Identification of immunodominant HLA-B7-restricted CD8+ cytotoxic T cell epitopes derived from mammaglobin-A expressed on human breast cancers.

Abstract

Mammaglobin-A (MGBA), a 10-kD protein, is over expressed in 80% of primary and metastatic human breast cancers. Breast cancer patients demonstrate high frequencies of CD8(+) cytotoxic T lymphocytes (CTL) specific to MGBA. Defining CD8(+) CTL responses to HLA class I-restricted MGBA-derived epitopes assumes significance in the context of our ongoing efforts to clinically translate vaccine strategies targeting MGBA for prevention and/or treatment of human breast cancers. In this study, we define the CD8(+) CTL response to MGBA-derived candidate epitopes presented in the context of HLA-B7, which has a frequency of 17.7% in Caucasian and 15.5% in African American populations. We identified seven MGBA-derived candidate epitopes with high predicted binding scores for HLA-B7 using a computer algorithm. Membrane stabilization studies with TAP-deficient T2 cells transfected with HLA-B7 indicated that MGBA B7.3 (VSKTEYKEL), B7.6 (KLLMVLMLA), B7.7 (NPQVSKTEY), and B7.1 (YAGSGCPLL) have the highest HLA-B7 binding affinities. Further, two CD8(+) CTL cell lines generated in vitro against T2.B7 cells individually loaded with MGBA-derived candidate epitopes showed significant cytotoxic activity against MGBA B7.1, B7.3, B7.6, and B7.7. In addition, the same CD8(+) CTL lines lysed the HLA-B7(+)/MGBA(+) human breast cancer cell line DU-4475 but had no significant cytotoxicity against HLA-B7(-) or MGBA(-) breast cancer cell lines. Cold-target inhibition studies strongly suggest that MGBA B7.3 is an immunodominant epitope. In summary, our results define HLA-B7-restriced, MGBA-derived, CD8(+) CTL epitopes with all of the necessary features for developing novel vaccine strategies against HLA-B7 expressing breast cancer patients.

• Authors: Haseeb Ilias Basha, Venkataswarup Tiriveedhi, Timothy P Fleming, William E Gillanders, T Mohanakumar
• Journal: Breast cancer research and treatment (Breast Cancer Res Treat) Vol. 127 Issue 1 Pg. 81-9 (May 2011) ISSN: 1573-7217 [Electronic] Netherlands
• PMID: 20544273 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't, Research Support, U.S. Gov't, Non-P.H.S.)

Chemical References

• Antibodies, Monoclonal
• Epitopes, T-Lymphocyte
• HLA-B7 Antigen
• Mammaglobin A
• Neoplasm Proteins
• SCGB2A2 protein, human
• Uteroglobin

Topics

• Antibodies, Monoclonal (immunology)
• Antibody Affinity (immunology)
• Antibody Specificity (immunology)
• Breast Neoplasms (immunology)
• CD8-Positive T-Lymphocytes (immunology)
• Cell Line, Tumor
• Cytotoxicity, Immunologic
• Epitopes, T-Lymphocyte (immunology)
• Female
• HLA-B7 Antigen (immunology)
• Humans
• Mammaglobin A
• Neoplasm Proteins (immunology)
• T-Lymphocytes, Cytotoxic (immunology)
• Uteroglobin (immunology)