PRKDC Induces Chemoresistance in Osteosarcoma by Recruiting GDE2 to Stabilize GNAS and Activate AKT

Chemoresistance is one of the major causes of poor prognosis in osteosarcoma. Thus far, the therapeutic alternative for osteosarcoma is quite limited, thereby increasing sensitivity of the currently used drugs is an effective way to improve outcome of patients. In this study, through a Kinome-wide CRISPR screen, we identified PRKDC as a critical determinant of Doxorubicin (DOX) sensitivity in osteosarcoma. Clinical sample analysis and functional experiments demonstrated that PRKDC is hyperactivated in osteosarcoma and that knockdown of PRKDC significantly increased sensitivity of osteosarcoma to DOX. Mechanistically, PRKDC could recruit and bind with GDE2 to augment the stability of GNAS. The increased GNAS protein subsequently activate Akt S473 and T308 phosphorylation and mediated DOX sensitivity. We also showed that the PRKDC inhibitor AZD7648 and DOX could synergize with each other and intensely suppressed the growth of osteosarcoma in mice xenograft models and human organoids. In conclusion, these results revealed a novel PRKDC-GDE2-GNAS-Akt regulatory axis in DOX sensitivity and provided targetable candidates for improving therapeutic efficacy of DOX in osteosarcoma.