Expression and immunogenicity of MAGE-3 and MAGE-6 in squamous cell carcinoma of the head and neck

Abstract

Problem: Development of adjuvant cancer immunotherapy in head and neck squamous cell carcinoma (HNSCC). Methods: The MAGE gene family, collectively referred to as cancer-testis antigens to describe their restricted expression pattern in tumor tissues, have been successfully targeted through immunotherapy of melanoma. Expression of MAGE-3 and -6 have been documented in up to 60% of HNSCC tumors, but a quantitative evaluation of expression and T cell immunogenicity of these proteins in HNSCC have not been performed. Further, the determinants of MAGE expression in primary and metastatic HNSCC cells has not been specifically addressed. Results: Frozen HNSCC lesions (25 primary tumors and 17 cervical metastases) were microdissected from cryostat tissue sections. Using a novel quantitative RT-PCR (qRT-PCR) assay, we evaluated the expression of MAGE-3 and -6, as well as HLA A2.1, in these tissues and in 10 HNSCC cell lines. T cell recognition of the HLA A2.1-restricted MAGE-3271-279 peptide was studied in HNSCC cell lines using the Interferon-g ELISPOT. Conclusion: MAGE-3 or -6 is expressed frequently and at variable levels in HNSCC tumors and was detected in over 50% of HNSCC cell lines and tissues in our study. Importantly, expression was retained at high levels in metastatic tumor-positive nodes. CD8+ T cells specific for a cross-reactive MAGE-3271-279 peptide have detectable T cell reactivity against MAGE-positive HNSCC cell lines but not against MAGE-negative cells. MAGE-3271-279 loaded tetrameric HLA A2.1 molecules can be used to quantify these T cells in the peripheral blood of HNSCC patients. MAGE3 also appears to be a potentially useful marker of metastatic tumor deposits in cervical nodes. Significance: MAGE-3 and -6 appear to be promising targets for T cell immunotherapy of cancer patients, including those with HNSCC. Our study relates quantitative expression levels of these tumor antigens with their potential as immunotherapeutic targets, using functional assays and strategies for enhancing expression of MAGE gene expression in tumor cells. Support: FAMRI Clinical Investigator Award (RLF)