Targeting YRDC blocks codon-biased FABP7 translation and lipid droplet formation to overcome chemoresistance in glioblastoma.

Dysregulation of transfer RNA (tRNA) modification and reprogramming of codon-biased translation are commonly associated with cancer initiation and progression. However, their roles in chemoresistance and tumor recurrence remain poorly understood, especially in glioblastoma (GBM). This study establishes the tRNA-modifying enzyme YrdC N6-Threonylcarbamoyltransferase Domain Containing (YRDC) as a key mediator of temozolomide (TMZ) resistance in GBM. YRDC catalyzes the formation of N6-threonylcarbamoyladenosine (t6A) on ANN-decoding tRNAs (A denotes adenosine, and N denotes any nucleotide). YRDC expression is elevated in TMZ-resistant models and recurrent GBM, correlating with poor patient prognosis. Mechanistically, YRDC drives ANN codon-biased translation of target mRNAs, most notably encoding the fatty acid-binding protein FABP7. Elevated FABP7 induces lipid droplet accumulation, which sequesters TMZ-induced reactive oxygen species to mitigate oxidative stress and confer chemoresistance. Targeting this axis, we developed HY-Q66655, a novel blood-brain-barrier-penetrant YRDC inhibitor identified via virtual screening. HY-Q66655 directly inhibits YRDC, suppresses FABP7 translation, depletes lipid droplets, and acts synergistically with TMZ to inhibit tumor growth in vitro and in patient-derived orthotopic xenografts. The YRDC/FABP7 pathway is clinically associated with GBM recurrence, and HY-Q66655 demonstrates broad-spectrum anti-tumor activity across malignancies, revealing a tRNA modification-dependent mechanism and a potential therapeutic strategy.