A diterpenoid compound, excisanin A, inhibits the invasive behavior of breast cancer cells by modulating the integrin β1/FAK/PI3K/AKT/β-catenin signaling

Aim: Excisanin A, a diterpenoid compound purified from Isodon macrocalyxin D, has anti-cancer properties with little toxicity. In this study, the anti-invasive effects of excisanin A on breast Cancer cells and its molecular mechanism of action were investigated.

Main methods: MTT, wound healing, transwell chamber and cell adhesion assays were utilized to investigate the effects of excisanin A on MDA-MB-231 and SKBR3 cells. Western blotting, Real-Time PCR, RNA interference and luciferase reporter assays were employed to determine the molecular mechanism of action of excisanin A.

Key findings: Treating MDA-MB-231 and SKBR3 cells with 10-40μM excisanin A significantly inhibited cell migration and invasion and suppressed the mRNA and protein levels of matrix metalloproteinase-2 (MMP-2) and matrix metalloproteinase-9 (MMP-9) in a dose-dependent manner. Excisanin A efficiently abolished Integrin β1 expression and reduced the phosphorylation of the downstream kinases focal adhesion kinase (FAK) and Src. Excisanin A inhibited the phosphorylation of phosphoinositide 3-kinase (PI3K), Akt and glycogen synthase kinase 3 beta (GSK3β) and down-regulated β-catenin expression and the luciferase activity of the transcription factor LEF-1. Moreover, treating breast Cancer cells with siRNA targeting Integrin β1 inhibited cell invasion and migration.

Significance: These results demonstrated that excisanin A inhibited invasion by suppressing MMP-2 and MMP-9 expression; the Integrin β1/FAK/PI3K/Akt/β-catenin signaling pathway was involved in this process. Therefore, excisanin A might be a potential anti-metastatic chemotherapeutic agent for the treatment of breast Cancer.