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Cancer Discov. 2019 May;9(5):662-679. doi: 10.1158/2159-8290.CD-17-1444. Epub 2019 Feb 18.

BCL6 Evolved to Enable Stress Tolerance in Vertebrates and Is Broadly Required by Cancer Cells to Adapt to Stress.

Author information

1
Division of Hematology and Oncology, Department of Medicine, Weill Cornell Medicine, New York, New York.
2
Department of Pharmacology, Weill Cornell Medicine, New York, New York.
3
Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada.
4
Department of Surgery, Weill Cornell Medicine, New York, New York.
5
MTA TTK Lendület Cancer Biomarker Research Group, Institute of Enzymology, Budapest, Hungary.
6
Semmelweis University 2nd Department of Pediatrics, Budapest, Hungary.
7
Princess Margaret Cancer Centre, Toronto, Ontario, Canada.
8
Emory Vaccine Center and Department of Pathology and Laboratory Medicine, Emory University, Atlanta, Georgia.
9
Division of Hematology and Oncology, Department of Medicine, Weill Cornell Medicine, New York, New York. amm2014@med.cornell.edu lec2010@med.cornell.edu.
#
Contributed equally

Abstract

Several lines of evidence link the canonical oncogene BCL6 to stress response. Here we demonstrate that BCL6 evolved in vertebrates as a component of the HSF1-driven stress response, which has been co-opted by the immune system to support germinal center formation and may have been decisive in the convergent evolution of humoral immunity in jawless and jawed vertebrates. We find that the highly conserved BTB corepressor binding site of BCL6 mediates stress adaptation across vertebrates. We demonstrate that pan-cancer cells hijack this stress tolerance mechanism to aberrantly express BCL6. Targeting the BCL6 BTB domain in cancer cells induces apoptosis and increases susceptibility to repeated doses of cytotoxic therapy. The chemosensitization effect upon BCL6 BTB inhibition is dependent on the derepression of TOX, implicating modulation of DNA repair as a downstream mechanism. Collectively, these data suggest a form of adaptive nononcogene addiction rooted in the natural selection of BCL6 during vertebrate evolution. SIGNIFICANCE: We demonstrate that HSF1 drives BCL6 expression to enable stress tolerance in vertebrates. We identify an HSF1-BCL6-TOX stress axis that is required by cancer cells to tolerate exposure to cytotoxic agents and points toward BCL6-targeted therapy as a way to more effectively kill a wide variety of solid tumors.This article is highlighted in the In This Issue feature, p. 565.

PMID:
30777872
PMCID:
PMC6497559
[Available on 2020-05-01]
DOI:
10.1158/2159-8290.CD-17-1444

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