Identification of epitope regions recognized by tumor inhibitory and stimulatory anti-ErbB-2 monoclonal antibodies: implications for vaccine design.
The self-oncoprotein ErbB-2 is overexpressed in a number of malignancies. The presence of endogenous anti-ErbB-2 Ab and T cell immune responses to this protein in cancer patients has made ErbB-2 an attractive target for active immunization. However, the finding that murine anti-ErbB-2 Abs can have stimulatory, inhibitory, or no effects on cancer cell growth suggests that an inappropriately induced immune response may have an adverse effect. To ensure the induction of a beneficial Ab response, it is important to identify the epitopes recognized by these Abs. In this study we have used phage-displayed ErbB-2 gene fragment libraries and synthetic peptides to epitope-map a panel of anti-ErbB-2 mAbs. The epitopes of three mAbs, N12, N28, and L87, were successfully located to C531-A586, T216-C235, and C220-C235 of ErbB-2, respectively. It was found that while N12 inhibited tumor cell proliferation, N28 stimulated the proliferation of a subset of breast cancer cell lines overexpressing ErbB-2. The peptide region recognized by N12, (C531-A586; EP531), was used as an immunogen to selectively induce an inhibitory immune response in mice. Mice immunized with the GST fusion peptide (GST-EP531) recognized the peptide region EP531 as well as native ErbB-2. More importantly, Igs purified from mouse sera were able to inhibit up to 85% of tumor cell proliferation. In conclusion, our study provides direct evidence of the function-epitope relationship of anti-ErbB-2 Abs and also emphasizes the value of inducing a potent tumor inhibitory polyclonal Ab response by rationally selecting regions of ErbB-2 used for immunization.
Yip
Y L
YL
School of Medicine, University of New South Wales, Sydney, New South Wales, Australia.
Smith
G
G
Koch
J
J
Dübel
S
S
Ward
R L
RL
D000595:Amino Acid Sequence; D000818:Animals; D000911:Antibodies, Monoclonal / Q000378:metabolism* / Q000494:pharmacology; D000912:Antibodies, Neoplasm / Q000378:metabolism* / Q000494:pharmacology; D000951:Antigens, Neoplasm / Q000235:genetics / Q000276:immunology* / Q000378:metabolism; D000970:Antineoplastic Agents / Q000378:metabolism / Q000494:pharmacology; D001667:Binding, Competitive / Q000276:immunology; D001943:Breast Neoplasms / Q000276:immunology / Q000473:pathology; D019496:Cancer Vaccines / Q000138:chemical synthesis / Q000235:genetics / Q000276:immunology*; D005260:Female; D015723:Gene Library; D006131:Growth Inhibitors / Q000378:metabolism* / Q000494:pharmacology; D006133:Growth Substances / Q000378:metabolism* / Q000494:pharmacology; D006801:Humans; D007106:Immune Sera / Q000096:biosynthesis; D007274:Injections, Intraperitoneal; D051379:Mice; D008807:Mice, Inbred BALB C; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D010449:Peptide Mapping; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000235:genetics / Q000276:immunology* / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000008:administration & dosage / Q000276:immunology; D014407:Tumor Cells, Cultured
D000911:Antibodies, Monoclonal; D000912:Antibodies, Neoplasm; D000951:Antigens, Neoplasm; D000970:Antineoplastic Agents; D019496:Cancer Vaccines; D006131:Growth Inhibitors; D006133:Growth Substances; D007106:Immune Sera; D010446:Peptide Fragments; D018719:Erb-b2 Receptor Tyrosine Kinases; D011993:Recombinant Fusion Proteins