N-Acetyl-cysteine modulates inducible nitric oxide synthase gene expression in human hepatocytes

AM3 inhibits LPS-induced iNOS expression in mice

We have analyzed the effect of a patented glycoconjugate of natural origin, AM3 (commercially available under the name Inmunoferon) in the expression of iNOS induced by administration of LPS in mice. We have observed that oral treatment with the drug daily for 6 days reduced the levels of expression of iNOS induced by an intravenous pulse of LPS. This effect was significant in the lungs and kidneys, but it was much more marked in the liver. In addition, the levels of nitric oxide in serum were clearly decreased upon treatment with AM3. Together, these results suggest that AM3 modulates the nitric oxide response and points to a possible role for AM3 in the control of the inflammatory response.

Transcription activation of Inducible Nitric Oxide Synthase gene in different cell lines

AIM: To investigate the transcription activation of inducible nitric oxide synthase (iNOS) gene in different cell lines.

METHODS: The coding sequence of iNOS promoter (iNOSp) was amplified by PCR from genomic DNA of human hepatoblastoma cell line HepG₂, and cloned into pEGM-Teasy vector to yield Teasy- iNOSp. The iNOSp gene was cut from Teasy-iNOSp by KpnI and XhoI, and then subcloned into pCAT3-Basic to produce a construct named pCAT3-iNOSp. pCAT3-iNOSp was transfected into HepG₂ cell line, SMMC-7721 human hepatocellular carcinoma cell line, NIH-3T3 mouse fibroblast cell line, Ito human lipocyte cell line, and L02 human normal liver cell line by FuGENE 6 transfection reagent. Cells transfected with pCAT3-Basic or pCAT3-Promoter were used as negative and positive controls. The activity of CAT, which reflects the transcription activation of the iNOS gene promoter, was detected by ELISA after 48 hours of transfection.

RESULTS: The report vector pCAT3-iNOS was successfully constructed, as confirmed by restriction enzyme digestion and sequencing. The activity of CAT was highest in HepG₂ cells transfected with pCAT3-iNOSp, and lowest in Ito cells.

CONCLUSION: The iNOS gene promoter can transactivate its downstream genes. Its transcription activity varies in different cell lines.