The Werner syndrome ATP-dependent helicase (WRN) gene encodes a RecQ family DNA helicase-exonuclease critical for maintaining genomic stability. WRN participates in DNA repair, replication, recombination, and telomere maintenance, with its loss-of-function mutations causing Werner syndrome—a premature aging disorder characterized by genomic instability and increased cancer susceptibility. WRN-deficient cells exhibit hypersensitivity to DNA-damaging agents and impaired resolution of replication stress, highlighting its essential role in DNA damage response. Recent studies reveal synthetic lethality between WRN deficiency and microsatellite instability (MSI) in cancers, suggesting WRN as a promising therapeutic target for MSI-high tumors. Small-molecule WRN inhibitors are under investigation for selective anticancer effects. Further research is needed to elucidate WRN\'s multifaceted roles in aging and cancer, and to develop targeted therapies leveraging WRN dependency in specific cancer contexts.