Actin cytoskeleton reconstitution in MCF-7 breast cancer cells initiated by a native flax root extract

The intention of this systematic cell biological study was to analyze the effects of the phytoestrogen-rich, ethanolic flax root extract (Linum usitatissimum L.) on human MCF-7 estrogen receptor positive breast cancer cells in order to identify the main anti-tumor action by focusing on adhesion and migration related features. Cell impedance, initial adhesion capacity, cell migration ability, and actin cytoskeleton formation was determined by live cell monitoring, flow cytometry, scratch assay and confocal microscopy. Detailed expression analyses of adhesion- and actin-related proteins were performed by flow cytometry and western blotting, respectively. The effect on anchorage-independent growth of MCF-7 cells was analyzed by colony formation on soft agar. 50 µg/ml flax root extract reduced cell impedance (50%), initial adhesion capacity (18%), migration ability (72%) and colony formation (83%) in MCF-7 cells significantly. Increased stress fiber formation (9-fold higher filament number and a 12-fold elevation of the total filament length) was initiated by overexpression of profilin-1 and down regulation of arp-2, two important regulators of actin dynamics. In conclusion, the flax root extract exhibits anti-tumor potential for estrogen receptor positive breast cancer cells mainly by remodeling of the actin cytoskeleton, leading to significant reduction of migration and colony formation in vitro.

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