Areca nut extract induced oxidative stress and upregulated hypoxia inducing factor leading to autophagy in oral cancer cells.
Areca (betel) chewing was tightly linked to oral tumorigenesis in Asians. Areca nut was a recently confirmed group I carcinogen and a popular addictive substance used by Asians. Meanwhile, the pathogenetic impact of areca on oral epithelial cells was still unclear. This study investigated the association between the induction of autophagy by areca nut extract (ANE) and the molecular regulation underlying this induction in oral cancer cells. Oral cancer cells were treated with ANE to incite the signaling changes underlying phenotypic alterations. The NFkappaB activation and reactive oxygen species (ROS) genesis were induced by ANE and the NFkappaB activation could be the basis of the ROS genesis. Furthermore, p38 activation and upregulation of MKP-1 phosphatase occurred following ANE treatment. These effects can be inhibited by ROS blockers. ANE treatment induced autophagy among oral cancer cells, which was characterized by LC3-II accumulation, genesis of autophagosomes and the appearance of EGFP-LC3 puncta. This induction was mediated through the activation of p38, MKP-1 and HIF-1alpha. Knockdown of ANE-modulated HIF-1alpha expression reduced autophagy. Blockage of ANE-induced autophagy increased the proportion of oral cancer cells undergoing apoptotic death. This study identified for the first time that ANE modulates a signaling cascade that induces HIF-1alpha expression in oral cancer cells. The eventual induction of autophagy was beneficial to cell survival from ANE-induced apoptosis.
School of Dentistry, National Yang-Ming University, Taipei, Taiwan.
Hsuan-Hsuan
HH
Lu
Shou-Yen
SY
Kao
Tsung-Yun
TY
Liu
Shou-Tien
ST
Liu
Wei-Pang
WP
Huang
Kuo-Wei
KW
Chang
Shu-Chun
SC
Lin
D017209:Apoptosis / Q000187:drug effects; D001114:Areca / Q000737:chemistry*; D001343:Autophagy / Q000187:drug effects*; D045744:Cell Line, Tumor; D054638:Dual Specificity Phosphatase 1 / Q000378:metabolism; D004789:Enzyme Activation / Q000187:drug effects; D049452:Green Fluorescent Proteins / Q000378:metabolism; D006801:Humans; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000378:metabolism*; D008869:Microtubule-Associated Proteins / Q000378:metabolism; D009062:Mouth Neoplasms / Q000201:enzymology / Q000473:pathology*; D016328:NF-kappa B / Q000378:metabolism; D009754:Nuts / Q000737:chemistry; D018384:Oxidative Stress / Q000187:drug effects*; D010588:Phagosomes / Q000187:drug effects / Q000378:metabolism / Q000648:ultrastructure; D008517:Phytotherapy; D010936:Plant Extracts / Q000494:pharmacology*; D017382:Reactive Oxygen Species / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D015854:Up-Regulation / Q000187:drug effects*; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism
C497442:HIF1A protein, human; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; C477012:MAP1LC3A protein, human; D008869:Microtubule-Associated Proteins; D016328:NF-kappa B; D010936:Plant Extracts; D017382:Reactive Oxygen Species; C485184:enhanced green fluorescent protein; D049452:Green Fluorescent Proteins; D048051:p38 Mitogen-Activated Protein Kinases; C517019:DUSP1 protein, human; D054638:Dual Specificity Phosphatase 1