Angiogenesis is the process by which new blood vessels are formed. It is also a key feature in the growth and progression of several cancers. Studies have identified vascular endothelial factor (VEGF) as an important regulator of angiogenesis in both the physiological and pathological settings. In the context of cancer, VEGF signalling was shown to be impaired in several neoplasms. This discovery led to the development of therapies against VEGF. While antiangiogenic VEGF-targeted therapy has resulted in increased cancer patient survival, the development of resistance has necessitated the discovery of alternative or complimentary therapeutic strategies. Integrin-linked kinase (ILK) is an effector of integrin-mediated cell adhesion. It is also involved in the regulation of the PI3k/Akt pathway.
The effects of ILK knockdown and anti-VEGF were evaluated on endothelial cell proliferation using BRdU-labeling, and on migration and invasion using the xcelligence system. The effects of the combination treatment on vascular tumour growth were studied in C57BL/6 mice inoculated with sEnd.2 cells. The secretion of VEGF, platelet derived growth factor (PDGF) and basic fibroblast growth factor (bFGF) were measured employing ELISA.
ILK knockdown with siRNA and anti-VEGF treatment with DMH4 resulted in a more pronounced decrease in cell survival, proliferation and migration when compared to the individual treatments, even following VEGF induction. The combination treatment was also more potent in inhibiting angiogenesis in vitro. Western blot analysis revealed the suppression of Akt phosphorylation. Also, results revealed a decrease in the expression of HIF1-α and nitric oxide (NO), as well as a decrease in proangiogenic factors, namely, VEGF, PDGF and bFGF. In vivo, there was a significant reduction in tumor diameter in vascular tumor-bearing mice treated with Cpd 22, an inhibitor of ILK and DMH4 (n = 6 per group; P
Therefore, the combination approach may be useful in the elaboration of antiangiogenic therapy in vascular tumors, further studies are warranted.
Legal entity responsible for the study
National Research Foundation; University of Pretoria
All authors have declared no conflicts of interest.