Gene transfer of IL-27 to tumor cells has been proven to inhibit tumor growth in vivo by antiproliferation, antiangiogenesis, and stimulation of immunoprotection. To investigate the nonimmune mechanism of IL-27 that suppresses lung cancer growth, we have established a single-chain IL-27-transduced murine Lewis lung carcinoma (LLC-1) cell line (LLC-1/scIL-27) to evaluate its tumorigenic potential in vivo. Mice inoculated with LLC/scIL-27 displayed retardation of tumor growth. Production of IL-12, IFN-gamma, and cytotoxic T cell activity against LLC-1 was manifest in LLC/scIL-27-injected mice. Of note, LLC-1/scIL-27 exhibited decreased expression of cyclooxygenase-2 (COX-2) and PGE(2). On the cellular level, the LLC/scIL-27 transfectants had reduced malignancy, including down-regulation of vimentin expression and reduction of cellular migration and invasion. The suppression of tumorigenesis by IL-27 on lung cancer cells was further confirmed by the treatment with rIL-27 on the murine LLC-1 and human non-small cell lung carcinoma (NSCLC) cell lines. PGE(2)-induced vimentin expression, movement, and invasiveness were also suppressed by the treatment with rIL-27. Our data show that IL-27 not only suppresses expression of COX-2 and PGE(2) but also decreases the levels of vimentin and the abilities of cellular migration and invasion. Furthermore, inoculation of LLC/scIL-27 into immunodeficient NOD/SCID mice also exhibited reduced tumor growth. Our data indicate that IL-27-induced nonimmune responses can contribute to significant antitumor effects. Taken together, the results suggest that IL-27 may serve as an effective agent for lung cancer therapy in the future.