Stat1 deficiency in the host enhances interleukin-12-mediated tumor regression.

Signal transducer and activator of transcription 1 (Stat1) is considered a key transcription factor that inhibits tumorigenesis, and Stat1 activation in the host is required for interleukin-12 (IL-12)-mediated generation of CTL activity. Using syngeneic Stat1-/- C3H mice bearing SCCVII tumors in this study, we discovered opposite results. Stat1 deficiency in the host significantly enhances IL-12-mediated tumor regression, resulting in tumor eradication from 60% of SCCVII tumor-bearing mice and significant inhibition of tumor growth when compared with control treatment (P < 0.