title: Enterolactone alters FAK-Src signaling and suppresses migration and invasion of lung cancer cell lines.
abstract: BACKGROUND
  Systemic toxicity of chemotherapeutic agents and the challenges associated with targeting metastatic tumors are limiting factors for current lung cancer therapeutic approaches. To address these issues, plant-derived bioactive components have been investigated for their anti-cancer properties because many of these agents are non-toxic to healthy tissues. Enterolactone (EL) is a flaxseed-derived mammalian lignan that has demonstrated anti-migratory properties for various cancers, but EL has not been investigated in the context of lung cancer, and its anticancer mechanisms are ill-defined. We hypothesized that EL could inhibit lung cancer cell motility by affecting the FAK-Src signaling pathway.
  
  
  METHODS
  Non-toxic concentrations of EL were identified for A549 and H460 human lung cancer cells by conducting 3-(4, 5-Dimethylthiazol-2-yl)-2, 5-Dephenyltetrazolium Bromide (MTT) assays. The anti-migratory and anti-invasive potential of EL for lung cancer cell lines was determined by scratch wound healing and Matrigel® invasion assays. Changes in filamentous actin (F-actin) fiber density and length in EL-treated cells were determined using phalloidin-conjugated rhodamine dye and fluorescent microscopy. Vinculin expression in focal adhesions upon EL treatment was determined by immunocytochemistry. Gene and protein expression levels of FAK-Src signaling molecules in EL-treated lung cancer cells were determined using PCR arrays, qRT-PCR, and western blotting.
  
  
  RESULTS
  Non-toxic concentrations of EL inhibited lung cancer cell migration and invasion in a concentration- and time-dependent manner. EL treatment reduced the density and number of F-actin fibers in lung cancer cell lines, and reduced the number and size of focal adhesions. EL decreased phosphorylation of FAK and its downstream targets, Src, paxillin, and decreased mRNA expression of cell motility-related genes, RhoA, Rac1, and Cdc42 in lung cancer cells.
  
  
  CONCLUSIONS
  Our data suggest that EL suppresses lung cancer cell motility and invasion by altering FAK activity and subsequent activation of downstream proteins needed for focal adhesion formation and cytoskeletal rearrangement. Therefore, administration of EL may serve as a safe and complementary approach for inhibiting lung tumor cell motility, invasion, and metastasis.
authors.affiliation: Department of Biological Sciences, North Dakota State University, Fargo, ND, 51808, USA.
authors.forename: Shireen
authors.initials: S
authors.lastname: Chikara
authors.affiliation: Department of Biological Sciences, North Dakota State University, Fargo, ND, 51808, USA.
authors.forename: Kaitlin
authors.initials: K
authors.lastname: Lindsey
authors.affiliation: Department of Biological Sciences, North Dakota State University, Fargo, ND, 51808, USA.|Department of Animal Sciences, North Dakota State University, Fargo, ND 51808, USA.
authors.forename: Pawel
authors.initials: P
authors.lastname: Borowicz
authors.affiliation: Department of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA.
authors.forename: Melpo
authors.initials: M
authors.lastname: Christofidou-Solomidou
authors.affiliation: Department of Biological Sciences, North Dakota State University, Fargo, ND, 51808, USA. katie.reindl@ndsu.edu.
authors.forename: Katie M
authors.initials: KM
authors.lastname: Reindl
mesh_terms: D015107:4-Butyrolactone / Q000031:analogs & derivatives* / Q000494:pharmacology; D002448:Cell Adhesion / Q000187:drug effects; D045744:Cell Line, Tumor; D002465:Cell Movement / Q000187:drug effects*; D003599:Cytoskeleton / Q000378:metabolism; D019597:Flax / Q000737:chemistry*; D051417:Focal Adhesion Kinase 1 / Q000235:genetics / Q000378:metabolism; D006801:Humans; D017705:Lignans / Q000494:pharmacology*; D008175:Lung Neoplasms / Q000188:drug therapy / Q000235:genetics / Q000378:metabolism* / Q000503:physiopathology*; D010766:Phosphorylation / Q000187:drug effects; D010936:Plant Extracts / Q000494:pharmacology*; D015398:Signal Transduction / Q000187:drug effects*; D019061:src-Family Kinases / Q000235:genetics / Q000378:metabolism
chemical_list: D017705:Lignans; D010936:Plant Extracts; D051417:Focal Adhesion Kinase 1; C496050:PTK2 protein, human; D019061:src-Family Kinases; D015107:4-Butyrolactone; C029497:2,3-bis(3'-hydroxybenzyl)butyrolactone
keywords: Cell motility; Enterolactone; F-actin; Flaxseed; Focal adhesion; Lung cancer cells; Rho GTPases