The native structure of annexin A2 peptides in hydrophilic environment determines their anti-angiogenic effects

Abstract

The progression of aggressive cancer occurs via angiogenesis and metastasis makes these processes important targets for the development of anti-cancer agents. However, recent studies have raised the concern that selective inhibition of angiogenesis results in a switch towards increased tumour growth and metastasis. Since Annexin A2 (AnxA2) is involved in both angiogenesis and metastasis, it may serve as an ideal target for the simultaneous inhibition of both processes. Based on the discovery that domains I (D(I)) and IV (D(IV)) of AnxA2 are potent inhibitors of angiogenesis, we designed seven peptides derived from these domains based on AnxA2 crystal structures. The peptides were expressed as fusion peptides to increase their folding and solubility. Light scattering, far-UV circular dichroism and thermal transition analyses were employed to investigate their aggregation tendencies, α-helical propensity and stability, respectively. 2,2,2-trifluoroethanol (50%) increased the α-helical propensities of all peptides, indicating that they may favour a hydrophobic environment, but did not enhance their thermal stability. D(I)-P2 appears to be the most stable and folded peptide in a hydrophilic environment. The secondary structure of D(I)-P2 was confirmed by nuclear magnetic resonance spectra. The effect of the seven AnxA2 peptides on the formation and integrity of capillary-like networks was studied in a co-culture system mimicking many of the angiogenesis-related processes. Notably, D(I)-P2 inhibited significantly network formation in this system, indicating that the folded D(I)-P2 peptide interferes with vascular endothelial growth factor-dependent pro-angiogenic processes. Thus, this peptide has the potential of being developed further as an anti-angiogenic drug.

Long-term efficacy and downstream mechanism of anti-annexinA2 monoclonal antibody (anti-ANX A2 mAb) in a pre-clinical model of aggressive human breast cancer

“…We and others have previously shown that ANX A2 regulates neoangiogenesis and plays an important role in human breast tumor growth, invasion and metastasis [26,[79][80][81]. Before our report, clinical studies had demonstrated that neoangiogenesis is a significant and independent prognostic indicator in patients with early stage invasive breast cancer [44,45], suggesting a common link between ANX A2, neoangiogenesis and invasive breast cancer.…”

The novel model peptide, αAL14, regulates angiogenesis by inhibiting VEGFR 2-mediated signaling in HUVECs

“…inhibitory effect on formation of capillary-like networks rather than others (6) we expected that αAL14 which is assumed to contain α-helical structure has similar effects on endothelial cells. Moreover, there have been efforts to develop endogenous peptides that can penetrate into target cells across the cell membrane because the peptides have lower toxicity without drawbacks (3,5).…”

“…Raddum et al revealed that seven different model peptides based on Annexin A2 (AnxA2) present anti-angiogenic effects on HUVECs. Especially, a synthetic peptide D1-P2 adopting higher α-helical structure significantly inhibited network formation rather than the others in the co-culture system of HUVECs and SMCs (6). Therefore, in this study, in order to reveal whether peptides containing α-helical structure can affect angiogenesis, a novel cationic linear α-helical model peptide, αAL14, was used.…”

Anti-angiogenic agents for the treatment of solid tumors: Potential pathways, therapy and current strategies – A review

“… Anti-angiogenic agent Targeted pathway Clinical indications Ref. Bevacizumab Humanized monoclonal anti-VEGF-A antibody Several solid tumors such as, non-small cell lung cancer, renal cell cancer, colorectal cancer, ovarian cancer, breast cancer, cervical cancer and glioblastoma [88] Ziv-aflibercept Fusion protein directed against VEGF-A, VEGF-B and PlGF Metastatic colorectal cancer in combination with 5-FU, irinotecan and leucovorin [92] Sorafenib Multi-tyrosine kinase inhibitor Hepatocellular carcinoma, renal cell carcinoma, thyroid carcinoma [93] Sunitinib Multi-tyrosine kinase inhibitors Hepatocellular carcinoma, renal cell carcinoma, thyroid carcinoma [94] Axitinib Receptor tyrosine kinase inhibitor Advanced renal cell carcinoma [52] Nintedanib Receptor tyrosine kinase inhibitor Idiopathic pulmonary fibrosis [52] Regorafenib Receptor tyrosine kinase inhibitor Metastatic colorectal cancer, gastrointestinal stromal tumor and hepatocellular carcinoma [52] Pazobanib Receptor tyrosine kinase inhibitor Advanced renal cell carcinoma, advanced soft tissue sarcoma [52] Cabozantinib Receptor tyrosine kinase inhibitor Metastatic medullary thyroid cancer [52] Vandetanib Receptor tyrosine kinase inhibitor Medullary thyroid cancer [52] Thalidomide Inhibitor of Akt phosphorylation Multiple myeloma in combination with dexamethasone [95] , [96] …”

“…Some peptides, such as Annexin-A2 (Anx-A2), are known for their regulatory effects against VEGF-dependent angiogenesis. Purification of peptides such as Anx-A2, is currently under investigation to inhibit angiogenesis [93] , [94] .…”