Cancer Immunity 6:12 (2006)

Physical interaction of two cancer-testis antigens, MAGE-C1 (CT7) and NY-ESO-1 (CT6)

Hearn J. Cho^1*,**, Otavia L. Caballero^2*, Sacha Gnjatic², Valéria C. C. Andrade³, Gisele W. Colleoni³, Andre L. Vettore⁴, Hasina H. Outtz¹, Sheila Fortunato², Nasser Altorki¹, Cathy A. Ferrera¹, Ramon Chua², Achim A. Jungbluth², Yao-Tseng Chen¹, Lloyd J. Old², and Andrew J. G. Simpson²

¹Weill Medical College of Cornell University, 1300 York Avenue, New York, NY 10021, USA
²Ludwig Institute for Cancer Research, New York Branch at Memorial Sloan-Kettering Cancer Center, 1275 York Avenue, New York, NY 10021, USA
³Escola Paulista de Medicina, Universidade Federal de Sao Paulo, Sao Paulo, SP, Brazil
⁴Ludwig Institute for Cancer Research, Sao Paulo Branch, Sao Paulo, SP, Brazil
^*These authors contributed equally to this work
^**Present address: NYU Cancer Institute, New York University School of Medicine, 550 First Avenue, New York, NY 10016, USA

Keywords: two-hybrid assay, MAGE-C1, NY-ESO-1, human, multiple myeloma, NSCLC, RT-PCR

Abstract

Cancer/testis (CT) antigens are the protein products of germ line-associated genes that are activated in a wide variety of tumors and can elicit autologous cellular and humoral immune responses. CT antigens can be divided between those that are encoded on the X chromosome (CT-X antigens) and those that are not (non-X CT antigens). Among the CT-X antigens, the melanoma antigen gene (MAGE) family, defined by a shared MAGE homology domain (MHD), is the largest. CT-X genes are frequently expressed in a coordinate manner in cancer cells, and their expression appears to be modulated by epigenetic mechanisms. The expression of CT-X genes is associated with advanced disease and poor outcome in different tumor types. We used the yeast two-hybrid system to identify putative MHD-interacting proteins. The MHD of MAGE-C1 (CT7) was used as bait to screen a human testis cDNA library. This study identified NY-ESO-1 (CT6) as a MAGE-C1 binding partner. Immunoprecipitation and immunofluorescence staining confirmed MAGE-C1 interaction with NY-ESO-1, and cytoplasmic co-localization of both proteins in melanoma cells. Co-expression of these two genes was found to occur in cancer cell lines from different origins, as well as in primary tumors (multiple myeloma and non-small cell lung cancer samples). This is the first report of direct interaction between two CT antigens and may be pertinent in the light of the frequently coordinated expression of these proteins.