Overexpression of Interleukin-18 Induces Growth Inhibition, Apoptosis and Gene Expression Changes in a Human Tongue Squamous Cell Carcinoma Cell Line

OBJECTIVE: To investigate the role of interleukin-18 (IL-18) in regulating the growth of the human tongue squamous cell carcinoma cell line CRL-1623™. METHODS: The human IL18 gene was cloned and transfected into CRL-1623™ cells using the transfection vector pcDNA3.1(+). Investigations included analysis of cell viability, detection of apoptosis using annexin V-fluorescein isothiocyanate, assessment of caspase 3/7 activity and real-time reverse transcription-polymerase chain reaction to assess expression of the IL18, CCND1 (cyclin D(1)), CCNA1 (cyclin A(1)) and IFNG (interferon-γ) genes. RESULTS: Introduction of the IL18 gene inhibited cell proliferation at 24, 48 and 72 h after transfection compared with untransfected cells and cells transfected with blank pcDNA3.1(+) vector. Apoptotic cell numbers and caspase 3/7 activity were significantly enhanced by IL18 transfection. Levels of IL18 and IFNG mRNA were elevated and CCND1 mRNA was reduced after 48 h in IL18 transfected cells compared with wild-type cells. CONCLUSIONS: These findings suggest that IL-18 plays a role in the regulation of tongue squamous cell carcinoma and may represent a potential therapeutic target.