The expression of IL-1 alpha and its effect on the cell growth were examined in six human oral squamous carcinoma cell lines. All the cell lines expressed IL-1 alpha mRNA and protein at various levels. Particularly, HSC-2 and HSC-3 cells showed high level of the mRNA expression and secreted large amounts of IL-1 alpha into the culture fluid. Scatchard plot analysis of IL-1 alpha binding revealed that HSC-2 cells had high-and low-affinity receptors, whereas IL-1 alpha receptors on HSC-3 cells were of undetectable level. The cell growth of HSC-2 and HSC-3 cells was stimulated by IL-1 alpha and inhibited by anti-IL-1 alpha antibody or IL-1 receptor antagonist. The expression of IL-1 alpha mRNA by these cell lines was induced by either IL-1 alpha, epidermal growth factor (EGF) or transforming growth factor alpha (TGF-alpha). On the other hand, IL-1 alpha promoted the mRNA expression of TGF-alpha and EGF receptor. These findings indicate that IL-1 alpha acts as an autocrine growth stimulator for oral squamous carcinoma cells in vitro and its interaction with EGF/TGF-alpha/receptor system may play a role in this enhanced growth by IL-1 alpha.

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