A73: Plant-produced substance antibodies against HER2/neu oncoprotein

Background Human epidermal growth factor receptor-2 (HER2/nue) is overexpressed in breast cancer. It has been shown that HER2-targeted therapies have radically changed the outcome of HER2-positive breast cancer patients. The aim of this study was to develop the technique for preparation of recombinant anti-HER2/neu antibody from plants and to provide with the basic characteristics of the HER2/neu oncoprotein. Materials and Methods We have designed and synthesized viral vectors to transform Agrobacterium tumifaciens affinity, ion exchange and gel filtration chromatography were used to purify the antibody. The quality of the substance was confirmed by SDS–PAGE and ELISA. The biological activity was tested by immunofluorescent analysis. Results Antibodies were purified by affinity and ion exchange chromatography from the Agrobacterium tumifaciens leaves extracts. Gel filtration chromatography was used for final purification of the protein. Immunocytochemical staining was performed to test the functional activity of the plant-made antibodies. Here we also show that plant-made antibodies bind to HER2/neu receptors on the surface of human SK-BR-3 breast cancer cells as effectively as the diagnostic antibody A0485 (DAKO, Denmark). Flow cytometry analysis was used for quantitative estimation of recombinant anti-HER2/neu antibodies: from 75.7% to 98.3% cells bound the plant-made antibodies. The same data were obtained with trastuzumab. Conclusion Based on the data obtained, we conclude that plant-made antibodies inhibit HER2/neu+ breast cancer cell proliferation. Additional experiments are required to prove that trastuzumab and plant-made antibodies share full identity in their biological activity.