Aberrant Expression of p56lck in Primary Oral Cancer

Objective: To examine whether p56lck is expressed in primary oral cancer and whether cytotoxic T-lymphocyte precursors reactive to p56lck peptides are present in the peripheral blood mononuclear cells of these patients.Materials and Methods: Oral tissue specimens were surgically obtained from 54 patients with oral squamous cell carcinoma and 20 patients with benign oral tumours. Six oral squamous cell carcinoma cell lines were used (HSC-2, HSC-3, HSC-4, OSC-20, Ca9-22, and SAS). The expression of p56lck was investigated by reverse transcriptase-polymerase chain reaction and immunohistochemical staining, and the level of interferon-gamma in the peripheral blood mononuclear cells of 10 patients with oral squamous cell carcinoma evaluated by enzyme-linked immunosorbent assay to ascertain the presence of cytotoxic T-lymphocyte precursors reactive to p56lck peptides.Results: p56lck was expressed in 38.9% (21/54) of the 54 primary oral cancer specimens obtained, but not in the benign oral tumour cells adjacent to the surrounding T cells. Only type II transcripts were expressed in the peripheral blood mononuclear cells, whereas only type I transcripts were expressed in all oral squamous cell carcinoma tissues and cell lines. Peripheral blood mononuclear cells from 7 (70%) out of 10 patients with oral cancer produced interferon-gamma in response to p56lck-derived peptides in vitro, suggesting an immune response to aberrantly expressed p56lck in these patients.Conclusion: These results may provide insight into the immunopathology of oral cancer. Further studies that demonstrate the activity of p56lck peptide-specific cytotoxic T lymphocytes may lead to the development of vaccines specific to individual oral cancer patients.