A small-molecule drug inhibits autophagy gene expression through the central regulator TFEB.

ABSTRACT

Autophagy supports the fast growth of established tumors and promotes tumor resistance to multiple treatments. Inhibition of autophagy is a promising strategy for tumor therapy. However, effective autophagy inhibitors suitable for clinical use are currently lacking. There is a high demand for identifying novel autophagy drug targets and potent inhibitors with drug-like properties. The transcription factor EB (TFEB) is the central transcriptional regulator of autophagy, which promotes lysosomal biogenesis and functions and systematically up-regulates autophagy. Despite extensive evidence that TFEB is a promising target for autophagy inhibition, no small molecular TFEB inhibitors were reported. Here, we show that an United States Food and Drug Administration (FDA)-approved drug Eltrombopag (EO) binds to the basic helix-loop-helix-leucine zipper domain of TFEB, specifically the bottom surface of helix-loop-helix to clash with DNA recognition, and disrupts TFEB-DNA interaction in vitro and in cellular context. EO selectively inhibits TFEB's transcriptional activity at the genomic scale according to RNA sequencing analyses, blocks autophagy in a dose-dependent manner, and increases the sensitivity of glioblastoma to temozolomide in vivo. Together, this work reveals that TFEB is targetable and presents the first direct TFEB inhibitor EO, a drug compound with great potential to benefit a wide range of cancer therapies by inhibiting autophagy.