC downregulated the expression of antiapoptotic genes Bcl-2 and Bcl-xL and upregulated the expression of proapoptotic Bax. Taken together, our study suggests that the blockade of cell cycle progression and initiation of apoptosis may play an important role in the antiproliferative activity of BC in human cancer cells.

Anti-angiogenic activity of the flavonoid precursor 4-hydroxychalcone.

Angiogenesis, the growth of new blood vessels, is necessary for cancerous tumors to keep growing and spreading. Suppression of abnormal angiogenesis may provide therapeutic strategies for the treatment of angiogenesis-dependent disorders. In the present study, we describe the in vitro and in vivo anti-angiogenic activities of the flavonoid precursor 4-hydroxychalcone (Q797). This chalcone (22µg/ml) suppressed several steps of angiogenesis, including endothelial cell proliferation, migration and tube formation without showing any signs of cytotoxicity. Moreover, we found a selective effect on activated endothelial cells, in particular with resting endothelial cells and the human epithelial tumor cell lines (HeLa, MCF-7, A549). In addition, Q797 was able to modulate both vascular endothelial growth factor (VEGF)- and basic fibroblast growth factor (FGF)- induced phosphorylation of extracellular signal-regulated kinase (ERK)-1/-2 and Akt kinase. It did not influence the nuclear translocation of p65 subunit of the nuclear factor-κB (NF-κB) when human endothelial cells were stimulated with tumor necrosis factor (TNF)-α. Taken together this indicates that the Q797-mediated inhibition of in vitro angiogenic features of endothelial cells is most likely caused by suppression of growth factor pathways. The potent inhibitory effect of Q797 on bFGF-driven neovascularization was also demonstrated in vivo using the chick chorioallantoic membrane (CAM) assay. In summary, this chalcone could serve as a new leading structure in the discovery of new potent synthetic angiogenesis inhibitors.