title: Mechanisms underlying aspirin-mediated growth inhibition and apoptosis induction of cyclooxygenase-2 negative colon cancer cell line SW480.
abstract: OBJECTIVE
  To investigate the effects of aspirin (acetylsalicylic acid) on proliferation and apoptosis of colorectal cancer cell line SW480 and its mechanism.
  
  
  METHODS
  Cyclooxygenase (COX)-2 negative colorectal cancer cell line SW480 was treated with aspirin at concentrations of 2.5 mmol/L, 5.0 mmol/L, 10.0 mmol/L for different periods in vitro. Anti-proliferation effect of aspirin on SW480 was detected by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Cell cycle and apoptosis were observed by flow cytometry (FCM). Transmission electron microscope (TEM) was used for morphological study. Apoptosis-associated genes were detected by immunohistochemical staining and Western blotting.
  
  
  RESULTS
  Aspirin inhibited SW480 proliferation and induced apoptosis in a dose- and time-dependent manner. Treatment with different concentrations of aspirin significantly increased the proportions of cells at the G(0)/G(1)phase and decreased the proportions of cells at the S- and G(2)/M phases in a concentration-dependent manner. Aspirin not only induced apoptosis but also caused cell necrosis at a high concentration as well. After treatment with aspirin, SW480 cells displayed typically morphological features of apoptosis and necrosis under TEM, and increased the Bcl-2 expression in cells, but the expression of Bax was down regulated.
  
  
  CONCLUSIONS
  Aspirin inhibits proliferation and induces apoptosis of SW480 cells. Its anti-tumor mechanism may arrest cell cycle and shift Bax/Bcl-2 balance in cells.
authors.affiliation: Department of Gastroenterology, First Affiliated Hospital, Guangxi Medical University, No. 6 Shuangyong Rd, Nanning 530021, Guangxi Zhuang Autonomous Region, China.
authors.forename: Ming-Yu
authors.initials: MY
authors.lastname: Lai
authors.forename: Jie-An
authors.initials: JA
authors.lastname: Huang
authors.forename: Zhi-Hai
authors.initials: ZH
authors.lastname: Liang
authors.forename: Hai-Xing
authors.initials: HX
authors.lastname: Jiang
authors.forename: Guo-Du
authors.initials: GD
authors.lastname: Tang
mesh_terms: D017209:Apoptosis / Q000187:drug effects*; D001241:Aspirin / Q000494:pharmacology*; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D003110:Colonic Neoplasms / Q000188:drug therapy* / Q000201:enzymology / Q000473:pathology; D051546:Cyclooxygenase 2 / Q000032:analysis*; D016193:G1 Phase / Q000187:drug effects; D006801:Humans; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000032:analysis; D016192:Resting Phase, Cell Cycle / Q000187:drug effects; D051028:bcl-2-Associated X Protein / Q000032:analysis
chemical_list: D019253:Proto-Oncogene Proteins c-bcl-2; D051028:bcl-2-Associated X Protein; D051546:Cyclooxygenase 2; C496540:PTGS2 protein, human; D001241:Aspirin