title: Cancer stem cell phenotype is supported by secretory phospholipase A2 in human lung cancer cells.
abstract: BACKGROUND
  Lung cancer stem cells (CSCs) are a subpopulation of cells that drive growth, invasiveness, and resistance to therapy. Inflammatory eicosanoids are critical to maintain this malignant subpopulation. Secretory phospholipase A2 group IIa (sPLA2) is an important mediator of the growth and invasive potential of human lung cancer cells and regulates eicosanoid production. We hypothesized that sPLA2 plays a role in the maintenance of lung CSCs.
  
  
  METHODS
  Cancer stem cells from lung adenocarcinoma cell lines H125 and A549 were isolated using aldehyde dehydrogenase activity and flow cytometry. Protein and mRNA levels for sPLA2 were compared between sorted cells using Western blotting and quantitative reverse transcriptase-polymerase chain reaction techniques. Chemical inhibition of sPLA2 and short-hairpin RNA knockdown of sPLA2 were used to evaluate effects on tumorsphere formation.
  
  
  RESULTS
  Lung CSCs were isolated in 8.9%±4.1% (mean±SD) and 4.1%±1.6% of H125 and A549 cells respectively. Both sPLA2 protein and mRNA expression were significantly elevated in the CSC subpopulation of H125 (p=0.002) and A549 (p=0.005; n=4). Knockdown of sPLA2 significantly reduced tumorsphere formation in H125 (p=0.026) and A549 (p=0.001; n=3). Chemical inhibition of sPLA2 resulted in dose-dependent reduction in tumorsphere formation in H125 (p=0.003) and A549 (p=0.076; n=3).
  
  
  CONCLUSIONS
  Lung CSCs express higher levels of sPLA2 than the non-stem cell population. Our findings that viral knockdown and chemical inhibition of sPLA2 reduce tumorsphere formation in lung cancer cells demonstrate for the first time that sPLA2 plays an important role in CSCs. These findings suggest that sPLA2 may be an important therapeutic target for human lung cancer.
authors.affiliation: Division of Cardiothoracic Surgery, Department of Surgery, University of Colorado Denver, Anschutz Medical Campus, Aurora, Colorado.
authors.forename: Daine T
authors.initials: DT
authors.lastname: Bennett
authors.affiliation: Division of Cardiothoracic Surgery, Department of Surgery, University of Colorado Denver, Anschutz Medical Campus, Aurora, Colorado.
authors.forename: Xin-Sheng
authors.initials: XS
authors.lastname: Deng
authors.affiliation: Division of Cardiothoracic Surgery, Department of Surgery, University of Colorado Denver, Anschutz Medical Campus, Aurora, Colorado.
authors.forename: Jessica A
authors.initials: JA
authors.lastname: Yu
authors.affiliation: Division of Cardiothoracic Surgery, Department of Surgery, University of Colorado Denver, Anschutz Medical Campus, Aurora, Colorado.
authors.forename: Marshall T
authors.initials: MT
authors.lastname: Bell
authors.affiliation: Division of Cardiothoracic Surgery, Department of Surgery, University of Colorado Denver, Anschutz Medical Campus, Aurora, Colorado.
authors.forename: David C
authors.initials: DC
authors.lastname: Mauchley
authors.affiliation: Division of Cardiothoracic Surgery, Department of Surgery, University of Colorado Denver, Anschutz Medical Campus, Aurora, Colorado.
authors.forename: Xianzhong
authors.initials: X
authors.lastname: Meng
authors.affiliation: Division of Cardiothoracic Surgery, Department of Surgery, University of Colorado Denver, Anschutz Medical Campus, Aurora, Colorado.
authors.forename: T Brett
authors.initials: TB
authors.lastname: Reece
authors.affiliation: Division of Cardiothoracic Surgery, Department of Surgery, University of Colorado Denver, Anschutz Medical Campus, Aurora, Colorado.
authors.forename: David A
authors.initials: DA
authors.lastname: Fullerton
authors.affiliation: Division of Cardiothoracic Surgery, Department of Surgery, University of Colorado Denver, Anschutz Medical Campus, Aurora, Colorado. Electronic address: michael.weyant@ucdenver.edu.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Weyant
mesh_terms: D000230:Adenocarcinoma / Q000201:enzymology* / Q000235:genetics / Q000473:pathology; D045744:Cell Line, Tumor; D006801:Humans; D008175:Lung Neoplasms / Q000201:enzymology* / Q000235:genetics / Q000473:pathology; D014411:Neoplastic Stem Cells; D010641:Phenotype; D054497:Phospholipases A2, Secretory / Q000502:physiology*
chemical_list: D054497:Phospholipases A2, Secretory