Abstract: Objective To observe the effect of IPI-926 on the proliferation of human colon cancer HT-29 cells and to investigate the effect of IPI-926 on the expression of Hedgehog signaling pathway in human colon cancer HT-29 cell proliferation. Methods Human colon cancer HT-29 cells were cultured in vitro, randomly set the blank control group and different concentrations (10, 20, 30 nM) IPI-926 intervention group. The intervention time of colorectal cancer cell was 72 h. The morphological changes were observed by inverted microscope. Effects of different concentrations of IPI-926 after the intervention of 72 h on the proliferation of HT-29 cells was determined by MTT assay and the apoptotic rate calculated. Reverse transcription PCR(RT-PCR) and Western blot were used to detect the expression of Shh, Ptch, Smo and Gli-1 mRNA and its related proteins in HT-29 cells after 72 hours of culture. The independent samples t-test was used for comparison between groups, and P< 0.05 was considered statistically significant. Results Apoptosis of HT-29 cells treated with different concentrations of IPI-926 (10, 20, 30 nM) increased when compared with the control, and the apoptosis rate increased with the increase of IPI-926 concentration. The inhibitory rates of IPI-926 (10, 20 and 30 nM) on human colon cancer cell line HT-29 were (17.23±1.32)%, (38.34±1.82)% and (75.81±3.43)%, respectively, rose with the increase of the concentration of IPI-926, showed a dose-effect relationship. The expression of Shh, Ptch, Smo and Gli-1 mRNA and protein were not significantly different between the blank control group and the IPI-926 concentration of 10 nM. However, the mRNA and protein expression of Shh, Ptch, Smo and Gli-1 were significantly down-regulated at IPI-926 concentration of 20 nM and 30 nM as compared with blank control group. And the expression of Shh, Ptch, Smo and Gli-1 at IPI-926 at 30 nM was significantly higher than that at 20 nM. Conclusion Low dose IPI-926 cannot effectively inhibit the proliferation of HT-29 cells, but 20 nM or more can effectively inhibit the proliferation of HT-29 cells. The mechanism of its inhibition may be related to the expression of Shh, Ptch, Smo and Gli-1 related to Hh pathway.