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Updated: Jul 15, 2026
Analyzing Tumor and Tissue Distribution of Target Antigen Specific Therapeutic Antibody
Published on: May 16, 2020
Identification and characterization of tumor antigens by using antibody phage display and intrabody strategies
Anne-Laure Goenaga1, Yu Zhou, Christine Legay
1ENS Cachan Laboratoire de Biotechnologie et Pharmacologie Génétique Appliquée (LBPA), UMR CNRS 8113, 61 avenue du Président Wilson, 94235 Cachan Cedex, France.
Abstract:
To generate a panel of antibodies binding human breast cancers, a human single chain Fv phage display library was selected for rapid internalization into the SK-BR-3 breast cancer cell line. Thirteen unique antibodies were identified within the 55 cell binding antibodies studied, all of them showing specific staining of tumor cells compare to normal epithelial cells. Two of the antibodies bound the ErbB2 oncogene while 6 bound the tumor marker transferrin receptor (TfR). By developing a scFv immunoprecipitation method, we were able to use LC-MS/MS to identify the antigen bound by one of the antibodies (3GA5) as FPRP (prostaglandin F2alpha receptor-regulatory protein)/EWI-F/CD9P-1 (CD9 partner 1) an Ig superfamily member that has been described to interact directly with CD9 and CD81 tetraspanins and to be overexpressed in adherent cancer cell lines. Although the 3GA5 scFv had no direct anti-proliferative effect, intracellular expression of the scFv was able to knockdown CD9P-1 expression and could be used to further define the role of the tetraspanin system in proliferation and metastasis. Moreover, the 3GA5 scFv was rapidly internalized into breast tumor cells and could have potential for the targeted delivery of cytotoxic agents to breast cancers. This study is the proof of principle that the direct selection of phage antibody libraries on tumor cells can effectively lead to the identification and functional characterization of relevant tumor markers.
Insights
Researchers developed novel antibodies targeting human breast cancer cells. One antibody identified CD9 partner 1 (CD9P-1), a protein overexpressed in cancers, offering potential for targeted drug delivery.
Area of Science:
- Oncology
- Immunology
- Molecular Biology
Background:
- Developing targeted therapies for human breast cancer is crucial.
- Phage display libraries offer a method for identifying novel cancer-binding antibodies.
- Understanding tumor-specific antigens is key for effective cancer treatment.
Purpose of the Study:
- To generate and characterize novel antibodies that bind specifically to human breast cancer cells.
- To identify the antigens targeted by these antibodies and explore their functional roles.
- To assess the potential of these antibodies for targeted cancer therapy and diagnostics.
Main Methods:
- Utilized a human single-chain variable fragment (scFv) phage display library selected for rapid internalization into the SK-BR-3 breast cancer cell line.
- Employed scFv immunoprecipitation coupled with LC-MS/MS to identify antibody targets.
- Investigated the functional effects of antibody expression, including antigen knockdown and cellular internalization.
Main Results:
- Identified thirteen unique antibodies with specific staining for tumor cells over normal epithelial cells.
- Two antibodies targeted the ErbB2 oncogene, and six targeted the transferrin receptor (TfR).
- One antibody (3GA5) was identified as targeting prostaglandin F2alpha receptor-regulatory protein (FPRP)/CD9 partner 1 (CD9P-1), which is overexpressed in cancer cells. Intracellular expression of 3GA5 scFv reduced CD9P-1 levels.
Conclusions:
- Direct selection of phage antibody libraries on tumor cells is effective for identifying and characterizing tumor markers.
- The 3GA5 antibody and its target CD9P-1 offer potential for understanding cancer proliferation and metastasis.
- Internalized antibodies like 3GA5 hold promise for targeted delivery of cytotoxic agents to breast cancers.
