Objective: To observe effect of realgar nanoparticles (RN) on inhibiting proliferation and inducting apoptosis for human skin squamous cell carcinoma A431 cells

and to explore the related mechanism. Method: MTT colorimetric method and flow cytometric were used to observe the influence of RN on proliferation and apoptosis for human skin squamous cell carcinoma A431 cell

and RT-PCR was used to detect the affect of RN on the expression of survivin and Caspase-3. Result: MTT assay and flow cytometry technique showed that RN could induce apoptosis in the A431 cells and inhibit their proliferation; and the effects were increased with the dose of RN. The combination of RN with cisplatin showed synergistic effect. In the control group

the 5%

10% and 20% RN groups

DDP group and DDP+10% RN group

survivin relative expression levels were (68.74±1.96)%

(63.93±3.57)%

(57.12±3.93)%

(47.64±6.44)%

(41.44±4.83)% and (32.18±4.10)% accordingly;while the Casepase-3 relative expression levels were (26.26±2.07)%

(32.660±4.42)%

(35.29±5.26)%

(38.52±8.37)%

(45.69±4.19)% and (52.98±6.52)% respectively. RN could increase the expression of Caspase-3 and reduce the expression of survivin. Conclusion: RN may play an anti-tumor effect by inducing tumor cell apoptosis and inhibiting their proliferation; the mechanism may be related to the increase in Caspase-3 expression and the down-regulation of the expression of survivin.