title: A Pharmacological Chaperone Molecule Induces Cancer Cell Death by Restoring Tertiary DNA Structures in Mutant hTERT Promoters.
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.
authors.affiliation: University of Arizona , College of Pharmacy, 1703 East Mabel Street, Tucson, Arizona 85721, United States.
authors.forename: Hyun-Jin
authors.initials: HJ
authors.lastname: Kang
authors.affiliation: Department of Chemistry and Biochemistry and School of Biomedical Sciences, Kent State University , Kent, Ohio 44242, United States.
authors.forename: Yunxi
authors.initials: Y
authors.lastname: Cui
authors.affiliation: Translational Genomics Research Institute , 445 North Fifth Street, Phoenix, Arizona 85004, United States.
authors.forename: Holly
authors.initials: H
authors.lastname: Yin
authors.affiliation: College of Science, University of Arizona , 1040 East Fourth Street, Tucson, Arizona 85721, United States.
authors.forename: Amy
authors.initials: A
authors.lastname: Scheid
authors.affiliation: Translational Genomics Research Institute , 445 North Fifth Street, Phoenix, Arizona 85004, United States.
authors.forename: William P D
authors.initials: WPD
authors.lastname: Hendricks
authors.affiliation: Department of Dermatology, Mayo Clinic , 13400 East Shea Boulevard, Scottsdale, Arizona 85259, United States.
authors.forename: Jessica
authors.initials: J
authors.lastname: Schmidt
authors.affiliation: Department of Dermatology, Mayo Clinic , 13400 East Shea Boulevard, Scottsdale, Arizona 85259, United States.
authors.forename: Aleksandar
authors.initials: A
authors.lastname: Sekulic
authors.affiliation: State Key Laboratory of Medicinal Chemical Biology, College of Chemistry, Nankai University , Tianjin 300071, People's Republic of China.
authors.forename: Deming
authors.initials: D
authors.lastname: Kong
authors.affiliation: Translational Genomics Research Institute , 445 North Fifth Street, Phoenix, Arizona 85004, United States.
authors.forename: Jeffrey M
authors.initials: JM
authors.lastname: Trent
authors.affiliation: BIO5 Institute , 1657 East Helen Street, Tucson, Arizona 85721, United States.
authors.forename: Vijay
authors.initials: V
authors.lastname: Gokhale
authors.affiliation: Department of Chemistry and Biochemistry and School of Biomedical Sciences, Kent State University , Kent, Ohio 44242, United States.
authors.forename: Hanbin
authors.initials: H
authors.lastname: Mao
authors.affiliation: University of Arizona , College of Pharmacy, 1703 East Mabel Street, Tucson, Arizona 85721, United States.|BIO5 Institute , 1657 East Helen Street, Tucson, Arizona 85721, United States.|Arizona Cancer Center , 1515 North Campbell Avenue, Tucson, Arizona 85724, United States.
authors.forename: Laurence H
authors.initials: LH
authors.lastname: Hurley