Enhancer RNA promotes resistance to radiotherapy in bone-metastatic prostate cancer by m(6)A modification

Rationale: Prostate cancer metastasizes to the bone with the highest frequency and exhibits high resistance to (177)Lu-prostate-specific membrane antigen (PSMA) radioligand therapy. Little is known about bone metastatic prostate cancer (mPCa) resistance to radiation. Methods: We filtered the metastatic eRNA using RNA-seq, MeRIP-seq, RT-qPCR and bioinformation. Western blot, RT-qPCR, CLIP, co-IP and RNA pull-down assays were used for RNA/protein interaction, RNA or protein expression examination. MTS assay was used to determine cell viability in vitro, xenograft assay was used to examine the tumor growth in mice. Results: In this study, we screened and identified bone-specific N6 adenosine methylation (m(6)A) on enhancer RNA (eRNA) that played a post-transcriptional functional role in bone mPCa and was correlated with radiotherapy (RT) resistance. Further data demonstrated that RNA-binding protein KHSRP recognized both m(6)A at eRNA and m(6)Am at 5'-UTR of mRNA to block RNA degradation from exoribonuclease XRN2. Depletion of the MLXIPe/KHSRP/PSMD9 regulatory complex inhibited tumor growth and RT sensitization of bone mPCa xenograft in vitro and in vivo. Conclusions: Our findings indicate that a bone-specific m(6)A-modified eRNA plays a vital role in regulating mPCa progression and RT resistance and might be a novel specific predictor for cancer RT.