title: Lung cancer-associated myofibroblasts reveal distinctive ultrastructure and function.
abstract: BACKGROUND
  Cancer-associated stromal cells interact with carcinoma cells and thus participate in tumor growth. Our aim was to characterize the ultrastructure and contractile properties of stromal cells in collagen gel cultured from lung cancer of various histological types and from tumor-free lung.
  
  
  METHODS
  Cells cultured from lung cancer (13 adenocarcinomas, six squamous cell carcinomas, one adenosquamous carcinoma, and one pleomorphic carcinoma) and tumor-free lung were analyzed by transmission electron microscopy and three-dimensional collagen gel contraction assays. The expression of α-smooth muscle actin (α-SMA), a recognized myofibroblast marker, was examined by immunoelectron microscopy from individual cells and by Western blotting from the whole cultured cell population.
  
  
  RESULTS
  According to their ultrastructure, the cell lines were composed of fibroblastic and myofibroblastic cells. In electron microscopy, cells of lung cancer exhibited more myofibroblastic features displaying higher amounts of actin belts (p = 0.057) and α-SMA labeling (p = 0.010) than cells from tumor-free lung. Myofibroblasts cultured from lung cancer of smokers expressed less α-SMA labeling (p = 0.013) than counterparts from nonsmokers. Western blotting revealed that cancer-associated fibroblasts expressed more α-SMA (p = 0.006) than cells from tumor-free lung, whereas cells from tumor-free central lung of smokers showed less α-SMA (p = 0.039) than counterparts from nonsmokers. Cells cultured from cancer contracted more in collagen gel than those from tumor-free lung. The contractile capacity in collagen gel correlated with the frequency of extracellular component of fibronexus by transmission electron microscopy.
  
  
  CONCLUSIONS
  Lung cancer-associated myofibroblasts are different both ultrastructurally and functionally when compared with cells cultured from tumor-free lung. Smoking altered myofibroblastic phenotype, regardless of their origin.
authors.affiliation: *Department of Internal Medicine/Respiratory Research Unit, Institute of Clinical Medicine, University of Oulu, Oulu, Finland; †Department of Medicine, Respiratory Research Unit and Medical Research Center Oulu, Oulu University Hospital, Oulu, Finland; ‡Department of Anatomy and Cell Biology, Institute of Biomedicine, §Biocenter Oulu, and ‖Department of Pathology, Institute of Diagnostics, University of Oulu, Oulu, Finland; ¶Department of Pathology, Oulu University Hospital, Oulu, Finland; #Department of Medicine, Division of Respiratory Medicine, Karolinska Institutet, Karolinska University Hospital Solna, Stockholm, Sweden; **Unit of Medicine and Clinical Research, Pulmonary Division, University of Eastern Finland, Kuopio, Finland; and ††Center for Medicine and Clinical Research, Division of Respiratory Medicine, Kuopio University Hospital, Kuopio, Finland.
authors.forename: Henna M
authors.initials: HM
authors.lastname: Karvonen
authors.forename: Siri T
authors.initials: ST
authors.lastname: Lehtonen
authors.forename: Raija T
authors.initials: RT
authors.lastname: Sormunen
authors.forename: Elisa
authors.initials: E
authors.lastname: Lappi-Blanco
authors.forename: C Magnus
authors.initials: CM
authors.lastname: Sköld
authors.forename: Riitta L
authors.initials: RL
authors.lastname: Kaarteenaho
mesh_terms: D000199:Actins / Q000032:analysis; D000230:Adenocarcinoma / Q000503:physiopathology / Q000648:ultrastructure*; D022005:Adherens Junctions / Q000648:ultrastructure; D000368:Aged; D000369:Aged, 80 and over; D018196:Carcinoma, Adenosquamous / Q000503:physiopathology / Q000648:ultrastructure*; D002294:Carcinoma, Squamous Cell / Q000503:physiopathology / Q000648:ultrastructure*; D018870:Endoplasmic Reticulum, Rough / Q000648:ultrastructure; D005109:Extracellular Matrix / Q000648:ultrastructure; D005260:Female; D006801:Humans; D008168:Lung / Q000737:chemistry / Q000502:physiology / Q000648:ultrastructure; D008175:Lung Neoplasms / Q000737:chemistry / Q000503:physiopathology / Q000648:ultrastructure*; D008297:Male; D046529:Microscopy, Electron, Transmission; D008875:Middle Aged; D058628:Myofibroblasts / Q000737:chemistry / Q000502:physiology / Q000648:ultrastructure*; D012907:Smoking; D014407:Tumor Cells, Cultured
chemical_list: C541116:ACTA2 protein, human; D000199:Actins