Arecoline, a major alkaloid of areca nut, inhibits p53, represses DNA repair, and triggers DNA damage response in human epithelial cells.
The International Agency for Research on Cancer declared that areca nut was carcinogenic to human. Areca nut is the main component of betel quid (BQ), which is commonly consumed in Asia. Epidemiological studies have shown that BQ chewing is a predominant risk factor for oral and pharyngeal cancers. It has been known that areca nut is genotoxic to human epithelial cells. However, the molecular and cellular mechanisms underlying areca nut-associated genotoxicity are not fully understood. Here we showed that arecoline, a major alkaloid of areca nut, might contribute to oral carcinogenesis through inhibiting p53 and DNA repair. We found, on the biological aspect, that arecoline could induce gamma-H2AX phosphorylation, a sensitive DNA damage marker, in KB, HEp-2, and 293 cells, suggesting that DNA damages were elicited by arecoline. This phenomenon was supported by the observations of arecoline-induced hyperphosphorylation of ATM, Nbs1, Chk1/2, p53, and Cdc25C, as well as G2/M cell cycle arrest, indicating that a cellular DNA damage response was activated. To explore the possible mechanism accounting for arecoline-elicited DNA damages, we found that arecoline could inhibit p53 by its expression and transactivation function. As a result, the expression of p53-regulated p21(WAF1) and the p53-activated DNA repair were repressed by arecoline. Finally, we showed that p53 mRNA transcripts were frequently down-regulated in BQ-associated oral cancer, suggesting that arecoline-mediated p53 inhibition might play a role in BQ-associated tumorigenesis.
Tsai
Yi-Shan
YS
Graduate Institute of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan.
Lee
Ka-Wo
KW
Huang
Jau-Ling
JL
Liu
Yu-Sen
YS
Juo
Suh-Hang Hank
SH
Kuo
Wen-Rei
WR
Chang
Jan-Gowth
JG
Lin
Chang-Shen
CS
Jong
Yuh-Jyh
YJ
D001114:Areca / Q000737:chemistry*; D001115:Arecoline / Q000633:toxicity*; D064007:Ataxia Telangiectasia Mutated Proteins; D015153:Blotting, Western; D002453:Cell Cycle / Q000187:drug effects; D018797:Cell Cycle Proteins / Q000378:metabolism; D045744:Cell Line, Tumor; D002478:Cells, Cultured; D004249:DNA Damage; D004260:DNA Repair / Q000187:drug effects*; D004847:Epithelial Cells / Q000187:drug effects / Q000378:metabolism*; D005434:Flow Cytometry; D019084:Fluorescent Antibody Technique, Indirect; D006657:Histones / Q000096:biosynthesis / Q000235:genetics; D006801:Humans; D007624:KB Cells; D009062:Mouth Neoplasms / Q000473:pathology; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D016159:Tumor Suppressor Protein p53 / Q000037:antagonists & inhibitors*
D018797:Cell Cycle Proteins; C468783:H2AX protein, human; D006657:Histones; D016159:Tumor Suppressor Protein p53; D001115:Arecoline; C576597:ATR protein, human; D064007:Ataxia Telangiectasia Mutated Proteins; D017346:Protein Serine-Threonine Kinases