Tanshinone IIA inhibits proliferation and migration by downregulation of the PI3K/Akt pathway in small cell lung cancer cells

BackgroundSmall cell lung cancer (SCLC) is the most malignant lung cancer type. Due to the high rates of metastasis and drug resistance, effective therapeutic strategies remain lacking. Tanshinone IIA (Tan IIA) has been reported to exhibit anti-tumor activity. Therefore, this study investigated the ability and underlying mechanism of Tan IIA to inhibit the metastasis and proliferation of SCLC.MethodsH1688 and H446 cells were treated in vitro with Tan IIA (0, 1, 2 and 4 mu M) or LY294002 (10 mu M) for 24, 48, 72 h. H1688 and H446 cell migration was evaluated in wound healing and transwell migration assays. RNA-sequencing helped assess gene expression. BALB/c nude mice were injected with H1688 cells and treated with the Tan IIA group (10 mg/kg/day) or a control. Expression of E-cadherin, vimentin and PI3K/Akt signaling pathway proteins in tumors and H1688 was investigated by immunohistochemical analysis and western blot.ResultsTan IIA inhibited H1688 and H446 cell proliferation without inducing apoptosis and suppressed H1688 and H446 cell migration. E-cadherin expression was increased, while vimentin expression was reduced after administration of Tan IIA. RNA-sequencing revealed that some genes related with the PI3K/Akt signaling pathway were altered using Tan IIA treatment. Furthermore, western blot helped detect PI3K and p-Akt expression was also reduced by Tan IIA treatment. Tan IIA inhibited tumor growth in vivo. Moreover, Tan IIA increased tumoral expression of E-cadherin accompanied by PI3K and p-Akt downregulation.ConclusionTan IIA suppresses SCLC proliferation and metastasis by inhibiting the PI3K/Akt signaling pathway, thereby highlighting the potential of Tan IIA as a new and relatively safe drug candidate to treat SCLC.