Figure 1.

Colon cancer cells show differential responses to 5-FU treatment. (a and b), RKO, HCT116, FET and GEO cells were treated with increasing concentrations of 5-FU for 72 h. MTT assays (a) and DNA fragmentation assays (b) showed different sensitivity of those cells to 5-FU treatment. (c) Western blot analysis showed that cleaved PARP was higher in RKO and HCT116 cells than in FET and GEO cells after 10 μg/ml of 5-FU treatment for 72 h. (d) Determined by real time Q-PCR analysis, miR-587 expression in RKO and HCT116 cells, which are relatively sensitive to 5-FU-induced apoptosis, is significantly reduced after exposure to 8 μg/ml 5-FU for 72 h, whereas its expression remained unchanged in relatively resistant FET and GEO cells. (e) RT-PCR analysis showed 5-FU inhibited the expression of pri-miR-587 and pre-miR-587. (f) Quantitative real-time PCR analysis showed 5-FU inhibited miR-587 expression in wild-type (WT) p53 but not p53^−/− HCT116 cells. The data are presented as the mean±S.D. of triplicate experiments. *P<0.05, ***P<0.001