Amelioration of cancer stem cells in macrophage colony stimulating factor-expressing U87MG-human glioblastoma upon 5-fluorouracil therapy

PLoS One. 2013 Dec 31;8(12):e83877. doi: 10.1371/journal.pone.0083877. eCollection 2013.

Abstract

Macrophage colony stimulating factor (MCSF) regulates growth, proliferation and differentiation of haematopoietic cell lineages. Many cancers are known to secrete high level of MCSF, which recruit macrophages into the tumour micro-environment, supporting tumour growth. Herein, we report the cloning of MCSF and subsequent generation of U87MG expressing MCSF stable cell line (U87-MCSF). Cytotoxicity of anti-cancer drug 5-fluorouracil (5-FU) was evaluated on both U87MG and U87-MCSF cells. Interestingly, the proliferation of U87-MCSF cells was less (p<0.001) than that of U87MG cells alone, after treatment with 5-FU. Significant decrease in expression levels of cyclin E and A2 quantified by real time PCR analysis corroborated the reduced proliferation of 5-FU treated U87-MCSF cells. However, JC-1 staining did not reveal any apoptosis upon 5-FU treatment. Notch-1 upregulation induced a possible epithelial-mesenchymal transition in U87-MCSF cells, which accounted for an increase in the proportion of CD24(high)/CD44(less) cancer stem cells in U87-MCSF cells after 5-FU treatment. The elevated resistance of U87-MCSF cells towards 5-FU was due to the increase in the expressions (10.2 and 6 fold) of ABCB1 and mdm2, respectively. Furthermore, increase in expressions of ABCG1, mdm2 and CD24 was also observed in U87MG cells after prolonged incubation with 5-FU. Our studies provided mechanistic insights into drug resistance of U87MG cells and also described the pivotal role played by MCSF in augmenting the resistance of U87MG cells to 5-FU.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Antimetabolites, Antineoplastic / pharmacology*
  • Apoptosis / drug effects
  • Blotting, Western
  • Cell Cycle / drug effects
  • Cell Proliferation / drug effects
  • Drug Resistance, Neoplasm*
  • Flow Cytometry
  • Fluorouracil / pharmacology*
  • Glioblastoma / drug therapy*
  • Glioblastoma / metabolism
  • Glioblastoma / pathology
  • Humans
  • Macrophage Colony-Stimulating Factor / genetics
  • Macrophage Colony-Stimulating Factor / metabolism*
  • Neoplastic Stem Cells / drug effects*
  • Neoplastic Stem Cells / metabolism
  • Neoplastic Stem Cells / pathology
  • RNA, Messenger / genetics
  • Real-Time Polymerase Chain Reaction
  • Reverse Transcriptase Polymerase Chain Reaction
  • Tumor Cells, Cultured

Substances

  • Antimetabolites, Antineoplastic
  • RNA, Messenger
  • Macrophage Colony-Stimulating Factor
  • Fluorouracil

Grant support

Funding provided by Department of Biotechnology No. BT/49/NE/TBP/2010 and BT/01/NE/PS/08. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.