title: MiR-141 Activates Nrf2-Dependent Antioxidant Pathway via Down-Regulating the Expression of Keap1 Conferring the Resistance of Hepatocellular Carcinoma Cells to 5-Fluorouracil.
abstract: BACKGROUND
  Hepatocellular carcinoma (HCC) is one of the most lethal malignancies worldwide. A major cause for the failure of cancer therapy is the development of chemoresistance. Although progress has been made in the study of the mechanisms underlying cancer cells resistance, little is known about the role of microRNAs (miRNAs) in cancer therapy resistance.
  
  
  RESULTS
  Fifteen miRNAs, including 6 up-regulated miRNAs (> 2.0-fold) and 9 down-regulated miRNAs (< 0.5-fold) were differentially expressed in 5-fluorouracil-resistant and their parental cell-lines (HepG2, HepG2/5-FU) by miRNA microarrays. Microarray results were confirmed by validating quantitative real-time polymerase chain reaction (qRT-PCR) analysis. Up-regulation of miR-141 expression resulted in a significant inhibition of 5-FU-mediated cytotoxicity and apoptosis in various hepatocellular carcinoma cells-lines. Mechanically, miR-141 promoted Kelch-like ECH-associated protein 1 (Keap1) mRNA degradation by directly targeting the Keap1 3'untranslated region (3'UTR). Treatment with miR-141 mimics in parental HepG2 cells, restored miR-141 expression and reduced Keap1 levels, thereby resulting in erythroid transcription factor NFE2-L2 (Nrf2) nuclear translocation, activation of Nrf2-dependent HO-1 gene transcription, and subsequent enhancement in 5-FU resistance. Conversely, restoring the expression of Keap1 partly recovered 5-FU sensitivity by counteracting miR-141-mediated 5-FU resistance.
  
  
  CONCLUSIONS
  Our study showed that miR-141 plays a key role in 5-FU resistance by down-regulating Keap1 expression, thereby reactivating the Nrf2-dependent antioxidant pathway, which may serve as a potential target for overcoming 5-FU resistance in hepatocellular carcinoma cells.
authors.affiliation: Department of Laboratory Medicine, The First Affiliated Hospital of Wenzhou Medical Uinversity, Wenzhou, China.
authors.forename: Liang
authors.initials: L
authors.lastname: Shi
authors.forename: Lili
authors.initials: L
authors.lastname: Wu
authors.forename: Zhanguo
authors.initials: Z
authors.lastname: Chen
authors.forename: Jianrong
authors.initials: J
authors.lastname: Yang
authors.forename: Xiaofei
authors.initials: X
authors.lastname: Chen
authors.forename: Fangyou
authors.initials: F
authors.lastname: Yu
authors.forename: Fang
authors.initials: F
authors.lastname: Zheng
authors.forename: Xiangyang
authors.initials: X
authors.lastname: Lin
mesh_terms: D020413:3' Untranslated Regions / Q000187:drug effects / Q000235:genetics; D000975:Antioxidants / Q000378:metabolism; D017209:Apoptosis / Q000187:drug effects / Q000235:genetics; D006528:Carcinoma, Hepatocellular / Q000188:drug therapy / Q000235:genetics*; D045744:Cell Line, Tumor; D015536:Down-Regulation / Q000187:drug effects / Q000235:genetics; D019008:Drug Resistance, Neoplasm / Q000235:genetics*; D005472:Fluorouracil / Q000494:pharmacology*; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects / Q000235:genetics; D051547:Heme Oxygenase-1 / Q000235:genetics; D056945:Hep G2 Cells; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins / Q000235:genetics*; D000072019:Kelch-Like ECH-Associated Protein 1; D008113:Liver Neoplasms / Q000188:drug therapy / Q000235:genetics*; D035683:MicroRNAs / Q000235:genetics*; D051267:NF-E2-Related Factor 2 / Q000235:genetics*; D015398:Signal Transduction / Q000187:drug effects / Q000235:genetics; D014158:Transcription, Genetic / Q000187:drug effects / Q000235:genetics; D015854:Up-Regulation / Q000187:drug effects / Q000235:genetics
chemical_list: D020413:3' Untranslated Regions; D000975:Antioxidants; D047908:Intracellular Signaling Peptides and Proteins; C431364:KEAP1 protein, human; D000072019:Kelch-Like ECH-Associated Protein 1; C533895:MIRN141 microRNA, human; D035683:MicroRNAs; D051267:NF-E2-Related Factor 2; C495635:NFE2L2 protein, human; C496541:HMOX1 protein, human; D051547:Heme Oxygenase-1; D005472:Fluorouracil