Identification of Tyrosine Kinases Overexpressed in Head and Neck Cancer

Objective: To identify protein-tyrosine kinases (PTKs) that may be involved in the development and progression of head and neck squamous cell carcinoma (HNSCC). Design: Messenger RNA from 7 HNSCC specimens was reverse transcribed to complementary DNA, and selective amplification of PTK complementary DNA was achieved using polymerase chain reaction (PCR) with degenerate PTK primers. The resulting PTK PCR products from these 7 HNSCC specimens were then cloned and randomly selected for sequencing. The PTKs that were represented multiple times in these randomly selected clones were selected as candidate PTKs that may be overexpressed in HNSCC. Antibodies against these candidate PTKs were then used for immunohistochemical studies on 8 other HNSCC specimens not used in the original selection of the candidate PTKs. Results: Three known (EphAl, Brk, and Ron) and 2 novel (KIAA0728 and KIAA0279) PTKs were found to be highly expressed in the 7 HNSCC samples studied, based on the technique of reverse transcriptase-PCR with degenerate primers. Immunohistochemical studies with antibodies against the 3 known PTKs in 8 other HNSCC specimens not used in the previous reverse transcriptase-PCR reaction demonstrated overexpression of EphAl, Brk, and Ron in 12.5%, 37.5%, and 75% of these specimens. Conclusions: In this study, we identified 5 PTKs that were overexpressed in HNSCC using a reverse transcriptase-PCR technique and confirmed the overexpression of 3 known PTKs in some of the 8 archival HNSCC specimens studied. Our finding suggests that the signaling pathways mediated through EphAl, Brk, and Ron may be involved in the development and progression of HNSCC.