Angiogenesis Probes

Integrins are heterodimeric transmembrane receptors for cell adhesion to extracellular matrix (ECM) proteins and play important roles in certain cell-cell adhesions. In addition, they make transmembrane connections to the cytoskeleton and activate many intracellular signaling pathways. Because of their role in tumor angiogenesis and progression, integrins have become important diagnostic and therapeutic targets. To date 24 distinct integrins are known, and among them, integrin α_vβ₃ is known to strongly involve in the regulation of angiogenesis. The α_vβ₃ is generally expressed in low levels on the epithelial cells and mature endothelial cells, but it is highly expressed in many solid tumors. The α_vβ₃ levels correlate well with the potential for tumor metastasis and aggressiveness, which make it an important biological target for development of antiangiogenic drugs and molecular imaging probes for early tumor diagnosis.

Cyclic tripeptide arginine-glycine-aspartate (RGD) is well-known to bind preferentially to α_vβ₃ integrin with high affinity. Cyclic RGD is an effective ligand for tumor targeting since integrin α_vβ₃ is overexpressed not only on tumoral endothelium but also on various cancer cells. Thus, targeting tumor cells or tumor vasculature by RGD-based strategies is a promising approach for delivering anticancer drugs or diagnostic agents. Cyclic RGD peptides are also able to bind α_vβ_5, α₅β_1, α₆β₄, α₄β₁, and α_vβ₆ integrins, which may help enhance their tumor uptake due to the increased receptor population. BioActs developed cRGDFlamma^® series as effective fluorescent probes for the detection of angiogenesis and tumor cells. The probes are made up of various fluorophores conjugated cyclic RGD. We offer cRGDFlamma^® series as in vivo fluorescent probes for imaging of blood vessels, tumors and angiogenesis.