Identification of HLA-A3-restricted CD8+ T cell epitopes derived from mammaglobin-A, a tumor-associated antigen of human breast cancer.
Mammaglobin-A is highly overexpressed in breast cancer cell lines and primary breast tumors. This pattern of expression is restricted to mammary epithelium and metastatic breast tumors. Thus, mammaglobin-A-specific T cell immune responses may provide an important approach for the design of breast cancer-specific immunotherapy. The purpose of our study was to define the T cell-mediated immune response to mammaglobin-A. We determined that the frequency of mammaglobin-A-reactive CD8+ and CD4+ T cells in breast cancer patients is significantly higher than that observed in healthy female controls using limiting dilution analyses (p = 0.026 and p = 0.02, respectively). We identified 8 mammaglobin-A-derived 9-mer peptides with the highest binding affinity for the HLA-A3 molecule (Mam-A3.1-8) using a computer-assisted analysis of the mammaglobin-A protein sequence. Subsequently, we determined that CD8+ T cells from breast cancer patients reacted to peptides Mam-A3.1 (23-31, PLLENVISK), Mam-A3.3 (2-10, KLLMVLMLA), Mam-A3.4 (55-63, TTNAIDELK) and Mam-A3.8 (58-66, AIDELKECF) using an IFN-gamma enzyme-linked immunospot assay. A CD8+ T cell line generated in vitro against HLA-A*0301-transfected TAP-deficient T2 cells loaded with these peptides showed significant cytotoxic activity against the Mam-A3.1 peptide. This CD8+ T cell line showed a significant HLA-A3-restricted cytotoxic activity against mammaglobin-A-positive but not mammaglobin-A-negative breast cancer cells. In summary, our study identified four HLA-A3-restricted mammaglobin-A-derived epitopes naturally expressed by breast cancer cells, indicating the immunotherapeutic potential of this novel antigen for the treatment and prevention of breast cancer.
Jaramillo
Andrés
A
Department of Surgery, Washington University School of Medicine, St. Louis, MO, USA.
Majumder
Kanchana
K
Manna
Partha P
PP
Fleming
Timothy P
TP
Doherty
Gerard
G
Dipersio
John F
JF
Mohanakumar
Thalachallour
T
D001943:Breast Neoplasms / Q000276:immunology*; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology*; D000939:Epitopes / Q000032:analysis; D005260:Female; D015791:HLA-A3 Antigen / Q000276:immunology*; D006801:Humans; D016056:Immunodominant Epitopes; D060785:Mammaglobin A; D009363:Neoplasm Proteins / Q000276:immunology*; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology; D014407:Tumor Cells, Cultured; D014598:Uteroglobin / Q000276:immunology*
D000939:Epitopes; D015791:HLA-A3 Antigen; D016056:Immunodominant Epitopes; D060785:Mammaglobin A; D009363:Neoplasm Proteins; C556448:SCGB2A2 protein, human; D014598:Uteroglobin