RESUMO
The sclerotium of Poria cocos Wolf, which grows on the roots of pine trees, has long been used as a sedative and diuretic (Chang and But, 1987). The accumulating data revealed that certain ingredients of the sclerotium of Poria cocos showed anti-tumor activities (Kanayama, 1986). Although the mechanism of anti-tumor activity is not known, the polysaccharides may potentiate the host defense mechanism through the activation of immune system. In the present study we show that PCSC22, a polysaccharide isolated from the sclerotium of Poria cocos with one percent sodium carbonate, significantly induces nitric oxide (NO) production and inducible NO synthase (iNOS) transcription. To further investigate the mechanism responsible for the induction of iNOS gene expression, we investigated the effect of PCSC22 on the activation of NF-kappaB/Rel, whose binding site was located in the promoter of iNOS gene. Immuno-histo-chemical staining of p65 and p50 showed that PCSC22 produced strong induction of NF-kappaB/Rel nuclear translocation. Electrophoretic mobility shift assay (EMSA) further confirmed the activation of NF-kappaB/Rel by PCSC22. In conclusion, we demonstrate that PCSC22 stimulates macrophages to express iNOS gene through the activation of NF-kappa B/Rel.