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OTUD4-Mediated GSDME Deubiquitination Enhances Radiosensitivity in Nasopharyngeal Carcinoma by Inducing Pyroptosis
43 Pages Posted: 9 Aug 2022
More...Abstract
Background: Radioresistance is the primary cause of nasopharyngeal carcinoma (NPC) treatment failure. Previous studies have focused on the deficits in cellular apoptosis as a mechanism for radioresistance; however, additional potential death modes involved in modulating radiosensitivity of NPC have not been explored.
Methods: Pyroptosis was assessed by phase-contrast imaging, LDH release assays, live cell imaging, and Western blotting. In vitro and in vivo assays were used to investigate the function of gasdermin E (GSDME) and ovarian tumor family deubiquitinase 4 (OTUD4). NPC tissues were analyzed using Western blotting, immunohistochemistry, and real-time PCR. The molecular mechanism was determined using immunoprecipitation assays and mass spectrometry.
Findings: Live cell imaging revealed that 40 - 75% of irradiation-induced dead NPC cells were pyroptotic cells. Furthermore, irradiation-induced pyroptosis is triggered by GSDME, which are cleaved by activated caspase-3 in the intrinsic mitochondrial pathway. Additionally, GSDME was significantly downregulated in radioresistant NPC specimens. Low GSDME expression was a predictor of worse prognosis and conferred NPC radioresistance both in vitro and in vivo. Mechanistically, OTUD4 deubiquitinated and stabilized GSDME, enhancing radiosensitivity of NPC cells by promoting pyroptosis. Clinically, OTUD4 was significantly correlated with GSDME in NPC biopsies, and patients with low expression of both OTUD4 and GSDME suffered the worst radiotherapy response and survival.
Interpretation: GSDME-dependent pyroptosis is a critical determinant of radiosensitivity in NPC, and is modulated by OTUD4 via deubiquitinating and stabilizing GSDME. These findings reveal a promising novel direction to investigate radioresistance and suggest potential therapeutic targets for sensitizing NPC to radiotherapy.
Funding Information: This work was supported by the National Key R&D Program of China (grant number 2018YFC1313400) and the National Natural Science Foundation of China (grant numbers 81773110, 81872469, 82073330).
Declaration of Interests: Authors declare that they have no competing interests.
Ethics Approval Statement: The animal experiments were approved by the Animal Research Committee of Sun Yat-sen University Cancer Center and were performed in accordance with established guidelines. The use of human NPC tissues was reviewed and approved by the ethical committee of Sun Yat-sen University Cancer Center, and informed consent was obtained from patients. The samples were retrospectively acquired from the department of nasopharyngeal carcinoma archives of Sun Yat-sen University Cancer Center.
Keywords: OTUD4, GSDME, pyroptosis, radioresistance, nasopharyngeal carcinoma
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