Objective: To investigate the regulatory effect of curcumin on expression of signal transducer and activatorof transcription 3 (STAT3) in skin squamous cell carcinoma tissues as well as possible mechanisms of curcuminin prevention and treatment of skin squamous cell carcinoma. Materials and
Methods: Highly invasive A431cells were treated with curcumin at various doses .The cytotoxic effects of treatment with 5, 10, 15, 20, 25, 30, 35,40 and 50 umol/L curcumin for 24, 48 and 72 hours on A431 cells were measured by MTT assay. The invasioncapacity of cells treated with 5, 10 and 15 umol/L curcumin was measured by Transwell test, while adhesiveability was assessed by cell adhesion assay. The effects of 5,10 and 15 umol/L curcumin on expression levels ofSTAT3 were determined by Western blotting and on transcription levels of STAT3 mRNA by RT-PCR.
Results:Treatment with curcumin at a doses of more than 15 umol/L for more than 24 hour inhibited the growth of A431cells in a time-and dose-dependent fashion (p<0.001). The doses of 15 umol/L and less for 24 hours showed nosignificant cytotoxic effects on the cells, survival rates being more than 85%.The invasion and adhesive abilitiesdecreased gradually with the increasing curcumin concentration, 15 umol/L exerting the strongest inhibitoryeffects (p<0.05). Curcumin showed significant dose-dependent inhibitory effects on the transcription level ofSTAT3 mRNA (p<0.05).
Conclusions: Curcumin may reduce the invasive ability of A431 cells by inhibiting theactivation of STAT3 signal pathway and expression of STAT3 as a target gene in the pathway.