Shanmugam, Ozturk, M. B., Low, J.-L., Akincilar, S. C., Chua, J. Y. H., Thangavelu, M. T., Periyasamy, G., DasGupta, R., & Tergaonkar, V. (2022). Genome-wide screens identify specific drivers of mutant hTERT promoters. Proceedings of the National Academy of Sciences, 119(3), e2105171119. https://doi.org/10.1073/pnas.2105171119
Cancer-specific hTERT promoter mutations reported in 19% of cancers result in enhanced telomerase activity. Understanding the distinctions between transcriptional regulation of wild-type (WT) and mutant (Mut) hTERT promoters may open up avenues for development of inhibitors which specially block hTERT expression in cancer cells. To comprehensively identify physiological regulators of WT- or Mut-hTERT promoters, we generated several isogenic reporter cells driven by endogenous hTERT loci. Genome-wide CRISPR-Cas9 and small interfering RNA screens using these isogenic reporter lines identified specific regulators of Mut-hTERT promoters. We validate and characterize one of these hits, namely, MED12, a kinase subunit of mediator complex. We demonstrate that MED12 specifically drives expression of hTERT from the Mut-hTERT promoter by mediating long-range chromatin interaction between the proximal Mut-hTERT promoter and T-INT1 distal regulatory region 260 kb upstream. Several hits identified in our screens could serve as potential therapeutic targets, inhibition of which may specifically block Mut-hTERT promoter driven telomerase reactivation in cancers.
Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0)
This research / project is supported by the National Research Foundation - Competitive Research Programme
Grant Reference no. : NRF-CRP17-2017-02
This research / project is supported by the National Medical Research Council - Young Individual Research Grant
Grant Reference no. : NMRC/OFYIRG/18MAY-0008