OBJECTIVETo investigate the effect of Hedgehog-Gli1 signaling pathway on proliferation, apoptosis and activation of hepatic stellate cells (HSCs) in vitro.

METHODSThe expression of Shh, Smo, Ptc and Gli-1 in HSC-T6 cells was analyzed by RT-PCR. HSC-T6 cells were incubated with various concentration of cyclopamine (0, 50, 100, 150, 200, 250 mumol/L) for 24 hours, cell viability was checked by MTT colorimetric assay, cell cycle was analyzed by flow cytometry, apoptosis was assayed by agarose electrophoresis of DNA and PI-Annexin V fluorescent staining, and the mRNA levels of Gli-1, TGF beta 1, PDGF and Bcl-2 were quantified by real-time RT-PCR.

RESULTSRT-PCR indicated that the components of the Hedgehog-Gli1 signaling pathway were expressed in HSC-T6 cells. MTT assay indicated that cyclopamine inhibited cell viability in a concentration dependant manner (F = 636.81, P less than 0.01). Flow cytometry indicated that cells were piled up at G0/G1 phase in cyclopamine treated cells (65.08%+/-1.50%) as compared to control cells (55.41%+/-2.54%, t = -8.05, P less than 0.01). Cyclopamine treatment resulted in apoptosis as indicated by DNA fragmentation and PI-Annexin V staining. The mRNA levels of Gli-1, TGF beta 1, PDGF and Bcl-2 in cyclopamine treated cells were significantly lower than that in control cells (P less than 0.01).

CONCLUSIONCyclopamine may inhibit the Hedgehog-Gli1 signaling, and hence repress proliferation and promote apoptosis in hepatic stellate cells.