FK506 Attenuates the MRP1-Mediated Chemoresistant Phenotype in Glioblastoma Stem-Like Cells

Int J Mol Sci. 2018 Sep 11;19(9):2697. doi: 10.3390/ijms19092697.


Poor response to current treatments for glioblastoma has been attributed to the presence of glioblastoma stem-like cells (GSCs). GSCs are able to expel antitumor drugs to the extracellular medium using the multidrug resistance-associated protein 1 (MRP1) transporter. Tacrolimus (FK506) has been identified as an MRP1 regulator in differentiated glioblastoma (GBM) cells (non-GSCs); however, the effect of FK506 on GSCs is currently unknown. The objective of the following research is to evaluate the effect of FK506 on the MRP1-related chemo-resistant phenotype of GSCs. For this, U87MG and C6 glioma cell lines were used to generate non-GSCs and GSCs. mRNA and MRP1-positive cells were evaluated by RT-qPCR and flow cytometry, respectively. A Carboxyfluorescein Diacetate (CFDA)-retention assay was performed to evaluate the MRP1 activity. Apoptosis and MTT assays were employed to evaluate the cytotoxic effects of FK506 plus Vincristine (MRP1 substrate). GSC-derived subcutaneous tumors were generated to evaluate the in vivo effect of FK506/Vincristine treatment. No differences in transcript levels and positive cells for MRP1 were observed in FK506-treated cells. Lesser cell viability, increased apoptosis, and CFDA-retention in the FK506/Vincristine-treated cells were observed. In vivo, the FK506/Vincristine treatment decreased the tumor size as well as ki67, Glial Fibrillary Acidic Protein (GFAP), and nestin expression. We conclude that FK506 confers a chemo-sensitive phenotype to MRP1-drug substrate in GSCs.

Keywords: ATP-binding cassette transporter; glioblastoma stem-like cells; multidrug resistance-associated protein 1; multiple drug resistance; tacrolimus.

MeSH terms

  • Animals
  • Antineoplastic Agents, Phytogenic / pharmacology
  • Antineoplastic Agents, Phytogenic / therapeutic use*
  • Apoptosis / drug effects
  • Brain Neoplasms / drug therapy*
  • Brain Neoplasms / genetics
  • Brain Neoplasms / metabolism
  • Brain Neoplasms / pathology
  • Cell Line, Tumor
  • Drug Resistance, Neoplasm / drug effects*
  • Glioblastoma / drug therapy*
  • Glioblastoma / genetics
  • Glioblastoma / metabolism
  • Glioblastoma / pathology
  • Humans
  • Male
  • Multidrug Resistance-Associated Proteins / genetics*
  • Multidrug Resistance-Associated Proteins / metabolism
  • Neoplastic Stem Cells / drug effects*
  • Neoplastic Stem Cells / metabolism
  • Neoplastic Stem Cells / pathology
  • Phenotype
  • Rats, Sprague-Dawley
  • Tacrolimus / pharmacology
  • Tacrolimus / therapeutic use*
  • Vincristine / pharmacology
  • Vincristine / therapeutic use*


  • Antineoplastic Agents, Phytogenic
  • Multidrug Resistance-Associated Proteins
  • Vincristine
  • Tacrolimus
  • multidrug resistance-associated protein 1