DYRK1A in pancreatic cancer. CRISPR-Cas9 screen identifies DYRK1A as a target for radio-therapy sensitization in pancreatic cancer

Although radiation therapy has recently made great advances in cancer treatment, the majority of patients diagnosed with pancreatic cancer (PC) cannot achieve satisfactory outcomes due to in-trinsic and acquired radioresistance. Identifying the molecular mechanisms that impair the effi-cacy of radiotherapy and targeting these pathways are essential to improve the radiation re-sponse of PC patients. Our goal is to identify sensitive targets for pancreatic cancer radiotherapy (RT) using the kinome-wide CRISPR-Cas9 loss-of-function screen, and to enhance the therapeutic effect through the development and application of targeted inhibitors combined with radiother-apy. We transduced pancreatic cancer cells with a protein kinase library, 2D and 3D library cells were daily irradiated with a single dose of up to 2 Gy for 4 weeks at a total of 40 Gy using an X-ray generator. Sufficient DNA was collected for next-generation deep sequencing to identify candidate genes. In this study, we identified several cell cycle checkpoint kinases and DNA damage related kinases in 2D- and 3D-cultivated cells, including DYRK1A, whose loss of func-tion sensitizes cells to radiotherapy. Additionally, we demonstrated that harmine-targeted sup-pression of DYRK1A used in conjunction with radiotherapy increases DNA double strand breaks (DSBs) and impairs homologous repair (HR), resulting in more cancer cell death. Our results support the use of CRISPR-Cas9 screening to identify new therapeutic targets, develop radiosensi-tizer, and provide novel strategies for overcoming the tolerance of pancreatic cancer to radio-therapy.