Cancer Immunity 5:11 (2005)

Humoral and cellular immune responses against the breast cancer antigen NY-BR-1: Definition of two HLA-A2 restricted peptide epitopes

Dirk Jäger¹, Julia Karbach², Claudia Pauligk², Inka Seil¹, Claudia Frei¹, Yao-Tseng Chen³, Lloyd J. Old⁴, Alexander Knuth⁵, and Elke Jäger²

¹Medizinische Onkologie, Nationales Centrum für Tumorerkrankungen, Universitätsklinik Heidelberg, Im Neuenheimer Feld 350, D-69120 Heidelberg, Germany
²II. Medizinische Klinik, Krankenhaus Nordwest, Steinbacher Hohl 2-26, D-60488 Frankfurt, Germany
³Department of Pathology, Weill Medical College of Cornell University, 1300 York Avenue, New York, NY 10021, USA
⁴Ludwig Institute for Cancer Research, New York Branch at Memorial Sloan-Kettering Cancer Center, 1275 York Avenue, New York, NY 10021, USA
⁵Onkologische Klinik und Poliklinik, Universitätsspital Zürich, Rämistrasse 100, CH-8091 Zürich, Switzerland

Keywords: human, tumor antigens, NY-BR-1, mRNA, tissue distribution, HLA-A2, T lymphocyte epitope

Abstract

Cancer immunotherapy depends on the identification of tumor-specific target antigens that are predominantly expressed in cancer cells and not in normal tissues. Here, we report the cloning and the expression analysis of the differentiation antigen NY-BR-1 that we have identified in a previous SEREX (serological analysis of recombinant cDNA expression libraries) screening. The cloning of the full length NY-BR-1 sequence led to the prediction of an open reading frame of 4.2 kb, encoding a protein of 158.9 kDa. NY-BR-1 mRNA expression analysis revealed tissue-specific expression in normal testis and breast tissues, as well as in 70% of breast tumors. We now show that NY-BR-1 is also sporadically expressed in normal prostate and in 32% of prostate tumors. Furthermore, we were able to identify two HLA-A2 restricted NY-BR-1 epitopes (p158-167 and p960-968) that are recognized by CD8+ T cell clones (NW1100-CTL-7 and NW1100-CTL-43, respectively), as determined by ELISPOT analysis and tetramer staining. Cotransfection assays of COS-7 cells also demonstrated that these two peptides are naturally processed and presented on HLA-A2 molecules. The identification of these two naturally processed NY-BR-1-specific CD8+ T cell epitopes opens the perspective for active immunotherapy of HLA-A2 positive patients with NY-BR-1 expressing tumors.