title: Chronic pepsin exposure promotes anchorage-independent growth and migration of a hypopharyngeal squamous cell line.
abstract: OBJECTIVE
  (1) Investigate the role of reflux, specifically pepsin, in laryngopharyngeal carcinogenesis. (2) Evaluate effects of chronic pepsin exposure on cell migration, apoptosis, and colony-forming ability in hypopharyngeal cells.
  
  
  METHODS
  Translation research.
  
  
  METHODS
  Academic research laboratory.
  
  
  METHODS
  Human hypopharyngeal squamous carcinoma FaDu cells were chronically exposed to nonacidic pepsin (exposed for 24 hours, 4 times over 2 weeks at the following concentrations: 0.01 mg/mL, 0.1 mg/mL, or 1 mg/mL). Precise wounds were created in confluent cell plates, and rates of cell migration into wounds were quantified. Separately, cell viability of chronic pepsin-exposed FaDu cells acutely treated with paclitaxel was measured. Finally, a clonogenic assay was performed on these cells to measure effects of chronic pepsin exposure on colony-forming ability.
  
  
  RESULTS
  An increased rate of relative wound density was observed in chronic pepsin-treated (0.01 mg/mL, 0.1 mg/mL) cells compared with control (P < .001), suggesting greater rates of cell migration. Pepsin-treated (0.1 mg/mL) cells demonstrated on average greater cell viability compared with control after exposure to paclitaxel, suggesting possible apoptotic resistance; however, this was not statistically significant. Chronic pepsin exposure (0.1 mg/mL, 1 mg/mL) was associated with a dose-dependent increase in colony-forming ability relative to control (P < .001).
  
  
  CONCLUSIONS
  Hypopharyngeal squamous cell line chronically exposed to pepsin demonstrated increased cell migration and colony-forming ability relative to control cells. These experiments indicate that chronic pepsin exposure acts as a promoter of tumorigenesis and metastasis of airway epithelium, suggesting a role for pepsin in laryngopharyngeal carcinogenesis attributed to gastric reflux.
authors.affiliation: Department of Otolaryngology and Communication Sciences, Medical College of Wisconsin, Milwaukee, Wisconsin, USA.
authors.forename: Elizabeth A
authors.initials: EA
authors.lastname: Kelly
authors.forename: Tina L
authors.initials: TL
authors.lastname: Samuels
authors.forename: Nikki
authors.initials: N
authors.lastname: Johnston
mesh_terms: D017209:Apoptosis / Q000187:drug effects; D063646:Carcinogenesis / Q000187:drug effects*; D002294:Carcinoma, Squamous Cell / Q000473:pathology; D002465:Cell Movement / Q000187:drug effects / Q000502:physiology; D004305:Dose-Response Relationship, Drug; D005764:Gastroesophageal Reflux / Q000209:etiology / Q000473:pathology*; D006801:Humans; D007012:Hypopharyngeal Neoplasms / Q000209:etiology / Q000473:pathology*; D007013:Hypopharynx / Q000166:cytology / Q000187:drug effects; D010434:Pepsin A / Q000009:adverse effects / Q000494:pharmacology*; D012016:Reference Values; D012680:Sensitivity and Specificity; D014407:Tumor Cells, Cultured
chemical_list: D010434:Pepsin A
keywords: laryngeal cancer; laryngopharyngeal reflux; pepsin; reflux