Role of miR-19b and its target mRNAs on 5-fluorouracil resistance in colon cancer cells

Despite the efforts in defining the molecular mechanisms for the drug resistance in colorectal cancers, little is known about the roles of microRNAs. With microarray containing 723 microRNAs, we examined effect of 5-fluorouracil (5-FU) on the microRNA expression. Respond to 5-FU, we identify two microRNAs, miR-19b and miR-21, that were differentially expressed in 5-FU resistant colon cancer cells derived from KM12C and DLD-1. DLD-1, DLD-1/R, KM12C, and KM12C/R cells were plated at 1 × 105 cells/well. After pre-culture, cells were treated with 60 uM of 5-FU for 72 h. This was the same condition as the analysis of cell cycle. RNAs were collected before (0 h) and after the treatment of 5-FU (72 h).