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

BACKGROUND: Small 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. METHODS: H1688 and H446 cells were treated in vitro with Tan IIA (0, 1, 2 and 4 µM) or LY294002 (10 µM) 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. RESULTS: Tan 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. CONCLUSION: Tan 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.

Suppression of PERK/eIF2α/CHOP pathway enhances oridonin-induced apoptosis by inhibiting autophagy in Small-Cell lung cancer cells.

Chinese herbs have been used to treat small-cell lung cancer (SCLC) due to their low toxicity and significant efficacy. This study focused on oridonin, a natural compound extracted from Rabdosia rubescens, and aimed to investigate its potential antitumor activity on SCLC and to evaluate the synergistic effect of combining oridonin with other small molecules. In this study, oridonin exhibited a dual effect. At lower concentrations, it suppressed the cell viability of SCLC cells (H1688 and H446). At high concentrations, oridonin induced SCLC cell apoptosis, damaged HBE cells in vitro and compromised the function of the liver and heart in vivo. The lower concentration of oridonin induced autophagy by enhancing the expression of p62 and the LC3B-II/LC3B-I ratio. This phenomenon might be associated with the activation of the protein kinase RNA-like ER kinase (PERK)/eukaryotic initiation factor 2 alpha (eIF2α)/growth arrest and DNA damage-inducible gene 153 (CHOP/GAD153) pathway. Therefore, the combined effect of oridonin with GSK2606414 or 3- methyladenine increased apoptosis in SCLC cells and reduced tumor growth. A similar phenomenon was observed after oridonin was combined with p62 or CHOP RNA interference treatment. Simultaneously, the combination of oridonin and GSK2606414 exhibited therapeutic efficacy without manifesting adverse effects. Our findings suggest that oridonin at lower concentrations can induce autophagy by activating the PERK/eIF2α/CHOP signaling pathway. The inhibition of the PERK/eIF2α/CHOP pathway could enhance oridonin therapeutic responses by triggering apoptosis. The novel therapeutic approach of combining oridonin with a PERK inhibitor is promising as a strategy for the treatment of SCLC.