AURKB and PI3K/AKT/mTOR pathways converge to regulate TERT expression

Telomere length maintenance, critical for cancer progression, can be driven by TERT promoter mutations (TERTp ^MUT ), which are markers of poor prognosis across multiple cancers. Their tumor-specificity also makes them attractive chemotherapeutic targets. Here, we identified previously uncharacterized pathways regulating TERTp ^MUT activity by inserting a luciferase reporter downstream of TERTp ^MUT in SW1736 anaplastic thyroid cancer cells via CRISPR-Cas9, generating SW1736^TERT/LUC, and screening a 218-kinase inhibitor library. Beyond MAPK regulation, we found co-regulatory roles for PI3K/AKT/mTOR1 signaling and the cell cycle via Aurora kinase B (AURKB). Further analyses using quantitative PCR, immunoprecipitation (IP), and chromatin IP in thyroid cell models revealed that although both TERTp ^MUT and wild-type promoters are governed by these pathways, distinct factors mediate each mechanism. Specifically, AURKB, via REST, is recruited to TERTp ^MUT by TRIM28. These findings highlight TRIM28 as a promising therapeutic target for TERTp ^MUT -driven thyroid cancers.