Autophagy inhibitor facilitates gefitinib sensitivity in vitro and in vivo by activating mitochondrial apoptosis in triple negative breast cancer

PLoS One. 2017 May 22;12(5):e0177694. doi: 10.1371/journal.pone.0177694. eCollection 2017.

Abstract

Epidermal growth factor receptor (EGFR) is over-expressed in about 50% of Triple negative breast cancers (TNBCs), but EGFR inhibitors have not been effective in treating TNBC patients. Increasing evidence supports that autophagy was related to drug resistance at present. However, the role and the mechanism of autophagy to the treatment of TNBC remain unknown. In the current study, we investigated the effect of autophagy inhibitor to gefitinib (Ge) in TNBC cells in vitro and in nude mice vivo. Our study demonstrated that inhibition of autophagy by 3-Methyladenine or bafilomycin A1 improved Ge's sensitivity to MDA-MB-231 and MDA-MB-468 cells, as evidence from stronger inhibition of cell vitality and colony formation, higher level of G0/G1 arrest and DNA damage, and these effects were verified in nude mice vivo. Our data showed that the mitochondrial-dependent apoptosis pathway was activated in favor of promoting apoptosis in the therapy of Ge combined autophagy inhibitor, as the elevation of BAX/Bcl-2, Cytochrome C, and CASP3. These results demonstrated that targeting autophagy should be considered as an effective therapeutic strategy to enhance the sensitivity of EGFR inhibitors on TNBC.

MeSH terms

  • Adenine / administration & dosage
  • Adenine / analogs & derivatives*
  • Adenine / pharmacology
  • Animals
  • Autophagy / drug effects
  • Caspase 3 / metabolism
  • Cell Cycle Checkpoints / drug effects
  • Cell Line, Tumor
  • Cell Survival / drug effects
  • Cytochromes c / metabolism
  • Drug Synergism
  • Female
  • Gefitinib
  • Gene Expression Regulation, Neoplastic / drug effects
  • Humans
  • In Vitro Techniques
  • Macrolides / administration & dosage*
  • Macrolides / pharmacology
  • Mice
  • Mice, Nude
  • Mitochondria / drug effects*
  • Protein Kinase Inhibitors / administration & dosage*
  • Protein Kinase Inhibitors / pharmacology
  • Proto-Oncogene Proteins c-bcl-2 / metabolism
  • Quinazolines / administration & dosage*
  • Quinazolines / pharmacology
  • Triple Negative Breast Neoplasms / drug therapy*
  • Triple Negative Breast Neoplasms / metabolism
  • Xenograft Model Antitumor Assays

Substances

  • Macrolides
  • Protein Kinase Inhibitors
  • Proto-Oncogene Proteins c-bcl-2
  • Quinazolines
  • 3-methyladenine
  • bafilomycin A1
  • Cytochromes c
  • CASP3 protein, human
  • Caspase 3
  • Adenine
  • Gefitinib

Grants and funding

The reagents were supported by the Grants from the Natural Science Foundation of Shandong Province (ZR2015HM055). The URL is http://jihlx.sdstc.gov.cn/STDPMS/ZR/ProjectApplication/MyProjectList.aspx, and ZYY received the funding; Laboratory supplies was supported by the Grants from the key research and development plan of Shandong Province (2016GSF201185). The URL is http://jihlx.sdstc.gov.cn/STDPMS/GG/ProjectApplication/MyProjectList.aspx, and ZYY received the funding. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.