lncRNA EGFR-AS1 promotes DNA damage repair by enhancing PARP1-mediated PARylation

DNA damage repair is vital for maintaining genetic stability and integrity of cells that encounter DNA-damaging agents. So far, a series of multifunctional proteins and long noncoding RNAs (lncRNAs) have been demonstrated to participate in the DNA damage response (DDR). However, our current understanding of detailed mechanisms of DNA damage repair remains limited. Herein, we report that lncRNA EGFR-AS1 is functionally involved in DDR in both non–small-cell lung cancer cells and noncancerous cells. Using DNA repair reporter, we found that EGFR-AS1 overexpression significantly enhances the efficiency of both the classical nonhomologous end-joining and homologous recombination pathways. Through the lncRNA interactome, we identified a set of DNA repair factors, including the canonical DNA damage sensor PARP1 and NAD+ supplier NMNAT1. Upon DNA damage, DNA-activated PARP1 binds to EGFR-AS1 and forms a ternary complex with NMNAT1, promoting NAD+ utilization and poly(ADP-ribosyl)ation (PARylation) of PARP1. Additionally, EGFR-AS1 also facilitates displacing PARP1 from the sites of damaged DNA. Our findings demonstrate a lncRNA-associated PARP1 activation and displacement in DDR and highlight the potential of EGFR-AS1 as a target for cancer therapy.