Objective        To determine the effect of ursolic acid (UA) on NADPH oxidase (NOX)- Hedgehog (Hh) signaling pathway in hepatic stellate cells（HSCs）.       Methods        Culture-

activated HSC-T6 cells were divided into 6 groups: normal control group

leptin group (100 ng/mL)

UA group (50 μmol/L)

NOX inhibitor DPI (20 μmol/L) group

and the 2 intervention groups pretreated with UA or DPI followed by stimulation with leptin for different times. The mRNA expression of Shh

Smo and Gli1/2 was detected in above cells after 12 hours’ treatment by RT-PCR. The protein expression of Rac1 and Gli2 were analyzed in the cells in 24 h of treatment by Western blotting. The proliferation of HSC-T6 cells was detected in 12

24 and 48 h after treatment by MTT assay.       Results        RT-PCR analysis showed that Smo mRNA expression was increased when leptin stimulated HSC-T6 cells for 12 h (

P

0.05). The expression of Shh and Gli2 mRNA was also increased compared with normal control group

but without significant difference. UA pretreatment significantly down-regulated the mRNA expression of Shh

Smo and Gli2 compared with control and leptin group (all

P

0.05). Leptin

UA and DPI had no effect on Gli1 mRNA expression. The protein expression of Rac1 and Gli2 was increased when leptin stimulated HSC-T6 cells for 24 h (

P

0.01). UA pretreatment significantly down-regulated Rac1 and Gli2 protein expression compared with leptin group (all

P

0.01). MTT assay showed that leptin promoted the proliferation in HSC-T6 cells. After 12 hours’ pretreatment with UA

the cell growth was inhibited significantly than in leptin treated cells (

P

0.01) in a time-dependent manner.       Conclusion        UA inhibits the expression of Shh

Smo

Gli2 mRNA and down-regulates the expression of Gli2 protein in HSC-T6 cells. One mechanism of UA inhibiting cell proliferation is probably via its inhibiting NOX subunit Rac1 and then NOX-Hh signaling pathway.