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Cancer/testis antigens: structural and immunobiological properties
Alexei F Kirkin1, Karine N Dzhandzhugazyan, Jesper Zeuthen
1Department of Tumor Cell Biology, Institute of Cancer Biology, Danish.
Abstract:
Characterization of tumor-associated antigens recognized by cytotoxic T lymphocytes which has evolved during recent years opens new possibilities for specific anti-cancer immunotherapy. Among different groups of tumor-associated antigens, cancer/testis (CT) antigens (expressed in many tumors and among normal tissues only in testes) represent the most perspective antigens for immunotherapy because of their broad tumor-specific expression. More than 50 CT antigens have been described so far and, for many of them, epitopes recognized by T lymphocytes have been identified. The most studied group of CT antigens is the MAGE proteins, which form the so-called MAGE superfamily, together with some MAGE-like proteins that have a different distribution than classical CT antigens. The MAGE superfamily includes five families: MAGE-A, MAGE-B, MAGE-C, MAGE-D, and necdin. Comparison of the structure of members of MAGE superfamily points to the existence of a domain organization of these proteins. The central, core domain (second domain) is highly conservative. The first domain is homologous among MAGE family members with a CT expression, but unique for each member of the MAGE-D and necdin families. In addition to the homology of the central domain, the third domain is also homologous among all members of MAGE superfamily, but to a much lesser extent. The MAGE-D proteins contain an additional, fourth domain, which in the case of MAGE-D3 coincides with trophinin, a separate molecule described previously as an adhesion molecule that participates in embryo implantation. The structural classification of the members of MAGE superfamily might help in the future to understand the biological function of MAGE proteins. One important property of the CT antigens is the up-regulation of their expression by DNA demethylating agents, indicating a possible mechanism for their re-expression in tumors. One of the implications of this particular property could be that a combination of immunotherapy targeting CT antigens with chemotherapy inducing up-regulation of CT antigens might result in more efficient tumor eradication.
Insights
Cancer/testis (CT) antigens, like MAGE proteins, are promising targets for cancer immunotherapy due to their tumor-specific expression. Combining CT antigen immunotherapy with chemotherapy may enhance tumor eradication.
Area of Science:
- Immunology
- Oncology
- Molecular Biology
Background:
- Tumor-associated antigens recognized by cytotoxic T lymphocytes are crucial for anti-cancer immunotherapy.
- Cancer/testis (CT) antigens exhibit broad tumor-specific expression, making them ideal targets.
- The MAGE protein superfamily, a prominent group of CT antigens, includes five families with distinct structural and expression patterns.
Purpose of the Study:
- To characterize tumor-associated antigens, focusing on cancer/testis (CT) antigens and the MAGE superfamily.
- To explore the structural organization and potential biological functions of MAGE proteins.
- To investigate the implications of CT antigen properties for novel anti-cancer immunotherapy strategies.
Main Methods:
- Structural comparison of MAGE superfamily members to identify conserved and unique domains.
- Analysis of CT antigen expression patterns in tumors and normal tissues.
- Review of existing literature on MAGE proteins, CT antigens, and immunotherapy.
Main Results:
- The MAGE superfamily comprises five families (MAGE-A, -B, -C, -D, necdin) with a conserved central domain and variable flanking domains.
- MAGE-D proteins possess a unique fourth domain, with MAGE-D3 coinciding with the adhesion molecule trophinin.
- CT antigens, including MAGE proteins, can be upregulated by DNA demethylating agents.
Conclusions:
- Structural classification of MAGE superfamily members aids in understanding their biological functions.
- The ability of CT antigens to be re-expressed by demethylating agents suggests a synergistic approach.
- Combining CT antigen-targeted immunotherapy with chemotherapy that upregulates CT antigens may lead to more effective tumor eradication.