Aspirin effects on endometrial cancer cell growth

OBJECTIVE: To find whether aspirin (acetylsalicylic acid, ASA) inhibits the growth of endometrial cancer cells in vitro in a way similar to that in colorectal cancer cells and to investigate the mechanisms by which aspirin might lead to growth inhibition. METHODS: Ishikawa human endometrial tumor cells were grown in the presence of ASA (1-5 mM) for 96 hours. Controls were treated with vehicle (absolute ethanol). Cell proliferation was assessed by 3-(4,5-dimethylthiazol-2-yl) -2,5-diphenyltetrazolium bromide assay. Apoptosis was determined by terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling assay. Analysis of cell-cycle distribution and bcl-2 expression was assessed by flow cytometry. RESULTS: Acetylsalicylic acid induced a dose-dependent inhibition of Ishikawa cells in vitro. The percentage of growth inhibition was 21-88% at concentrations of 1-5 mM. It also induced apoptosis and reduced bcl-2 expression in Ishikawa cells in a dose-dependent manner. Control cells and cells treated with the lowest concentration of ASA exhibited 2% apoptosis and more than 60% of the population expressed bcl-2. Apoptosis levels increased as levels of ASA increased from 2 to 5 mM (7-58%) with a concommitant decrease in bcl-2 expression from 46% at 2 mM to 2% at 5 mM. Acetylsalicylic acid concentrations of 3 mM or greater induced a shift from the resting phase (G0/G1) to S phase of the cell cycle. CONCLUSION: Acetylsalicylic acid inhibited Ishikawa cell growth in vitro in a dose-dependent manner. Apoptosis is one of the mechanisms involved in the response, which can be mediated in part by downregulation of bcl-2.