CRISPR-Cas9 Screen Identifies DYRK1A as a Target for Radiotherapy 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 intrinsic and acquired radioresistance. Identifying the molecular mechanisms that impair
the efficacy of radiotherapy and targeting these pathways are essential to improve the radiation
response 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 enhance the therapeutic
effect through the development and application of targeted inhibitors combined with radiotherapy.
We transduced pancreatic cancer cells with a protein kinase library; 2D and 3D library cells were
irradiated daily with a single dose of up to 2 Gy for 4 weeks for 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 function sensitizes cells
to radiotherapy. Additionally, we demonstrated that the harmine-targeted suppression 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 radiosensitizers, and provide novel
strategies for overcoming the tolerance of pancreatic cancer to radiotherapy.