Inhibitory effects of andrographolide on migration and invasion in human non-small cell lung cancer A549 cells via down-regulation of PI3K/Akt signaling pathway

Lung cancer is the leading cause of death among cancers worldwide and non-small cell lung cancer (NSCLC) comprises more than 80% of lung cancer cases. Treatment options for patients with advanced NSCLC have evolved in the last decade with the advent of novel biological agents. Andrographolide, a diterpenoid lactone isolated from a traditional herbal medicine Andrographis paniculata, is known to have the potential to be developed as a chemotherapeutic agent. In order to understand the anti-cancer properties of andrographolide, we examined its effect on migration and invasion in human NSCLC A549 cells. The results of wound-healing assay and in vitro transwell assay revealed that andrographolide inhibited dose-dependently the migration and invasion of A549 cells under non-cytotoxic concentrations. Molecular data showed that the effect of andrographolide in A549 cells might be mediated via sustained inactivation of phosphatidylinositol 3-kinase (PI3K)/Akt signal involved in the up-regulation of matrix metalloproteinases (MMPs). Our results showed that andrographolide exerted an inhibitory effect on the activity and the mRNA and protein levels of MMP-7, but not MMP-2 or MMP-9. The andrographolide-inhibited MMP-7 expression or activity appeared to occur via activator protein-1 (AP-1) because of its DNA binding activity was suppressed by andrographolide. Additionally, the transfection of Akt over-expression vector (Akt1 cDNA) to A549 cells could result in an increase expression of MMP-7 concomitantly with a marked induction on cell invasion. These findings suggested that the inhibition on MMP-7 expression by andrographolide may be through suppression on PI3K/Akt/AP-1 signaling pathway, which in turn led to the reduced invasiveness of the cancer cells.