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Identification of tyrosinase-related protein 2 as a tumor rejection antigen for the B16 melanoma
M B Bloom1, D Perry-Lalley, P F Robbins
1Surgery Branch, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892, USA.
Abstract:
Recently, major advances have been made in the identification of antigens from human melanoma which are recognized by T cells. In spite of this, little is known about the optimal ways to use these antigens to treat patients with cancer. Progress in this area is likely to require accurate preclinical animal models, but the availability of such models has lagged behind developments in human tumor immunology. Whereas many of the identified human melanoma antigens are normal tissue differentiation proteins, analogous murine tumor antigens have not yet been identified. In this paper we identify a normal tissue differentiation antigen, tyrosinase-related protein 2 (TRP-2), expressed by the murine B16 melanoma which was found by screening a cDNA library from B16 with tumor-reactive cytotoxic T lymphocytes (CTL). A peptide conforming to the predicted MHC class I H2-Kb binding motif, TRP-2181-188, was identified as the major reactive epitope within TRP-2 recognized by these anti-B16 CTLs. By site-directed mutagenesis, it was shown that alteration of this epitope eliminated recognition of TRP-2. It was further demonstrated that a CTL line raised from splenocytes by repeated stimulation in vitro with this peptide could recognize B16 tumor and was therapeutic against 3-d-old established pulmonary metastases. The use of TRP-2 in a preclinical model of tumor immunotherapy may be helpful in suggesting optimal vaccination strategies for cancer therapy in patients.
Insights
Researchers identified tyrosinase-related protein 2 (TRP-2) as a key antigen in murine melanoma. A specific TRP-2 peptide demonstrated therapeutic potential in preclinical models, offering insights for cancer immunotherapy strategies.
Area of Science:
- Immunology
- Oncology
- Biochemistry
Background:
- Advances in identifying human melanoma antigens recognized by T cells have outpaced the development of preclinical models.
- Optimal strategies for utilizing tumor antigens in cancer treatment remain largely unknown.
- Analogous murine tumor antigens to human differentiation proteins have not been identified, hindering preclinical research.
Purpose of the Study:
- To identify a normal tissue differentiation antigen in murine melanoma recognized by T cells.
- To characterize the specific epitope within this antigen responsible for T cell recognition.
- To evaluate the therapeutic potential of targeting this antigen in a preclinical cancer immunotherapy model.
Main Methods:
- Screening a cDNA library from B16 melanoma with tumor-reactive cytotoxic T lymphocytes (CTLs).
- Identifying a specific peptide (TRP-2181-188) as the major reactive epitope using predicted MHC class I binding motifs.
- Employing site-directed mutagenesis to confirm the epitope's role in antigen recognition.
- Generating and testing a CTL line against B16 melanoma and pulmonary metastases.
Main Results:
- Tyrosinase-related protein 2 (TRP-2), a normal differentiation antigen, was identified in B16 melanoma.
- The peptide TRP-2181-188 was confirmed as the primary epitope recognized by anti-B16 CTLs.
- Site-directed mutagenesis demonstrated that altering this epitope abolished TRP-2 recognition.
- A CTL line targeting TRP-2181-188 showed therapeutic efficacy against established pulmonary metastases in vivo.
Conclusions:
- TRP-2 is a relevant target antigen for murine melanoma immunotherapy.
- The identified TRP-2 epitope and corresponding CTLs offer a promising preclinical model for cancer therapy research.
- This model may inform the development of optimal vaccination strategies for human cancer immunotherapy.