ATP2B4 driven chromatin compaction exacerbates pancreatic cancer radiotherapy resistance

Abstract The intrinsic radio-resistance of pancreatic cancer cells significantly hinders therapeutic efficacy. However, the precise molecular mechanisms underlying this resistance remain inadequately understood and warrant further investigation. Here, using the high-throughput metabolic CRISPR library screening and RNA sequencing, we identified an ATPase Plasma Membrane Ca 2+ Transporting 4 (ATP2B4) as a novel molecular contributor to radiotherapy resistance in pancreatic cancer both in vitro and in vivo. Functionally, micrococcal nuclease assay, drug rescue assays, along with overexpression and silencing experiments, revealed that knockout of ATP2B4 induced chromatin decompaction through the downregulation of histone H1.0, thereby exacerbating DNA damage and increasing RT-induced cell apoptosis. Mechanistically, TurboID-based mass spectrometry and immunoprecipitation (IP) demonstrated that ATP2B4 stabilized ELAVL1, maintaining its function, which further regulated the mRNA stability of histone H1.0. Taken together, our findings identified ATP2B4 as a key regulator of chromatin compaction and DNA damage response, positioning it as a potential biomarker for predicting RT outcomes and a promising therapeutic target for overcoming RTR.