PSMD9 promotes the malignant progression of hepatocellular carcinoma by interacting with c-Cbl to activate EGFR signaling and recycling

J Exp Clin Cancer Res. 2024 May 14;43(1):142. doi: 10.1186/s13046-024-03062-3.

Abstract

Background: Mounting evidences shows that the ubiquitin‒proteasome pathway plays a pivotal role in tumor progression. The expression of 26S proteasome non-ATPase regulatory subunit 9 (PSMD9) is correlated with recurrence and radiotherapy resistance in several tumor types. However, the role and mechanism of PSMD9 in hepatocellular carcinoma (HCC) progression remain largely unclear.

Methods: PSMD9 was identified as a prognosis-related biomarker for HCC based on analysis of clinical characteristics and RNA-seq data from The Cancer Genome Atlas (TCGA), Gene Expression Omnibus (GEO) and the JP Project of the International Cancer Genome Consortium (ICGC-LIRI-JP). PSMD9 expression was analyzed in cancer tissues and adjacent noncancerous tissues via immunohistochemistry and Western blotting. Multiple in vivo and in vitro experimental techniques (such as CCK-8, colony formation, EdU, and Transwell assays; flow cytometry; Western blotting; quantitative RT-PCR; Coimmunoprecipitation assay and immunofluorescence confocal imaging) were used to assess the functions of PSMD9 in the pathogenesis of HCC.

Results: We found that the expression of PSMD9 was upregulated and associated with a poor prognosis in HCC patients. PSMD9 promoted HCC cell proliferation, migration, invasion and metastasis. Knockdown of PSMD9 significantly inhibited HCC cell proliferation by inducing G1/S cell cycle arrest and apoptosis. Mechanistically, we demonstrated that PSMD9 promoted HCC cell proliferation and metastasis via direct interaction with the E3 ubiquitin ligase c-Cbl, suppresses EGFR ubiquitination, influenced EGFR endosomal trafficking and degradation and subsequently activated ERK1/2 and Akt signaling. In addition, we showed that PSMD9 knockdown sensitized HCC cells to the tyrosine kinase inhibitor erlotinib in vitro and in vivo.

Conclusions: Collectively, our results indicate that PSMD9 drives HCC progression and erlotinib resistance by suppressing c-Cbl mediated EGFR ubiquitination and therefore can be a potential therapeutic target for HCC.

Keywords: EGFR; Hepatocellular carcinoma; PSMD9; Progression; c-Cbl.

MeSH terms

  • Animals
  • Apoptosis
  • Carcinoma, Hepatocellular* / genetics
  • Carcinoma, Hepatocellular* / metabolism
  • Carcinoma, Hepatocellular* / pathology
  • Cell Line, Tumor
  • Cell Movement
  • Cell Proliferation
  • Disease Progression*
  • ErbB Receptors* / genetics
  • ErbB Receptors* / metabolism
  • Female
  • Humans
  • Liver Neoplasms* / genetics
  • Liver Neoplasms* / metabolism
  • Liver Neoplasms* / pathology
  • Male
  • Mice
  • Mice, Nude
  • Middle Aged
  • Prognosis
  • Proteasome Endopeptidase Complex / metabolism
  • Proto-Oncogene Proteins c-cbl* / genetics
  • Proto-Oncogene Proteins c-cbl* / metabolism
  • Signal Transduction*