The study shows that losing the enzyme LIPT1 in cancer cells causes a buildup of a metabolite (2‑HG) that makes DNA replication harder, leading to DNA damage that can be targeted with PARP inhibitors. This is a molecular cancer‑biology finding and does not involve palmitoyl‑dipeptide‑6 or suggest any lifestyle or supplement changes.

Replication stress (RS) and altered metabolism are two hallmarks of cancer, yet how metabolic perturbations contribute to RS remains poorly understood. Lipotransferase 1 (LIPT1) catalyzes the covalent attachment of lipoic acid to mitochondrial 2-ketoacid dehydrogenases, sustaining flux through the tricarboxylic acid (TCA) cycle. Loss of LIPT1 causes accumulation of 2-hydroxyglutarate (2-HG), which is known to inhibit α-ketoglutarate (α-KG)-dependent histone demethylases and promotes heterochromatin formation. Here, we show that 2-HG-driven heterochromatin impedes replication fork progression, causing fork stalling and RS in LIPT1-deficient cancer cells. To bypass stalled forks, PrimPol-mediated repriming resumes DNA synthesis but leaves behind single-stranded DNA (ssDNA), which requires poly (ADP-ribose) polymerase 1 (PARP1) for repair. Furthermore, nascent DNA at reprimed forks undergoes MRE11-dependent degradation, further destabilizing replication fork integrity. Consequently, LIPT1 deficiency promotes replication and genome instability, and therapeutic vulnerability to PARP inhibitor. Together, these findings reveal a mechanistic link between mitochondrial lipoylation and replication fork stability, uncovering a metabolic basis for genome instability in cancer.