A novel nuclear RNA HSD52 scaffolding NONO/SFPQ complex modulates DNA damage repair to facilitate temozolomide resistance

Abstract Background Temozolomide (TMZ) is used in the treatment of glioblastoma (GBM). However, the primary obstacle remains the emergence of TMZ chemotherapy resistance. NONO and SFPQ are multifunctional nuclear proteins involved in genome stability and gene regulation. However, the specific role of NONO and SFPQ in TMZ resistance of GBM remains to be explored. Methods RIP-chip and RNA microarray of TMZ-resistant and parental cells were performed for the gain of HSD52. The effects of HSD52 on TMZ resistance were investigated through in vitro assays, intracranial xenograft and GBM organoid models. The underlying mechanisms were explored by DNA methylation chip, RIP, RNA pulldown assays, among others. GBM clinical samples were rolled in to investigate the clinical significance of HSD52. Results We identified a novel non-coding RNA, HSD52, that was highly expressed in TMZ-resistant GBM and facilitated the interaction between NONO and SFPQ. H3 ubiquitination attenuation and reduced DNMT1 recruitment increased HSD52 transcription via DNA hypo-methylation. HSD52 formed an RNA duplex with UFL1 mRNA, thereby promoting NONO/SFPQ complex binding to UFL1 mRNA and enhancing its stability, and then contributed to TMZ resistance through activating ATM signaling pathway. In vivo xenograft and GBM organoid models showed significant repression in tumor growth after HSD52 knockout with TMZ treatment. In GBM clinical samples, HSD52 was responsible for the malignant progression and TMZ resistance. Conclusions Our results revealed that HSD52 could serve as a promising therapeutic target to overcome TMZ resistance, improving the clinical efficacy of TMZ chemotherapy in GBM.