Intrabody targeting vascular endothelial growth factor receptor-2 mediates downregulation of surface localization.

Angiogenesis is among the most important mechanisms that helps cancer cells to survive, grow and undergo metastasis. Therefore, inhibiting angiogenesis will suppress tumor growth. Vascular endothelial growth factor (VEGF) and its receptor (VEGFR) are believed to be important players of angiogenesis. The goal of this study was to evaluate the success of a novel nanobody against VEGFR2 in tethering its target inside the endoplasmic reticulum and preventing its transport to the cell membrane. Nanobody sequence was cloned in a mammalian vector in fusion with green fluorescent protein and a KDEL retention signal. After transfection of 293KDR cells with this expression vector, surface localization of VEGFR2 was monitored by flow cytometry. This study demonstrates that our intrananobody is effective in targeting VEGFR2 receptor, and therefore, it is a powerful tool to downregulate a surface-exposed target protein, and in this capacity, it has potential to be used as a therapeutic protein to inhibit growth of tumors.