Identification of cyclin B1 as a shared human epithelial tumor-associated antigen recognized by T cells

We eluted peptides from class I molecules of HLA-A2.1(+) breast adenocarcin oma and loaded reverse phase high-performance liquid chromatography (HPLC) fractions onto dendritic cells to prime naive CD8(+) T cells. Fractions tha t supported growth of tumor-specific cytotoxic T lymphocytes were analyzed by nano-HPLC micro-ESI tandem mass spectrometry. Six HLA-A2.1-binding pepti des, four 9-mers (P1-P4) differing in the COOH-terminal residue, and two 10 -mers (P5 and P6) with an additional COOH-terminal alanine, were identified in one fraction. Peptide sequences were homologous to cyclin Bl. We printe d CD8(+) T cells from another HLA-A2.1(+) healthy donor with synthetic pept ides and generated P4-specific responses. We also detected memory T cells s pecific for one or more of these peptides in patients with breast cancer an d squamous cell carcinomas of the head and neck (SCCHN). T cells from one p atient, restimulated once in vitro, could kill the tumor cell line from whi ch the peptides were derived. Immunohistochemical analysis of tumor lines a nd tissue sections showed cyclin B1 overexpression and aberrant localizatio n in the cytoplasm instead of the nucleus. Sequencing genomic DNA and cDNA corresponding to P1-P6 region showed that differences in COOH-terminal resi dues were not due to either DNA mutations or errors in transcription, sugge sting a high error rate in translation of cyclin B1 protein in tumors.