MiR-200b and miR-15b regulate chemotherapy-induced epithelial-mesenchymal transition in human tongue cancer cells by targeting BMI1

Oncogene. 2012 Jan 26;31(4):432-45. doi: 10.1038/onc.2011.263. Epub 2011 Jul 4.

Abstract

Chemotherapy has been reported to induce epithelial-mesenchymal transition (EMT) in tumor cells, which is a critical step in the process of metastasis leading to cancer spreading and treatment failure. However, the underlying mechanisms of chemotherapy-induced EMT remain unclear, and the involvement of microRNAs (miRNA) in this process is poorly understood. To address these questions, we established stable chemotherapy-resistant tongue squamous cell carcinoma (TSCC) cell lines CAL27-res and SCC25-res by exposing the parental CAL27 and SCC25 lines to escalating concentrations of cisplatin for 6 months. CAL27-res and SCC25-res cells displayed mesenchymal features with enhanced invasiveness and motility. MiRNA microarray illustrated that miR-200b and miR-15b were the most significantly downregulated microRNAs in CAL27-res cells. Ectopic expression of miR-200b and miR-15b with miRNA mimics effectively reversed the phenotype of EMT in CAL27-res and SCC25-res cells, and sensitized them to chemotherapy, but inhibition of miR-200b and miR-15b in the sensitive lines with anti-sense oligonucleotides induced EMT and conferred chemoresistance. Retrieving the expression of B lymphoma Mo-MLV insertion region 1 homolog (BMI1), a target for miR-200b and miR-15b, in the presence of the miRNA mimics by transfecting CAL27-res cells with pcDNA3.1-BMI1-carrying mutated seed sequences of miR-200b or miR-15b at its 3'-UTR recapitulated chemotherapy-induced EMT. In vivo, enforced miR-200b or miR-15b expression suppressed metastasis of TSCC xenografts established by CAL27-res cells. Clinically, reduced miR-200b or miR-15b expression was associated with chemotherapeutic resistance in TSCCs and poor patient survival. Our data suggest that reduced expression of miR-200b and miR-15b underscores the mechanisms of chemotherapy-induced EMT in TSCC, and may serve as therapeutic targets to reverse chemotherapy resistance in tongue cancers.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Carcinoma, Squamous Cell / drug therapy
  • Carcinoma, Squamous Cell / pathology*
  • Cell Line, Tumor
  • Cisplatin / pharmacology
  • Drug Resistance, Neoplasm
  • Epithelial-Mesenchymal Transition / drug effects*
  • Humans
  • Mice
  • Mice, Inbred BALB C
  • MicroRNAs / physiology*
  • Nuclear Proteins / antagonists & inhibitors*
  • Nuclear Proteins / physiology
  • Polycomb Repressive Complex 1
  • Prognosis
  • Proto-Oncogene Proteins / antagonists & inhibitors*
  • Proto-Oncogene Proteins / physiology
  • RNA, Small Interfering / genetics
  • Repressor Proteins / antagonists & inhibitors*
  • Repressor Proteins / physiology
  • Tongue Neoplasms / drug therapy
  • Tongue Neoplasms / pathology*

Substances

  • BMI1 protein, human
  • MIRN15 microRNA, human
  • MIRN200 microRNA, human
  • MicroRNAs
  • Nuclear Proteins
  • Proto-Oncogene Proteins
  • RNA, Small Interfering
  • Repressor Proteins
  • Polycomb Repressive Complex 1
  • Cisplatin