title: miR-506 enhances the sensitivity of human colorectal cancer cells to oxaliplatin by suppressing MDR1/P-gp expression.
abstract: OBJECTIVE
  Chemoresistance development represents a major obstacle to the successful treatment of colorectal cancer (CRC). The aim of this study was to elucidate the mechanism by which miR-506 reverses oxaliplatin chemoresistance in CRC.
  
  
  METHODS
  In this study, miR-506 levels were measured in 74 patients with colon cancer via quantitative real-time polymerase chain reaction (qRT-PCR) and in situ hybridization (ISH). We subsequently analysed the relationship between miR-506 expression and CRC patient survival via the Kaplan-Meier method. MTT assay demonstrated the fractional survival rates and cell viability of HCT116-OxR, HCT116-OxR-miR-Ctrl and HCT116-OxR-miR-506 cells treated with oxaliplatin at different concentrations. Cell proliferation and apoptosis were assessed via flow cytometry (FCM) analysis and apoptosis assay. MDR1 mRNA expression and P-gp protein expression were assessed via qRT-PCR and Western blotting (WB) respectively. Immunofluorescence (IF) staining demonstrated P-gp expression in HCT116-OxR and HCT116-OxR-miR-506 cells. qRT-PCR and WB were used to detect Wnt/β-catenin pathway activity after miR-506 overexpression.
  
  
  RESULTS
  In the present study, in ISH and qRT-PCR results demonstrated that miR-506 is weakly expressed in chemoresistant CRC tissues. The low miR-506 expression group exhibited lower 5-year OS and lower 5-year RFS than the high miR-506 expression group. miR-506 overexpression inhibited cell growth and increased oxaliplatin-induced cell apoptosis in HCT116-OxR cells, as shown via FCM and apoptosis assay. We subsequently noted low MDR1/P-gp expression in HCT116-OxR-miR-506 cells via qRT-PCR, WB and IF. Lastly, we demonstrated low MDR1/P-gp expression in HCT116-OxR-miR-506 cells via inhibition of the Wnt/β-catenin by WB, MTT and FCM analysis.
  
  
  CONCLUSIONS
  Taken together, the findings of our study demonstrate that miR-506 overexpression in HCT116-OxR cells enhances oxaliplatin sensitivity by inhibiting MDR1/P-gp expression via down-regulation of the Wnt/β-catenin pathway and thus provide a rationale for the development of miRNA-based strategies to reverse oxaliplatin resistance in CRC cells.
authors.affiliation: Department of Oncological Surgery, Affiliated Hospital of Xuzhou Medical University, Xuzhou, China.|Department of General Surgery, Wuhan Third Hospital, Wuhan, China.
authors.forename: Hui
authors.identifier: http://orcid.org/0000-0002-3757-0352
authors.initials: H
authors.lastname: Zhou
authors.affiliation: Department of Oncological Surgery, Affiliated Hospital of Xuzhou Medical University, Xuzhou, China.|Department of Gastrointestinal Surgery, Third Xiangya Hospital, Central South University, Changsha, China.
authors.forename: Changwei
authors.initials: C
authors.lastname: Lin
authors.affiliation: Department of Oncological Surgery, Affiliated Hospital of Xuzhou Medical University, Xuzhou, China.
authors.forename: Yi
authors.identifier: http://orcid.org/0000-0003-4691-9162
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Department of Oncological Surgery, Affiliated Hospital of Xuzhou Medical University, Xuzhou, China.
authors.forename: Xiuzhong
authors.initials: X
authors.lastname: Zhang
authors.affiliation: Department of Oncological Surgery, Affiliated Hospital of Xuzhou Medical University, Xuzhou, China.
authors.forename: Chong
authors.initials: C
authors.lastname: Zhang
authors.affiliation: Department of Oncological Surgery, Affiliated Hospital of Xuzhou Medical University, Xuzhou, China.
authors.forename: Pengbo
authors.initials: P
authors.lastname: Zhang
authors.affiliation: Department of General Surgery, Wuhan Third Hospital, Wuhan, China.
authors.forename: Xingwang
authors.initials: X
authors.lastname: Xie
authors.affiliation: Department of Oncological Surgery, Affiliated Hospital of Xuzhou Medical University, Xuzhou, China.
authors.forename: Zeqiang
authors.initials: Z
authors.lastname: Ren
mesh_terms: D018435:ATP Binding Cassette Transporter, Subfamily B / Q000096:biosynthesis / Q000172:deficiency / Q000235:genetics; D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000096:biosynthesis / Q000172:deficiency* / Q000235:genetics; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000970:Antineoplastic Agents / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects; D002453:Cell Cycle / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D002986:Clinical Trials as Topic; D015179:Colorectal Neoplasms / Q000175:diagnosis / Q000188:drug therapy* / Q000235:genetics*; D015536:Down-Regulation / Q000187:drug effects; D019008:Drug Resistance, Neoplasm / Q000187:drug effects; D004354:Drug Screening Assays, Antitumor; D005260:Female; D006801:Humans; D008297:Male; D035683:MicroRNAs / Q000235:genetics* / Q000378:metabolism; D008875:Middle Aged; D009944:Organoplatinum Compounds / Q000494:pharmacology*; D000077150:Oxaliplatin; D014407:Tumor Cells, Cultured; D060449:Wnt Signaling Pathway / Q000187:drug effects; D051176:beta Catenin / Q000037:antagonists & inhibitors / Q000378:metabolism
chemical_list: C513055:ABCB1 protein, human; D018435:ATP Binding Cassette Transporter, Subfamily B; D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D000970:Antineoplastic Agents; C561508:MIRN506 microRNA, human; D035683:MicroRNAs; D009944:Organoplatinum Compounds; D051176:beta Catenin; D000077150:Oxaliplatin
keywords: MDR1/P-gp; chemoresistance; colorectal cancer; miR-506