Ciência e terapia do câncer

Proteolytically-cleaved Fragments of Cell Surface Proteins Stimulate a Cytotoxic Immune Response Against Tumoractivated Endothelial Cells In vitro

Abstract

Elena E. Balashova and Petr G. Lokhov

Endothelial antigens that stimulate immune-mediated damage of tumor vessels represent possible targets for the development of antiangiogenic vaccines aimed at preventing the progression of solid tumors. Since antigens expressed on the cell surface are accessible targets for both humoral and cell-mediated immune responses, the ability to isolate extracellular protein fragments from endothelial cells by proteolytic digest is a proposed strategy for the creation of antiangiogenic vaccines. Human microvascular endothelial cells (HMEC) were isolated from an abdominal subcutaneous adipose tissue biopsy. Both non-activated endothelial cells (nHMEC) and tumor-activated endothelial cells (aHMEC) were obtained. HMEC lysate and cleaved fragments of cell surface proteins (FCSP) of HMEC had total protein concentrations of 135 µg/mL and 2 µg/mL, respectively. Despite this difference in concentration, FCSP were able to stimulate immune cells in cytotoxicity assays better than the HMEC lysate. Moreover, FCSP obtained from tumor-activated endothelial cells were able to stimulate an immune response toward tumor-activated endothelial cells. Based on these results, FCSP of endothelial cells appear to provide a comprehensive set of surface antigens that are able to induce targeted, immune-mediated cytotoxic effects against tumor endothelial cells. These findings represent a successful strategy to produce safe and pure antigens for the production of antiangiogenic vaccines.