miR-106b regulates the 5-fluorouracil resistance by targeting Zbtb7a in cholangiocarcinoma

BACKGROUND Cholangiocarcinoma (CCA) is highly resistant to chemo-therapy, including 5-fluorouracil (5-FU) treatment. MicroRNAs are endogenous and short non-coding RNAs that can regulate multiple genes expression. Many microRNAs have shown functional roles in the chemo-resistance of tumors. Here, we examined the relationship between microRNAs expression and the sensitivity of CCA cells to 5-FU. METHODS Microarray analysis was used to determine the aberrantly expressed microRNAs in two 5-FU resistant CCA cell lines, KKU-M139 and KKU-M214 cells. To determine the effect of candidate microRNAs on 5-FU sensitivity, expression of candidate was modified via either transfection of a microRNA mimic or transfection of an antagonist. Ontology-based programs were also used to investigate the potential targets of microRNAs that were confirmed to affect the 5-FU sensitivity of CCA cells. RESULTS The microRNA-106b (miR-106b) was significantly down-regulated in 5-FU resistant CCA cells. Instead, over-expression of miR-106b could re-sensitize resistant CCA cells to 5-FU through down-regulation of Zbtb7a. Moreover, decreased expression of miR-106b is related to poor prognosis in patients with CCA, suggesting its potential role as a new prognostic marker in CCA. CONCLUSION Our study demonstrates that miR-106b can reverse 5-FU resistance via Zbtb7a suppression, thus offer a novel and powerful strategy for CCA chemotherapy.