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TERT, the catalytic subunit of telomerase, is aberrantly activated in most cancers and represents an attractive therapeutic target. However, conventional TERT-targeting strategies, including chemical inhibitors and siRNA, are limited by several issues, such as insufficient efficacy and off-target effects. In this study, we investigated whether dCas9-KRAB-mediated CRISPR interference (CRISPRi) could overcome the limitations by transcriptional repression of TERT without DNA cleavage. We first assessed the efficacy of the dCas9-KRAB system by applying it to H1299 non-small-cell lung cancer cells and observed reduction in TERT expression up to approximately 80% and significant decreases in cell viability and growth. Transcriptome-wide analysis showed limited detectable changes in non-target-gene expression under the conditions tested. Together, the results suggest that dCas9-KRAB-mediated CRISPRi could serve as a proof-of-principle approach for targeted repression of TERT in cancer cells with limited detectable effects on non-target-gene expression.