title: Elevated snail expression mediates tumor progression in areca quid chewing-associated oral squamous cell carcinoma via reactive oxygen species.
abstract: BACKGROUND
  Snail is an important transcription factor implicated in several tumor progression and can be induced by reactive oxygen species (ROS). Areca quid chewing is a major risk factor of oral squamous cell carcinoma (OSCC). Therefore, we hypothesize that the major areca nut alkaloid arecoline may induce Snail via ROS and involve in the pathogenesis of areca quid chewing-associated OSCC.
  
  
  RESULTS
  Thirty-six OSCC and ten normal oral epithelium specimens were examined by immunohistochemistry and analyzed by the clinico-pathological profiles. Cytotoxicity, 2', 7'-dichlorofluorescein diacetate assay, and western blot were used to investigate the effects of arecoline in human oral keratinocytes (HOKs) and oral epithelial cell line OECM-1 cells. In addition, antioxidants N-acetyl-L-cysteine (NAC), curcumin, and epigallocatechin-3 gallate (EGCG) were added to find the possible regulatory mechanisms. Initially, Snail expression was significantly higher in OSCC specimens (p<0.05). Elevated Snail expression was associated with lymph node metastasis (p = 0.031) and poor differentiation (p = 0.017). Arecoline enhanced the generation of intracellular ROS at the concentration higher than 40 µg/ml (p<0.05). Arecoline was also found to induced Snail expression in a dose- and time-dependent manner (p<0.05). Treatment with NAC, curcumin, and EGCG markedly inhibited arecoline induced Snail expression (p<0.05).
  
  
  CONCLUSIONS
  Our results suggest that Snail overexpression in areca quid chewing-associated OSCC is associated with tumors differentiation and lymph node metastasis. Arecoline-upregulated Snail expression may be mediated by ROS generation. In addition, arecoline induced Snail expression was downregulated by NAC, curcumin, and EGCG.
authors.affiliation: School of Public Health, Chung Shan Medical University, Taichung, Taiwan.
authors.forename: Shiuan-Shinn
authors.initials: SS
authors.lastname: Lee
authors.forename: Chung-Hung
authors.initials: CH
authors.lastname: Tsai
authors.forename: Cheng-Chia
authors.initials: CC
authors.lastname: Yu
authors.forename: Yu-Chao
authors.initials: YC
authors.lastname: Chang
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001114:Areca / Q000009:adverse effects*; D001115:Arecoline / Q000009:adverse effects / Q000494:pharmacology; D002294:Carcinoma, Squamous Cell / Q000139:chemically induced* / Q000473:pathology*; D002478:Cells, Cultured; D018450:Disease Progression; D005260:Female; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D006801:Humans; D008207:Lymphatic Metastasis; D008297:Male; D008409:Mastication / Q000502:physiology; D008875:Middle Aged; D009062:Mouth Neoplasms / Q000139:chemically induced* / Q000473:pathology*; D010936:Plant Extracts / Q000009:adverse effects*; D017382:Reactive Oxygen Species / Q000009:adverse effects; D000071250:Snail Family Transcription Factors; D014157:Transcription Factors / Q000235:genetics*; D015854:Up-Regulation / Q000187:drug effects
chemical_list: D010936:Plant Extracts; D017382:Reactive Oxygen Species; D000071250:Snail Family Transcription Factors; D014157:Transcription Factors; D001115:Arecoline