Cryptotanshinone inhibits cellular proliferation of human lung cancer cells through downregulation of IGF-1R/PI3K/Akt signaling pathway

Lung cancer is one of the most commonly diagnosed malignancies worldwide. Cryptotanshinone (CPT) is a diterpene quinone compound extracted from natural plants and has been reported to have anticancer effects in several cancers including human lung cancer. However, the mechanism by which CPT acts to prevent lung cancer cell growth is largely unknown. In the present study, by using MTT assay, colony formation assay, wound healing and western blotting assays, the effects of CPT on the cell proliferation and migration of human lung cancer cells and the potential cellular signaling mechanisms were investigated. The data demonstrated that CPT exhibited anti-proliferative effects against A549 and H1299 cells. In parallel, the migration of A549 cells was also markedly inhibited by CPT treatment. Further study indicated that CPT not only inhibited the basal phosphorylation level of insulin-like growth factor 1 receptor (IGF-1R) and RAC-alpha serine/threonine-protein kinase (Akt), but also blocked IGF-1 induced IGF-1R and Akt phosphorylation. Finally, it was demonstrated that pretreatment with CPT inhibited IGF-1 induced cell proliferation of A549 and H1299 cells. In conclusion, the results of the present study indicated that CPT inhibits the proliferation and migration of lung cancer cells via a mechanism that involves inhibiting the IGF-1R-mediated phosphoinositide 3 -kinase/Akt signaling pathway. The data provides evidence that CPT could be developed as a potential therapeutic agent for the treatment of lung cancer.