Role of arachidonic acid metabolites in tumor growth inhibition by nonsteroidal antiinflammatory drugs

Purpose: A murine model of squamous cell carcinoma (SCC) was used to determine the role of arachidonic acid (AA) metabolites in the growth of SCC of the head and neck. Materials and Methods: C3H/HeJ mice bearing SCC (SCC VII) were treated with cyclooxygenase inhibitors (piroxicam and nabumetone) or a 5-lipoxygenase inhibitor (ketoconazole). Growth curves were established, and final tumor weights were measured. Following sacrifice, tumor tissue homogenates were assayed for prostaglandin E2 (PGE2) and 12-hydroxyeicosatetraenoic acid (12-HETE) by enzyme-linked immunosorbent assay (ELISA), and leukotriene B4 (LTB4) by radioimmunoassay (RIA). Inflammatory cell infiltrate was assessed histologically. Results: A significant inhibition of tumor growth ( P = .001) and final tumor weight ( P = .002) was noted in mice treated with piroxicam and nabumetone. Inhibition of tumor growth was associated with increased tumor tissue levels of PGE2 ( P = .04) and lymphocytic infiltration ( P = .07). Significant inhibition of tumor growth ( P = .002) and final tumor weight ( P = .05) was also noted in mice treated with ketoconazole. Conclusion: These data suggest that both cyclooxygenase and lipoxygenase metabolites of AA affect tumor growth in this model and that inhibition of tumor growth by inhibitors of AA metabolism may be caused by an enhanced inflammatory cell response at the tumor site.