CRlSPR/Cas9 screening revealed BlRC6-AS1/BlRC6 mediates abiraterone resistance via NHEJ pathway-dependent A20 degradation in prostate cancer

Abiraterone acetate serves as the first-line therapeutic agent for prostate cancer (PCa) treatment. However, drug resistance frequently emerges. Employing a genome-wide CRISPR/Cas9 library screening strategy, we identified 523 long non-coding RNAs (lncRNAs) and 2183 protein-coding genes associated with abiraterone resistance. Notably, a pair of sense-antisense genes, BIRC6-AS1/BIRC6, was demonstrated to be a pivotal driver for abiraterone resistance. BIRC6-AS1 depletion led to a reduction in both the mRNA and protein levels of BIRC6. Moreover, depletion of either BIRC6-AS1 or BIRC6 enhanced the chemosensitivity of PCa cells to abiraterone both in vitro and in vivo settings. Further investigation revealed that BIRC6-AS1 stabilized the mRNA of BIRC6 through interaction with ILF2. Diminishing either BIRC6-AS1 or BIRC6 predominantly suppressed non-homologous end joining (NHEJ) repair activity, resulting in the disassembly of 53BP1 foci at DNA damage sites and an increased accumulation of DNA damage in PCa cells induced by abiraterone. Mechanistically, BIRC6 interacted with A20 and facilitated the K48-linked ubiquitination and subsequent degradation of A20 at the K337 residue. Additionally, A20 knockdown effectively reversed the abiraterone sensitivity induced by BIRC6-AS1 depletion. Collectively, we conducted a comprehensive screen to identify lncRNAs and protein-coding genes associated with abiraterone resistance and proposed that targeting BIRC6-AS1/BIRC6 axis represents a promising strategy to overcome abiraterone resistance in prostate cancer.