Loss of FTSJ3 promotes R-loop-associated DNA damage and facilitates chemosensitivity in lung cancer cells

R-loop accumulation has emerged as a critical factor that induces DNA damage and compromises genomic integrity. However, the regulatory mechanisms governing the R-loop-induced DNA damage remain unclear. Here, FTSJ3 was determined to be a pivotal regulator of R-loop homeostasis and genomic stability. We demonstrated that FTSJ3 was specifically recruited to R-loop structures, where it prevented DNA damage by suppressing excessive R-loop formation. FTSJ3 expression was significantly upregulated in multiple cancer types, and its elevated expression levels correlated with unfavorable survival in patients with lung adenocarcinoma (LUAD). FTSJ3 depletion increased R-loop-dependent DNA damage. Inhibiting FTSJ3 expression sensitized lung cancer cells to cisplatin both in vitro and in vivo. FTSJ3 could be a genome guardian that limits R-loop-associated damage, suggesting its potential role as a cancer intervention therapeutic target and a predictive biomarker for chemotherapy responsiveness.