Abstract 3272: PJA1 inhibits docetaxel-induced pyroptosis and results in chemoresistance in nasopharyngeal carcinoma

Abstract

Abstract Background: Nasopharyngeal carcinoma (NPC) is highly prevalent in South China. More than 70% of patients are diagnosed with locoregionally advanced NPC (LA-NPC) at initial presentation, and the addition of induction chemotherapy (IC) to concurrent chemoradiotherapy is recommended for these patients. However, chemoresistance is a main reason for treatment failure in NPC patients, and the exact regulatory mechanism underlying chemoresistance in NPC remains to be elucidated. Methods: A gene expression dataset and STRING database were used to identify core module and gene that are related to the efficacy of docetaxel-cisplatin-5-fluorouracil (TPF) IC in NPC patients. In vitro and in vivo functional experiments were used to test the effects of PJA1 on docetaxel chemoresistance of NPC cells. The flow cytometric analysis, western blot, and lactate dehydrogenase (LDH) release assays were performed to determine the effects of PJA1 on GSDME-mediated cell pyroptosis. Co-immunoprecipitation, mass spectrometry, immunofluorescence staining, and ubiquitination assays were performed to explore the regulatory manners between PJA1 and PGAM5-DRP1 axis. Finally, multiplex immunofluorescence and immunohistochemical staining were used to evaluate the clinical significance of PJA1 -PGAM5-DRP1 axis in patients with NPC. Results: PJA1 was identified as a key E3 ligase of the top-ranked module ubiquitin-proteasome system dysregulation that involved in NPC chemoresistance, which was highly expressed in NPC patients with nonresponse to the TPF IC. PJA1 facilitated the docetaxel resistance of NPC cells through inhibiting the GSDME-mediated pyroptosis. Mechanistically, PJA1 promoted the degradation of the mitochondrial protein PGAM5 by increasing its K48-linked ubiquitination at K88, further increasing the phosphorylation of DRP1 at S637 and reducing the mitochondrial reactive oxygen species (ROS) production, in turn resulting in a suppressive of GSDME-mediated pyroptosis. PGAM5 knockdown fully restored the docetaxel sensitization effect of PJA1 knockdown. Moreover, RTA402, a pharmacological inhibitor of PJA1, enhanced the docetaxel sensitivity of NPC cells. Clinically, high PJA1 expression indicated resistance to TPF IC an inferior survival in NPC patients. Conclusions: Our study emphasizes the essential role of E3 ligase PJA1 in regulating chemoresistance in NPC and provides new therapeutic strategies for NPC patients based on targeting the ubiquitin-proteasome system. Citation Format: Na Liu, Ying-Qing Li, Sheng-Yan Huang. PJA1 inhibits docetaxel-induced pyroptosis and results in chemoresistance in nasopharyngeal carcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 3272.