Abstract: Objective: To study the expressions and clinical significances of interleukin-24 (IL-24) in the oral squamous cell carcinoma (OSCC). Methods: The protein and gene expressions of IL-24 were detected respectively by immunohistochemistry and real-time polymerase chain reaction (real-time PCR) technique method in 75 cases of OSCC patients and 30 cases of controls with normal oral mucosa tissues. The relationship between IL-24 expressions and the clinicopathologic features was analyzed. Results: Immunohistochemical staining showed that the positive expressions of IL-24 in the OSCC (45.33%, 34/75) were significantly lower than those of normal oral mucosa tissue (70.00%, 21/30)(P=0.022). The expressions of IL-24 were closely associated with the differentiation degree (P=0.002), lymph node metastasis (P=0.033) and clinical stage (P=0.035), but they were not correlated with the gender (P=0.917), age (P=0.812), smoking history (P=0.720), drinking history (P=0.847), and the site of lesion (P=0.959). Real-time PCR was used to detect the gene expressions of IL-24 in different pathological differentiation period of OSCC and in normal oral mucosa tissues. The average expressions of IL-24 in highly differentiated OSCC were 0.688, in moderately differentiated OSCC were 0.302, and in poorly differentiated OSCC were 0.153. All of them were lower than the average expressions of IL-24 in normal oral mucosa tissues, which were 1.000 (P<0.001). Conclusion: The expressions of IL-24 in OSCC were lower than that in normal oral mucosa tissues. This gene has certain correlation with clinical information.

Key words: Oral squamous cell carcinoma, Interleukin-24, Immunohistochemistry, Real-time PCR