Identification of mechanism of cancer-cell-specific reactivation of hTERT offers therapeutic opportunities for blocking telomerase specifically in human colorectal cancer

Transcriptional reactivation of hTERT is the limiting step in tumorigenesis. While mutations in hTERT promoter present in 19% of cancers are recognized as key drivers of hTERT reactivation, mechanisms by which wildtype hTERT (WT-hTERT) promoter is reactivated, in majority of human cancers, remain unknown. Using primary colorectal cancers (CRC) we identified Tert INTeracting region 2 (T-INT2), the critical chromatin region essential for reactivating WT-hTERT promoter in CRCs. Elevated β-catenin and JunD level in CRC facilitates chromatin interaction between hTERT promoter and T-INT2 that is necessary to turn on hTERTexpression. Pharmacological screens uncovered salinomycin, which inhibits JunD mediated hTERT-T-INT2 interaction that is required for the formation of a stable transcription complex on the hTERT promoter. Our results showed for the first time how known CRC alterations, such as APC, lead to WT-hTERT promoter reactivation during stepwise-tumorigenesis and provide a new perspective for developing cancer-specific drugs.Agency for Science, Technology and Research (A*STAR)Ministry of Education (MOE)National Research Foundation (NRF)Published versionNational Research Foundation under its Competitive Research Programme [NRF-CRP17-2017-02 to V.T.]; Agency for Science Technology and Research, Singapore (A*STAR) for funding and supporting the Tergaonkar laboratory and this project; NRF Singapore and the Singapore Ministry of Education under its Research Centres of Excellence initiative; Singapore Ministry of Education Academic Research Fund Tier 2 grant [MOET2EP30120-0009 to M.J.F.]. Funding for open access charge: The V.T. laboratory is supported by the National Research Foundation-Competitive Research Programme [NRF-CRP17-2017-02]; IMCB A*STAR