title: MicroRNA-21 contributes to the discrimination of chemoresistance in metastatic gastric cancer.
abstract: BACKGROUND
  Multidrug resistance in gastric cancer greatly impedes the efficacy of chemotherapy.
  
  
  OBJECTIVE
  To explore the efficacy of microRNA-21 (mir-21) in distinguishing metastatic gastric cancer (MGC) with chemoresistance.
  
  
  METHODS
  From April 2012 to May 2015, 92 MGC patients were enrolled. Cisplatin and fluorouracil-based systemic chemotherapy was given, and patients' characteristics and follow-up data were collected. In addition, miR-21 expression was determined in tumor tissue and plasma.
  
  
  RESULTS
  Sixty-seven patients responded to chemotherapy, and chemotherapy resistance was observed in 25 patients. miR-21 expression in tumor tissue and plasma was significantly elevated in the chemotherapy-resistant group (CRG) compared to the chemotherapy-sensitive group (CSG) (p< 0.001). miR-21 expression in tissue was associated with tumor differentiation (p= 0.042), and plasma miR-21 was correlated with gender (p= 0.016), tumor differentiation (p= 0.003), and number of metastatic sites (p< 0.001). Receiver operating characteristic (ROC) analysis indicated that miR-21 in tissue yielded an area under the ROC curve (AUC) of 0.830 (95%CI: 0.737-0.900, sensitivity: 88.0%, specificity: 68.7%) in distinguishing CRG from CSG; and plasma miR-21 yielded an AUC of 0.759 (95%CI: 0.658-0.842, sensitivity: 52.0%, specificity: 88.1%) in distinguishing CRG form CSG. Log-rank test and Cox proportional hazard regression analysis indicated that patients with higher miR-21 expression in tissue and plasma experienced shorter overall survival (P< 0.001).
  
  
  CONCLUSIONS
  miR-21 could serve as a potential biomarker to identify MGC with chemoresistance.
authors.affiliation: Department of Digestive System, Jinan Central Hospital Affiliated to Shandong University, Jinan 250013, Shandong, China.
authors.forename: Ming
authors.initials: M
authors.lastname: Qi
authors.affiliation: Transfusion Centre, Jinan Central Hospital Affiliated to Shandong University, Jinan 250013, Shandong, China.
authors.forename: Dongmei
authors.initials: D
authors.lastname: Liu
authors.affiliation: Department of Digestive System, Jinan Central Hospital Affiliated to Shandong University, Jinan 250013, Shandong, China.
authors.forename: Shuhong
authors.initials: S
authors.lastname: Zhang
mesh_terms: D000368:Aged; D014408:Biomarkers, Tumor / Q000235:genetics*; D018572:Disease-Free Survival; D019008:Drug Resistance, Neoplasm / Q000235:genetics*; D005260:Female; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D006801:Humans; D008297:Male; D035683:MicroRNAs / Q000235:genetics*; D008875:Middle Aged; D009362:Neoplasm Metastasis; D011379:Prognosis; D016016:Proportional Hazards Models; D013274:Stomach Neoplasms / Q000188:drug therapy* / Q000235:genetics / Q000473:pathology
chemical_list: D014408:Biomarkers, Tumor; C524940:MIRN21 microRNA, human; D035683:MicroRNAs
keywords: biomarker; gastric cancer; microRNA-21; survival analysis