ObjectiveTo investigate the effect of icaritin on the small cell lung cancer cell lines NCI-H446 and its mechanism. MethodsThe NCI-H446 cells at logarithmic growth phase were divided into control and icaritin groups. The cells in the control group were normally treated and cells in the icaritin group were incubated with icaritin (8 μmol/L). Thiazole blue and flow cytometry were used to examine the proliferation and apoptotic changes in the two groups 48 hours after incubation respectively. Gene expression of Janus kinase 2 (JAK2) and signal transducers and activators of transcription 3 (STAT3) were detected by real-time quantitative polymerase chain reaction. The changes of JAK2, STAT3, phospho-JAK2 (p-JAK2), phospho-STAT3 (p-STAT3), Bax and BCL-2 protein were detected by Western blotting. ResultsCompared with the control group, the proliferation rate of NCI-H446 cells in the icaritin group was significantly lower (P<0.05), but the apoptotic rate of NCI-H446 cells in the icaritin group was significantly higher (P<0.05). After the treatment with icaritin, the expression of JAK2 and STAT3 mRNA had no obvious differences. The Western blotting results showed that there was no significant changes in total JAK2, STAT3 protein (P>0.05), but an increasing trend in p-JAK2, p-STAT3 and Bax was observed with the decreasing of BCL-2 (P<0.05). ConclusionIcaritin can inhibit the proliferation and promote the apoptosis of NCI-H446 cells and the effect may be achieved through JAK2/STAT3 signal transduction pathway.