Granzyme B-VEGF receptor-binding peptide fusion protein expressed in B. longum induces apoptosis of KDR-positive cells / 南方医科大学学报

ABSTRACT

<p><b>OBJECTIVE</b>To express granzyme B-vascular endothelial growth factor (VEGF) receptor-binding peptide (GrB-VRB) fusion protein in Bifidobacteria longum (B. longum) and investigate the effects of this fusion protein on the proliferation and apoptosis of cells expressing VEGF receptor II, the kinase domain receptor (KDR).</p><p><b>METHODS</b>The recombinant expression vectors pBBADx-VRB, pBBADx-GrB and pBBADx-GrB-VRB were separately transformed into B. longum cells by electroporation. The expressed products were identified by enzyme-linked immunosorbent assay and Western blotting, and their effects on KDR-positive cells were analyzed using proliferation assay and TUNEL assay.</p><p><b>RESULTS</b>The expressed products were detected in both the supernatant and cellular fractions of B. longum cells. The recombinant GrB-VRB fusion protein reacted with such KDR-positive cells as human umbilical vein endothelial cells (HUVEC) and mouse colon cancer cell line CT-26, and caused obvious cell proliferation inhibition, cytotoxicity and cell apoptosis in these cells.</p><p><b>CONCLUSION</b>The recombinant GrB-VRB fusion protein secreted by the engineered B. longum cells can induce KDR-positive cell death as the result of GrB-induced cell apoptosis following the cell recognition by VRB.</p>