Abstract: The Wilm's tumor suppressor gene is one of the important tumor suppressor factors correlated with liver tissue functional abnormalities. The human inducible nitric oxide synthase(hiNOS) has important biological functions via catalyzing the production of nitric oxide(NO), which is a signal modulator involved in various immune response, chronic inflammations, as well as carcinogenesis. The roles of Wilm's tumor suppressor(WT1) in the regulation of hiNOS was reported in this paper. We inserted hiNOS promoter to pGL3-basic vector carrying luciferase gene and got the plasmid p8.3iNOS, which was used as a report system for the study of the relationship between WT1 and the hiNOS promoter activity. The results from the luciferase assay demonstrate that WT1 could suppress the transcription of hiNOS gene in two hepatoma derivative cells lines, HepG2 and Hep3B. Moreover, the alternative splicesomes of WT1 had different effects on the inhibition of hiNOS expression among which the alternative splicing form WT1(-/-) had the strongest inhibitory effect on hiNOS in a dose-dependent manner. Western blot assay reveals that over-expressed WT1(-/-) down-regulated the expression of hiNOS protein in HepG2 cell. These results suggest that WT1 could control the expression of hiNOS in transcriptional level.

Key words: Wilm’s tumor suppressor(WT1), Human inducible nitric oxide synthase(hiNOS), Alternative splicesome, Transcriptional regulation