In Vitro anti-metastatic activity of enterolactone, a mammalian lignan derived from flax lignan, and down-regulation of matrix metalloproteinases in MCF-7 and MDA MB 321 cell lines
In Vitro anti-metastatic activity of enterolactone, a mammalian lignan derived from flax lignan, and down-regulation of matrix metalloproteinases in MCF-7 and MDA MB 321 cell lines
Year: 2012
Authors: Mali, A.V. Wagh, U.V. Hedge, M.V. Chandorkar, S.S. Surve, S.V. Patole, M.V.
Publication Name: Indian Journal of Cancer
Publication Details: Indian Journal of Cancer
Abstract:
Actin cytoskeleton is involved in actin-based cell adhesion, cell motility, and matrix metalloproteinases (MMPs) MMP2, MMP9, MMP11 and MMP14 are responsible for cell invasion in breast cancer metastasis. The dietary intake of lignan from flax seed gets converted to enterolactone (EL) and enterodiol in the human system. Here we show that the enterolactone has a very significant anti-metastatic activity as demonstrated by its ability to inhibit adhesion and invasion and migration in MCF-7 and MDA MB231 cell lines. Migration inhibition assay, actin-based cell motility assay along with reverse transcriptase polymerase chain reaction (RT-PCR) for MMP2, MMP9, MMP11 and MMP14 genes were performed in MCF-7 and MDA MB 231 cell lines. Enterolactone seems to inhibit actin-based cell motility as evidenced by confocal imaging and photo documentation of cell migration assay. The results are supported by the observation that the enterolactone in vitro significantly down-regulates the metastasis-related metalloproteinases MMP2, MMP9 and MMP14 gene expressions. No significant alteration in the MMP11 gene expression was found. Therefore we suggest that the anti-metastatic activity of EL is attributed to its ability to inhibit cell adhesion, cell invasion and cell motility. EL affects normal filopodia and lamellipodia structures, polymerization of actin filaments at their leading edges and thereby inhibits actin-based cell adhesion and cell motility. The process involves multiple force-generating mechanisms of actin filaments i.e. protrusion, traction, deadhesion and tail-retraction. By down-regulating the metastasis-related MMP2, MMP9 and MMP14 gene expressions, EL may be responsible for cell invasion step of metastasis. (Authors abstract)
Previous studies have shown that enterodiol (ED) and enterolactone (EL), metabolites of plant lignans found in flaxseed, and the cancer drug tamoxifen (TAM) alone or in combination, can influence the various steps of metastasis, including breast cancer cell adhesion, invasion and migration in to ER-human breast cancer cell lines MDA-MB-435 and MDA-MB-231. Also it has been shown that dietary flaxseed and/or its SDG can significantly inhibit spontaneous metastasis of human breast cancer in nude mice and experimental lung metastasis of murine melanoma. Flaxseed and its lignan and oil components can reduce rat mammary tumor growth at a late stage of carcinogenesis and the invasion to neighboring tissues. The present study demonstrates that the metabolic product of flax lignan, EL, can alter the metastasis process including cancer cell adhesion, invasion and migration. The study suggests cellular as well as molecular mechanisms by which flaxseed may inhibit experimental metastasis. It is now known that metastatic spreading occurs in about 50 percent of cases with apparently localized breast cancer, and that up to 30 percent of patients with LN negative disease will develop distant metastases within five years. Metastasis involves malignant cells breaking away from the primary tumor and attaching to and degrading proteins that make up the surrounding ECM, which separates the tumor from adjoining tissue. By degrading these proteins, cancer cells are able to break the ECM and escape and thus become metastatic. Reorganization of the actin cytoskeleton is the primary mechanism of cell migration. Adhesion is required for protrusion to be converted into movement along the substrate. In both filopodia and lamellipodia structures, protrusion of the membrane is tightly coupled to polymerization of actin filaments at the leading edge. The present study suggest that EL is capable of affecting normal filopodia and lamellipodia structures, polymerization of actin filaments at their leading edges and thereby actin based cell adhesion and cell motility involving multiple force generating mechanisms of actin filaments i.e. protrusion, traction, de adhesion and tail retraction. Tumor invasion plays a crucial role in metastasis and involves a number of important steps including adhesion of tumor cells to the BM; enzymatic digestion of the BM by proteolytic enzymes followed by migration through the ECM with the subsequent growth and proliferation of cells at a new site. The present study suggests that the EL is capable of decreasing the expression of MMP2, MMP9 and MMP14 genes significantly thereby possibly blocking the invasion of cancer cells through the BM.(Editors comments)
