Down-regulation of PSMD4 can attenuate autophagy, enhance the accumulation of intracellular ROS, and increase the sensitivity of epithelial ovarian cancer to carboplatin by inhibiting the NF-κB pathway

The incidence of ovarian cancer ranks third among female gynecological cancers in the world, and more than 90% of patients are epithelial ovarian cancer (EOC). Carboplatin is the first-line chemotherapy drug for the treatment of EOC patients. However, patients who are resistant to carboplatin often do not benefit from it. Therefore, finding a key molecule that affects carboplatin sensitivity is expected to enhance the efficacy of carboplatin in EOC treatment.

Down-regulation of PSMD4 may inhibit the activation of the NF-κB pathway and autophagy, and up-regulate the level of intracellular ROS accumulation, thereby promoting carboplatin-mediated EOC cell apoptosis and enhancing carboplatin sensitivity.

The human EOC cell line SK-OV-3 and TOV-21G were used in this study. The second-generation sequencing technology was used to sequence the transcripts of carboplatin-resistant EOC cells and parental EOC cells. The bioinformatic analysis of the differentially expressed genes was performed by Gene Ontology (GO) enrichment, Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis. The EOC tissue chip in the Gene Expression Omnibus (GEO) database was also analyzed to screen the target gene. Flow cytometry, Hoechst staining, Western blot, MTS, mitochondrial specific reducing agent (Mito Tempo), and nuclear factor kappa-B (NF-κB) pathway inhibitor (BAY 11-7082) were used to explore the effect of proteasome 26S subunit, non-ATPase 4 (PSMD4) on the autophagy, apoptosis, and reactive oxygen species (ROS) accumulation of carboplatin-resistant EOC cells treated with carboplatin. In vivo, the carboplatin-resistant EOC cell lines treated with PSMD4 knockdown were injected subcutaneously into mice (twelve female BALB/c nude mice) to construct EOC subcutaneous xenograft tumor models.

Based on second-generation sequencing technology and bioinformatics analysis, it was found that PSMD4 is the core molecule in the carboplatin resistance regulatory network in EOC, and its expression is up-regulated in EOC carboplatin-resistant tissues and cells. In vitro and in vivo experimental results show that the down-regulated expression of PSMD4 is closely related to the increase in sensitivity of EOC to carboplatin. Mechanically, we found that inhibiting PSMD4 expression may inhibit the activation of the NF-κB pathway, promote carboplatin-induced ROS accumulation in EOC cells, inhibit EOC cell autophagy, and enhance the sensitivity of EOC to carboplatin. Conclusions: Down-regulation of PSMD4 may inhibit the activation of the NF-κB pathway and autophagy, and up-regulate the level of intracellular ROS accumulation, thereby promoting carboplatin-mediated EOC cell apoptosis and enhancing carboplatin sensitivity.