Enterolactone Suppresses Proliferation, Migration and Metastasis of MDA-MB-231 Breast Cancer Cells Through Inhibition of uPA Induced Plasmin Activation and MMPs-Mediated ECM Remodeling

BACKGROUND: To enhance their own survival, tumor cells can manipulate their microenvironment through remodeling of the extra cellular matrix (ECM). The urokinase-type plasminogen activator (uPA) system catalyzes plasmin production which further mediates activation of matrix metalloproteinases (MMPs) and plays an important role in breast cancer invasion and metastasis through ECM remodeling. This provides a potential target for therapeutic intervention of breast cancer treatment. Enterolactone (EL) is derived from dietary flax lignans in the human body and is known to have anti-breast cancer activity. We here investigated molecular and cellular mechanisms of EL action on the uPA-plasmin-MMPs system. METHODS: MTT and trypan blue dye exclusion assays, anchorage-dependent clonogenic assays and wound healing assays were carried out to study effects on cell proliferation and viability, clonogenicity and migration capacity, respectively. Real-time PCR was employed to study gene expression and gelatin zymography was used to assess MMP-2 and MMP-9 activities. All data were statistically analysed and presented as mean ± SEM values. RESULTS: All the findings collectively demonstrated anticancer and antimetastatic potential of EL with antiproliferative, antimigratory and anticlonogenic cellular mechanisms. EL was found to exhibit multiple control of plasmin activation by down-regulating uPA expression and also up-regulating its natural inhibitor, PAI-1, at the mRNA level. Further, EL was found to down-regulate expression of MMP-2 and MMP-9 genes, and up-regulate TIMP-1 and TIMP-2; natural inhibitors of MMP-2 and MMP-9, respectively. This may be as a consequence of inhibition of plasmin activation, resulting in robust control over migration and invasion of breast cancer cells during metastasis. CONCLUSIONS: EL suppresses proliferation, migration and metastasis of MDA-MB-231 breast cancer cells by inhibiting induced ECM remodeling by the ‘uPA-plasmin-MMPs system’.