RESUMO
Despite the increasing number of available therapeutic methods, the prognosis of nonsmall cell lung cancer (NSCLC) remains poor. Furthermore, side effects are an important limiting factor in the treatment of NSCLC. Therefore, developing an efficacious, safe, affordable and easily accessible chemotherapeutic agent is necessary for NSCLC treatment. As a natural chemical produced by Zingiberaceae plants, curcumin exerts distinct antitumor effects on several tumor types. In the present study, curcumin was observed to inhibit not only cell proliferation and cell cycle transition, but also cell migration in NSCLC, as determined by a series of experiments (such as MTS assay, colony formation assay, flow cytometric analysis, Transwell migration assay and western blotting). Mechanistically, curcumin induced G2/M phase arrest by controlling cell cycle and epithelialmesenchymal transition (EMT)related checkpoints. Furthermore, curcumin significantly inhibited the expression of Tolllike receptor 4 (TLR4)/MyD88 and EGFR in a dose and timedependent manner. Conversely, EGF reversed the inhibitory action of curcumin on TLR4/MyD88. In clinical specimens, TLR4 and MyD88 were highly expressed in NSCLC tissues, and a significant positive association was observed between TLR4 and MyD88 expression. These data suggested that curcumin may control the EGFR and TLR4/MyD88 pathways to synergistically downregulate downstream cell cycle and EMTrelated regulators, in order to block cell proliferation and metastasis in NSCLC. These findings provide evidence for the clinical application of curcumin.
