Journal
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
Volume 112, Issue 17, Pages 5425-5430Publisher
NATL ACAD SCIENCES
DOI: 10.1073/pnas.1501555112
Keywords
Myc; MondoA; thioredoxin-interacting protein; glycolysis; triple-negative breast cancer
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Funding
- National Institutes of Health [5R01GM055668-15, 5R01DK084425-03]
- Huntsman Cancer Foundation
- Cancer Center Support Grant [P30 CA42014]
- China Scholarship Council [CSC-2011659013]
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Triple-negative breast cancers (TNBCs) are aggressive and lack targeted therapies. Understanding how nutrients are used in TNBCs may provide new targets for therapeutic intervention. We demonstrate that the transcription factor c-Myc drives glucose metabolism in TNBC cells but does so by a previously unappreciated mechanism that involves direct repression of thioredoxin-interacting protein (TXNIP). TXNIP is a potent negative regulator of glucose uptake, aerobic glycolysis, and glycolytic gene expression; thus its repression by c-Myc provides an alternate route to c-Myc-driven glucose metabolism. c-Myc reduces TXNIP gene expression by binding to an E-box-containing region in the TXNIP promoter, possibly competing with the related transcription factor MondoA. TXNIP suppression increases glucose uptake and drives a dependence on glycolysis. Ectopic TXNIP expression decreases glucose uptake, reduces cell proliferation, and increases apoptosis. Supporting the biological significance of the reciprocal relationship between c-Myc and TXNIP, a Myc(high)/TXNIPlow gene signature correlates with decreased overall survival and decreased metastasis-free survival in breast cancer. The correlation between the Myc(high)/TXNIPlow gene signature and poor clinical outcome is evident only in TNBC, not in other breast cancer subclasses. Mutation of TP53, which is a defining molecular feature of TNBC, enhances the correlation between the Myc(high)/TXNIPlow gene signature and death from breast cancer. Because Myc drives nutrient utilization and TXNIP restricts glucose availability, we propose that the Myc(high)/TXNIPlow gene signature coordinates nutrient utilization with nutrient availability. Further, our data suggest that loss of the p53 tumor suppressor cooperates with Myc(high)/TXNIPlow-driven metabolic dysregulation to drive the aggressive clinical behavior of TNBC.
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