Cryptotanshinone inhibits lung tumor growth by increasing CD4+ T cell cytotoxicity through activation of the JAK2/STAT4 pathway.

Cryptotanshinone is one of the fat-soluble phenanthrene quinone components. In vitro studies have shown that tanshinone compounds can inhibit the proliferation of various tumor cells and affect cell cycle distribution. The aim of the present study was to better understand the effect of cryptotanshinone on the inhibition of small cell lung cancer by cytotoxic cluster of differentiation (CD)4+ T cells through activation of the Janus kinase 2/signal transducer and activator of transcription 4 (JAK2/STAT4) pathway. The Cell Counting kit-8 assay and the lactate dehydrogenase assay were used to analyze the cell proliferation of H446 and CD4+ T cells, and the cell cytotoxicity of CD4+ and CD8+ T cells, respectively. JAK2 and STAT4 protein expression was measured by western blot analysis. Cryptotanshinone effectively inhibited the tumor growth of the H446 cells and the cell proliferation of the CD4+ T cells. Treatment with cryptotanshinone increased the cytotoxicity of the CD4+ T cells, but could not affect the cytotoxicity of the CD8+ T cells. Meanwhile, cryptotanshinone induced phosphorylated (p)-JAK2 and p-STAT4 protein expression in the CD4+ T cells. These results suggest that cryptotanshinone inhibits the cell growth of lung tumors by increasing CD4+ T cell toxicity through activation of the JAK2/STAT4 pathway.