Tanshinone IIA (TSIIA) represses the progression of non-small cell lung cancer by the circ_0020123/miR-1299/HMGB3 pathway.

Tanshinone IIA (TSIIA), a multi-pharmaceutical compound, has been demonstrated to have anti-tumor properties. This study explores the potential regulatory mechanism of TSIIA on non-small cell lung cancer (NSCLC) progression. The cytotoxicity of TSIIA was evaluated by MTT (3-(4,5-Dimethylthiazol-2-yl)-2,5-Diphenyltetrazolium Bromide) and LDH (lactate dehydrogenase) assays. Expression levels of circ_0020123 (hsa_circ_0020123) and microRNA-1299 (miR-1299) were assessed by quantitative real-time polymerase chain reaction (qRT-PCR). Cell proliferation, migration, invasion, and apoptosis were analyzed by MTT, colony formation, transwell, wound-healing, or flow cytometry assays. The relationship between miR-1299 and circ_0020123 or HMGB3 (high mobility group box 3) was verified by the dual-luciferase reporter and/or RNA immunoprecipitation (RIP) assays. Protein level of HMGB3 was measured by western blotting. The relationship between TSIIA and circ_0020123 was confirmed by xenograft assay. TSIIA reduced xenograft tumor growth in vivo and repressed proliferation, migration, invasion, and facilitated apoptosis of NSCLC cells in vitro. TSIIA reduced circ_0020123 and HMGB3 expression, whereas elevated miR-1299 expression in NSCLC cells. Circ_0020123 knockdown enhanced the repressive influence of TSIIA treatment on the malignancy of NSCLC cells in vitro and in vivo. Circ_0020123 sponged miR-1299 to regulate HMGB3 expression under TSIIA treatment. MiR-1299 inhibitor reversed circ_0020123 knockdown-mediated influence on malignant behaviors of NSCLC cells under TSIIA treatment. HMGB3 elevation offset the suppressive impact of miR-1299 mimic on the malignancy of NSCLC cells under TSIIA treatment. TSIIA curbed NSCLC progression by the circ_0020123/miR-1299/HMGB3 axis, manifesting that the TSIIA/circ_0020123/miR-1299/HMG regulatory network might be a potential treatment strategy for NSCLC.