Anti-Angiogenic Activity of Flunarizine by In Ovo, In Vitro, and In Vivo Assays

Objectives

The involvement of T-type calcium channels in cell proliferation and the role of sodium channels in cell migration have been extensively studied in angiogenesis. In the present study, flunarizine, a dual sodium/calcium channel blocker; was selected to evaluate its anti-angiogenic potential. This can be therapeutically beneficial in diseases caused by pathologically excessive angiogenesis.

Materials and Methods

The anti-angiogenic activity of ion channel blocker was screened by chick chorioallantoic membrane assay (in ovo), rat aortic ring assay, endothelial cell proliferation assay, transwell migration assay, Matrigel cord-like morphogenesis assay (in vitro), and sponge implantation method (in vivo). The anti-angiogenic activity of the test drug was compared with the standard anti-angiogenic drug bevacizumab and, in addition, the test responses were compared with the angiogenic factor vascular endothelial growth factor at a maximal concentration of 500 pM.

Results

All the groups were compared with the control group using one-way ANOVA, followed by a post hoc test, Dunnett's test, to compare the mean of all the groups with the control mean. In the chick chorioallantoic membrane assay, the number of branching points and angiogenic score were evaluated and significant results were observed at 10^-5 M and 10^-4 M. In the aortic ring assay a reduction in the area of sprouts was observed with 5-10 μM and significant reductions in the weight of sponges, number of blood vessels formed, and hemoglobin content were observed at all three tested concentrations of flunarizine in the sponge implantation method. In the studies on human umbilical vein endothelial cells the test drug (1-100 nM) showed significant inhibition of proliferation and migration and a decrease in the network length of cord-like tubes in a dose-dependent manner.

Conclusion

Flunarizine has significant anti-angiogenic action by inhibiting cell proliferation, migration, and cord-like tube formation, which resulted from blocking of the T-type calcium and sodium channels. Further studies on the structural modifications of flunarizine for repurposing this ion channel modulator will lead to treatment of the diseases due to excessive angiogenesis from the root cause.

Ethyl-p-methoxycinnamate isolated from Kaempferia galanga inhibits inflammation by suppressing interleukin-1, tumor necrosis factor-α, and angiogenesis by blocking endothelial functions

OBJECTIVE

The present study aimed to investigate the mechanisms underlying the anti-inflammatory and anti-angiogenic effects of ethyl-p-methoxycinnamate isolated from Kaempferia galanga.

METHODS

The anti-inflammatory effects of ethyl-p-methoxycinnamate were assessed using the cotton pellet granuloma assay in rats, whereby the levels of interleukin-1 and tumor necrosis factor-α were measured in the animals' blood. In addition, the levels of interleukin, tumor necrosis factor, and nitric oxide were measured in vitro using the human macrophage cell line (U937). The analgesic effects of ethyl-p-methoxycinnamate were assessed by the tail flick assay in rats. The anti-angiogenic effects were evaluated first by the rat aortic ring assay and, subsequently, by assessing the inhibitory effects of ethyl-p-methoxycinnamate on vascular endothelial growth factor, proliferation, migration, and tube formation in human umbilical vein endothelial cells.

RESULTS

Ethyl-p-methoxycinnamate strongly inhibited granuloma tissue formation in rats. It prolonged the tail flick time in rats by more than two-fold compared with the control animals. The inhibition of interleukin and tumor necrosis factor by ethyl-p-methoxycinnamate was significant in both in vivo and in vitro models; however, only a moderate inhibition of nitric oxide was observed in macrophages. Furthermore, ethyl-p-methoxycinnamate considerably inhibited microvessel sprouting from the rat aorta. These mechanistic studies showed that ethyl-p-methoxycinnamate strongly inhibited the differentiation and migration of endothelial cells, which was further confirmed by the reduced level of vascular endothelial growth factor.

CONCLUSION

Ethyl-p-methoxycinnamate exhibits significant anti-inflammatory potential by inhibiting pro-inflammatory cytokines and angiogenesis, thus inhibiting the main functions of endothelial cells. Thus, ethyl-p-methoxycinnamate could be a promising therapeutic agent for the treatment of inflammatory and angiogenesis-related diseases.

Murine 5T multiple myeloma cells induce angiogenesis in vitro and in vivo

Multiple myeloma is a B cell malignancy. Recently, it has been demonstrated that bone marrow samples of patients with multiple myeloma display an enhanced angiogenesis. The mechanisms involved seem to be multiple and complex. We here demonstrate that the murine 5T multiple myeloma models are able to induce angiogenesis in vitro by using a rat aortic ring assay and in vivo by determining the microvessel density. The rat aortic rings cultured in 5T multiple myeloma conditioned medium exhibit a higher number of longer and more branched microvessels than the rings cultured in control medium. In bone marrow samples from 5T multiple myeloma diseased mice, a statistically significant increase of the microvessel density was observed when compared to bone marrow samples from age-matched controls. The angiogenic phenotype of both 5T multiple myeloma cells could be related, at least in part, to their capacity to produce vascular endothelial growth factor. These data clearly demonstrate that the 5T multiple myeloma models are good models to study angiogenesis in multiple myeloma and will allow to unravel the mechanisms of neovascularisation, as well as to test new putative inhibitors of angiogenesis.