The role of autophagy in the treatment of BRAF mutant colorectal carcinomas differs based on microsatellite instability status

PLoS One. 2018 Nov 14;13(11):e0207227. doi: 10.1371/journal.pone.0207227. eCollection 2018.

Abstract

Autophagy has been identified as a catabolic mechanism in cells but its' role in cancer remains controversial. Autophagy has been characterized either as tumor suppressor or inducer mechanism in many tumor types. Monoclonal antibodies against EGFR (cetuximab and panitumumab) represent a major step in the treatment of mCRC. Several studies propose that cetuximab and panitumumab trigger autophagy which reveals a potential resistance mechanism to these agents. The last years immunotherapy appears to be a novel promising strategy for the treatment of patients with solid tumors, including colorectal cancer. Checkpoint inhibitors, such as anti-PD1 (nivolumab and pembrolizumab) and anti-CTLA-4 (ipilimumab) antibodies have already been developed and applied in mCRC patients with MSI-H phenotype. The association between mtBRAF and autophagy or MSI status has already been characterized. In our study, we identify the autophagy initiation through anti-EGFR monoclonal antibodies and checkpoint inhibitors in colorectal carcinoma cell lines according to microsatellite status. The combination of autophagy inhibition, anti-EGFR antibodies and checkpoint inhibitors as well as autophagy targeting, MEK inhibition and anti-EGFR antibodies or checkpoint inhibitors appears to be the best treatment approach for microsatellite instability high and stable colorectal cancer cell lines, respectively. Both combinatorial approaches reduce cell viability through the induction of apoptotic cell death. The findings of this study point out the importance of different approach for the treatment of BRAF mutant metastatic colorectal cancers based on their microsatelite instability phenotype.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Antibodies, Monoclonal / therapeutic use
  • Antineoplastic Agents, Immunological / therapeutic use
  • Apoptosis / drug effects
  • Autophagy / genetics*
  • B7-H1 Antigen / antagonists & inhibitors
  • Caco-2 Cells
  • Cell Cycle Checkpoints / drug effects
  • Cell Line, Tumor
  • Colorectal Neoplasms / genetics*
  • Colorectal Neoplasms / pathology
  • Colorectal Neoplasms / therapy*
  • ErbB Receptors / antagonists & inhibitors
  • HCT116 Cells
  • Humans
  • Immunotherapy
  • Microsatellite Instability*
  • Mutation*
  • Protein Kinase Inhibitors / therapeutic use
  • Proto-Oncogene Proteins B-raf / genetics*

Substances

  • Antibodies, Monoclonal
  • Antineoplastic Agents, Immunological
  • B7-H1 Antigen
  • CD274 protein, human
  • Protein Kinase Inhibitors
  • EGFR protein, human
  • ErbB Receptors
  • BRAF protein, human
  • Proto-Oncogene Proteins B-raf

Grants and funding

Τhe research work was supported by the Hellenic Foundation for Research and Innovation (HFRI) and the General Secretariat for Research and Technology (GSRT), under the HFRI PhD Fellowship grant [GA. 665 (14482)] (to EK) and Institute of Molecular Medicine and Biomedical Research (to MVK). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.