A Pharmacological Chaperone Molecule Induces Cancer Cell Death by Restoring Tertiary DNA Structures in Mutant hTERT Promoters

Hyun Jin Kang, Yunxi Cui, Holly Yin, Amy Scheid, William P.D. Hendricks, Jessica Schmidt, Aleksandar Sekulic, Deming Kong, Jeffrey M. Trent, Vijay Gokhale, Hanbin Mao, Laurence H. Hurley

Research output: Contribution to journalArticle

35 Scopus citations

Abstract

Activation of human telomerase reverse transcriptase (hTERT) is necessary for limitless replication in tumorigenesis. Whereas hTERT is transcriptionally silenced in normal cells, most tumor cells reactivate hTERT expression by alleviating transcriptional repression through diverse genetic and epigenetic mechanisms. Transcription-activating hTERT promoter mutations have been found to occur at high frequencies in multiple cancer types. These mutations have been shown to form new transcription factor binding sites that drive hTERT expression, but this model cannot fully account for differences in wild-type (WT) and mutant promoter activation and has not yet enabled a selective therapeutic strategy. Here, we demonstrate a novel mechanism by which promoter mutations activate hTERT transcription, which also sheds light on a unique therapeutic opportunity. Promoter mutations occur in a core promoter region that forms tertiary structures consisting of a pair of G-quadruplexes involved in transcriptional silencing. We show that promoter mutations exert a detrimental effect on the folding of one of these G-quadruplexes, resulting in a nonfunctional silencer element that alleviates transcriptional repression. We have also identified a small drug-like pharmacological chaperone (pharmacoperone) molecule, GTC365, that acts at an early step in the G-quadruplex folding pathway to redirect mutant promoter G-quadruplex misfolding, partially reinstate the correct folding pathway, and reduce hTERT activity through transcriptional repression. This transcription-mediated repression produces cancer cell death through multiple routes including both induction of apoptosis through inhibition of hTERT's role in regulating apoptosis-related proteins and induction of senescence by decreasing telomerase activity and telomere length. We demonstrate the selective therapeutic potential of this strategy in melanoma cells that overexpress hTERT.

Original languageEnglish (US)
Pages (from-to)13673-13692
Number of pages20
JournalJournal of the American Chemical Society
Volume138
Issue number41
DOIs
StatePublished - Oct 19 2016

ASJC Scopus subject areas

  • Catalysis
  • Chemistry(all)
  • Biochemistry
  • Colloid and Surface Chemistry

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    Kang, H. J., Cui, Y., Yin, H., Scheid, A., Hendricks, W. P. D., Schmidt, J., Sekulic, A., Kong, D., Trent, J. M., Gokhale, V., Mao, H., & Hurley, L. H. (2016). A Pharmacological Chaperone Molecule Induces Cancer Cell Death by Restoring Tertiary DNA Structures in Mutant hTERT Promoters. Journal of the American Chemical Society, 138(41), 13673-13692. https://doi.org/10.1021/jacs.6b07598