title: MiRNA-26a Contributes to the Acquisition of Malignant Behaviors of Doctaxel-Resistant Lung Adenocarcinoma Cells through Targeting EZH2.
abstract: OBJECTIVE
  Accumulating evidence revealed that microRNAs (miRNAs) have been demonstrated as critical molecules in tumor development and progression. MiR-26a, located in a fragile chromosomal region associated with various human cancer, has been reported to be involved in regulating various cellular process, such as proliferation, apoptosis and invasion through targeting multiple oncogene. Docetaxel-mediated chemotherapy has been applied in improving the survival and prognosis of patients with advanced lung adenocarcinoma (LAD). However, chemoresistance remains a major impediment to clinical application of this agent. It has been presented that decreased miR-26a expression lead to cisplatin resistance and promoted growth and migration in human lung cancer. Enhancer of zeste homolog 2 (EZH2) is the target of miR-26a. The present study aimed to investigate the function of miR-26a/EZH2 in the acquisition of malignant behaviors of LAD.
  
  
  METHODS
  MiR-26a and EZH2 expression levels in the dcetaxel-insensitive groups (n = 19) and the docetaxel-sensitive groups (n = 18) were assessed by qRT-PCR. Colony formation assay, flow cytometric analysis, wound healing assay, cell transwell assays and western blotting were performed to assess the effects of miR-26a on proliferation, apoptosis and epithelial-to-mesenchymal (EMT) phenotypes in docetaxel resistant LAD cells in vitro. Xenograft transplantation, immunohistochemistry, tunel assays and western blotting assays were employed to demonstrate the role of miR-26a in docetaxel resistant LAD cells in vivo. The expression level of EZH2 in docetaxel-resistant LAD cells and corresponding parental cells was detected by qRT-PCR and western blotting. The relationship between miR-26a and EZH2 was confirmed by luciferase reporter assay. And rescue assays were performed to further confirm that miRNA-26a contributes to the acquisition of malignant behaviors of docetaxel-resistant LAD cells through targeting EZH2.
  
  
  RESULTS
  MiR-26a was significantly down-regulated in the dcetaxel-insensitive groups (n = 19) compared with the docetaxel-sensitive groups (n = 18) assessed by qRT-PCR. MiR-26a decreased the proliferation, increased the apoptosis rate and reversed EMT to MET of docetaxel-resistant LAD cells both in vivo and vitro. EZH2 was confirmed as target of miR-26a. Rescue assays further verified that the function of miR-26a exerts in docetaxel-resistant LAD cells is through targeting EZH2.
  
  
  CONCLUSIONS
  Our data revealed that overexpression of miR-26a in docetaxel-resistant LAD cells could decrease the proliferation, increase the apoptosis rate and reverse EMT to MET of docetaxel-resistant LAD cells both in vivo and vitro and such function is partially exerted via downregulating EZH2. MiR-26a/EZH2 signal pathway makes contribute to the malignant phenotype of docetaxel-resistant of LAD cells which indicated that miR-26a exerts pivotal functions in the molecular etiology of chemoresistant lung adenocarcinoma.
authors.forename: Jing
authors.initials: J
authors.lastname: Chen
authors.forename: Yuejuan
authors.initials: Y
authors.lastname: Xu
authors.forename: Leilei
authors.initials: L
authors.lastname: Tao
authors.forename: Yan
authors.initials: Y
authors.lastname: Pan
authors.forename: Kai
authors.initials: K
authors.lastname: Zhang
authors.forename: Rui
authors.initials: R
authors.lastname: Wang
authors.forename: Long-Bang
authors.initials: LB
authors.lastname: Chen
authors.forename: Xiaoyuan
authors.initials: X
authors.lastname: Chu
mesh_terms: D020413:3' Untranslated Regions; D000230:Adenocarcinoma / Q000378:metabolism / Q000473:pathology*; D000077192:Adenocarcinoma of Lung; D000070416:Antagomirs / Q000378:metabolism; D017209:Apoptosis / Q000187:drug effects; D001483:Base Sequence; D014408:Biomarkers, Tumor / Q000235:genetics / Q000378:metabolism; D059447:Cell Cycle Checkpoints / Q000187:drug effects; D045744:Cell Line, Tumor; D002465:Cell Movement / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D000077143:Docetaxel; D019008:Drug Resistance, Neoplasm / Q000187:drug effects; D000071221:Enhancer of Zeste Homolog 2 Protein / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D058750:Epithelial-Mesenchymal Transition; D006801:Humans; D008175:Lung Neoplasms / Q000378:metabolism / Q000473:pathology*; D035683:MicroRNAs / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D009367:Neoplasm Staging; D034622:RNA Interference; D034741:RNA, Small Interfering / Q000378:metabolism; D016415:Sequence Alignment; D043823:Taxoids / Q000633:toxicity
chemical_list: D020413:3' Untranslated Regions; D000070416:Antagomirs; D014408:Biomarkers, Tumor; D035683:MicroRNAs; D034741:RNA, Small Interfering; D043823:Taxoids; D000077143:Docetaxel; C498409:EZH2 protein, human; D000071221:Enhancer of Zeste Homolog 2 Protein
keywords: Chemoresistance; Enhancer of zeste homolog 2; Epithelial-to-mesenchymal; Lung adenocarcinoma; microRNA-26a