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CRISPR/Cas9 library screening uncovered methylated PKP2 as a critical driver of lung cancer radioresistance by stabilizing β-catenin


Radiation resistance is a major cause of lung cancer treatment failure. Armadillo (ARM) superfamily proteins participate in various fundamental cellular processes; however, whether ARM proteins regulate radiation resistance is not fully understood. Here, we used an unbiased CRISPR/Cas9 library screen and identified plakophilin 2 (PKP2), a member of the ARM superfamily of proteins, as a critical driver of radiation resistance in lung cancer. The PKP2 level was significantly higher after radiotherapy than before radiotherapy, and high PKP2 expression after radiotherapy predicted poor overall survival (OS) and postprogression survival (PPS). Mechanistically, mass spectrometry analysis identified that PKP2 was methylated at the arginine site and interacted with protein arginine methyltransferase 1 (PRMT1). Methylation of PKP2 by PRMT1 stabilized β-catenin by recruiting USP7, further inducing LIG4, a key DNA ligase in nonhomologous end-joining (NHEJ) repair. Concomitantly, PKP2-induced radioresistance depended on facilitating LIG4-mediated NHEJ repair in lung cancer. More strikingly, after exposure to irradiation, treatment with the PRMT1 inhibitor C-7280948 abolished PKP2-induced radioresistance, and C-7280948 is a potential radiosensitizer in lung cancer. In summary, our results demonstrate that targeting the PRMT1/PKP2/β-catenin/LIG4 pathway is an effective approach to overcome radiation resistance in lung cancer.

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Fig. 1: Genome-wide CRISPR/Cas9 screening identified PKP2 as a driver of lung cancer radioresistance.
Fig. 2: PKP2 stabilizes β-catenin to induce LIG4 transcription.
Fig. 3: LIG4 is a key player in PKP2-mediated radioresistance.
Fig. 4: PKP2 recruits USP7 to enhance the deubiquitination and stability of β-catenin.
Fig. 5: Arginine methylation of PKP2 by PRMT1 enhances the ability to bind to β-catenin.
Fig. 6: PKP2 R101 methylation promotes lung cancer radioresistance.
Fig. 7: The PRMT1 inhibitor C-7280948 contributes to overcoming radioresistance.


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This study was supported by grants from the special fund for Jiangxi Key Laboratory (20171BCD40026 to YS), the Jiangxi Provincial Natural Science Foundation of China (20192BAB215039 to YS) and the Natural Science Foundation of China (81772821 to KH).

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CC, XP, SL, JY, CL and JT performed all of the experiments and data analysis. CC and YS conceived the research design, experiments, and data analysis. KH, GH, WM and YS prepared and wrote the paper.

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Correspondence to Yi Sang.

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Cheng, C., Pei, X., Li, SW. et al. CRISPR/Cas9 library screening uncovered methylated PKP2 as a critical driver of lung cancer radioresistance by stabilizing β-catenin. Oncogene 40, 2842–2857 (2021).

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