Abstract: Objective To evaluate expression of PAPP-A, IGF-I and the effect of TNF-α, IL-1β on the cytological functions of hCASMCs with IGF-I gene silencing after inflammatory factor, in order to further study on the action of IGF axis hormone in the rupture of astable atheroxclerosis plaque. Methods A RNA interference (RNAi） aimed at the gene of IGF-I was carried out to have an eukaryon transfection to hCASMCs. When the IGF-I-shRNA-hCASMC were treated by TNF-α, IL-1β, IGFBP4, the expression of PAPP-A and IGF-I were detected with Western blot and ELISA. And then, the effect of TNF-α,IL-1β,IGFBP4 on the proliferation of IGF-I-shRNA-hCASMC were assessed by MTT assay and changing in cell cycle and apoptosis were evaluated by using flow cytometry. Results Significant positive expression of PAPP-A in hCASMCs which were treated by TNF-α+IL-1β or TNF-α+IL-1β+IGFBP4 in Blank control (CON), Negative control (NC) and RNAi group were observed, but lower expression in the RNAi group than that in CON and NC groups. However, there was no positive expression of PAPP-A in hCASMCs of CON, NC, RNAi group treating without TNF-α+IL-1β or TNF-α+IL-1β+IGFBP4. The expression of IGF-I in hCASMCs of CON, NC, RNAi group treated with TNF-α+IL-1β+IGFBP4 were greater than that only with or without TNF-α+IL-1β treatment. In RNAi group, the A₅₇₀ decreased when the hCASMCs treated with TNF-α+IL-1β+IGFBP4 and significant lower than that in hCASMCs treated with TNF-α+IL-1β. When the hCASMCs were treated with TNF-α+IL-1β or TNF-α+IL-1β+IGFBP4, the rate of apoptosis significantly increased in RNAi group, which was significantly higher than that in CON group and NC group. In addition, in RNAi group, the rate of apoptosis in hCASMCs treated with TNF-α+IL-1β+IGFBP4 was significant higher than that in hCASMCs treated only with TNF-α+IL-1β. Conclusion When the IGF-I-shRNA-hCASMCs were stimulated by some inflammation factors, its proliferation decreased but the apoptosis enhanced. So the activated IGF-I level in local microebvironnment increased, which may cause the descend of cell proliferation and the increasing of apoptosis.