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PLoS Biol. 2014 Sep 9;12(9):e1001945. doi: 10.1371/journal.pbio.1001945. eCollection 2014 Sep.

De-differentiation confers multidrug resistance via noncanonical PERK-Nrf2 signaling.

Author information

1
Whitehead Institute for Biomedical Research, Cambridge, Massachusetts, United States of America.
2
Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America.
3
Whitehead Institute for Biomedical Research, Cambridge, Massachusetts, United States of America; Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America; Koch Institute for Integrative Cancer Research, Cambridge, Massachusetts, United States of America; Harvard Stem Cell Institute, Cambridge, Massachusetts, United States of America; Broad Institute, Cambridge, Massachusetts, United States of America.

Abstract

Malignant carcinomas that recur following therapy are typically de-differentiated and multidrug resistant (MDR). De-differentiated cancer cells acquire MDR by up-regulating reactive oxygen species (ROS)-scavenging enzymes and drug efflux pumps, but how these genes are up-regulated in response to de-differentiation is not known. Here, we examine this question by using global transcriptional profiling to identify ROS-induced genes that are already up-regulated in de-differentiated cells, even in the absence of oxidative damage. Using this approach, we found that the Nrf2 transcription factor, which is the master regulator of cellular responses to oxidative stress, is preactivated in de-differentiated cells. In de-differentiated cells, Nrf2 is not activated by oxidation but rather through a noncanonical mechanism involving its phosphorylation by the ER membrane kinase PERK. In contrast, differentiated cells require oxidative damage to activate Nrf2. Constitutive PERK-Nrf2 signaling protects de-differentiated cells from chemotherapy by reducing ROS levels and increasing drug efflux. These findings are validated in therapy-resistant basal breast cancer cell lines and animal models, where inhibition of the PERK-Nrf2 signaling axis reversed the MDR of de-differentiated cancer cells. Additionally, analysis of patient tumor datasets showed that a PERK pathway signature correlates strongly with chemotherapy resistance, tumor grade, and overall survival. Collectively, these results indicate that de-differentiated cells up-regulate MDR genes via PERK-Nrf2 signaling and suggest that targeting this pathway could sensitize drug-resistant cells to chemotherapy.

PMID:
25203443
PMCID:
PMC4159113
DOI:
10.1371/journal.pbio.1001945
[Indexed for MEDLINE]
Free PMC Article

Conflict of interest statement

The authors have declared that no competing interests exist.

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