Antiangiogenic activity of zinc and zinc-sorafenib combination using the chick chorioallantoic membrane assay: A descriptive study.

Aim: Zinc, a trace element, is known for downregulating several proangiogenic growth factors and cytokines. However, its antiangiogenic activity is not adequately studied. The present study was aimed to evaluate the possible antiangiogenic activity of zinc via the chick chorioallantoic membrane (CAM) assay. Furthermore, the antiangiogenic activity of the combination therapy of zinc with various doses of sorafenib, a tyrosine kinase inhibitor, was evaluated.

Materials And Methods: A pilot study was initially conducted so as to select suitable doses of zinc and sorafenib. The antiangiogenic activity after combining zinc 2.5 μg/embryo with sorafenib 1 and 2 μg/embryo was also evaluated. The antiangiogenic activity was quantified in terms of total length of blood vessels, number of junctions, number of branching points, and mean length of the blood vessels.

Results: Zinc 2.5 μg/embryo showed significant (P < 0.05) antiangiogenic activity, as compared to the control group. However, its effect was not comparable to that of sorafenib 2 μg/embryo. The combination of zinc 2.5 μg/embryo with sorafenib 2 μg/embryo did not show an additive/synergistic effect. The combination of zinc 2.5 μg/embryo with sorafenib 1 μg/embryo produced an antiangiogenic activity which was comparable (P > 0.05) to that of sorafenib 2 μg/embryo.

Conclusion: Zinc caused significant antiangiogenic activity in the CAM assay. The lack of addition/synergism in the zinc-sorafenib combination could have been due to the variability in the dose/ratio selection. Addition of zinc to sorafenib therapy could improve treatment tolerability, reduce cost of therapy, and reduce the emergence of drug resistance. Future mechanistic studies could identify the exact pharmacodynamics of zinc as an angiogenesis inhibitor.