Identification of potential therapeutic targets in human head & neck squamous cell carcinoma.

BACKGROUND: Human head and neck squamous cell carcinoma (HNSCC) is an aggressive and recurrent malignancy. Identification of unique or overexpressed cell-associated or cell surface antigens is critical for diagnosis and development of cancer vaccines and targeted therapies for HNSCC. We have used high throughput microarray technology to search for candidate targets in HNSCC. METHODS: Gene expression profiling in 17 HNSCC tumors and 3 normal tonsil tissues was performed by microarray. QRT-PCR analysis was performed to validate the microarray results. The five candidate genes were further characterized by immunohistochemical technique in surgical samples and tissue arrays. RESULTS: A total of 192 up-regulated genes at statistical significance of p < 0.01 and log2 ratio > or = 1 were identified in HNSCC tumors compared to normal tissues. These genes belong to immune response, cell growth, cell cycle regulation, oncogenes, metabolism and others. Five potential novel target genes (FABP5, CD24, CD44, CD74, and HSP27) were identified, which were highly expressed in HNSCC tumor samples and tissue arrays. CD24, CD44, and CD74 proteins were expressed on the cell surface, and FABP5 and HSP27 proteins were predominantly expressed in the cytoplasm of HNSCC. CONCLUSION: Five genes and their products may serve as a diagnostic biomarker or therapeutic target for HNSCC. While additional work is needed to elucidate the biological significance of these proteins, CD24 and CD74 expressed only in small proportion of cells indicating tumor heterogeneity and subtypes of tumor initiating cells (CD24+/CD44+) present in HNSCC.