Prostate cancer (PCa) has become a worldwide health burden among men. Previous studies have suggested that Cellular Retinoic Acid Binding Protein 2 (CRABP2) significantly affects the regulation of cell proliferation, motility, and apoptosis in multiple cancers, yet the effect of CRABP2 on PCa is poorly reported. The CRABP2 expression in different PCa cell lines and its effect on different cellular functions were various. While CRABP2 promotes cell migration and invasion, it appears to inhibit cell proliferation specifically in PC-3 cells. However, the proliferation of DU145 and 22RV1 cells did not appear to be significantly affected by CRABP2. Besides, CRABP2 had no influence on the cell cycle distribution of PCa cells. RNA-seq assay showed that overexpressing CRABP2 up-regulated Laminin subunit beta-3 (LAMB3) mRNA expression, and the enrichment analyses revealed that the differentially expressed genes were enriched in PI3K/AKT and MAPK signaling pathway. The following WB experiments also confirmed the up-regulated LAMB3 protein level and the activation of PI3K/AKT and MAPK signaling pathways. Moreover, overexpressing CRABP2 inhibited tumor growth significantly in vivo. In conclusion, CRABP2 facilitates cell migration and invasion by activating PI3K/AKT and MAPK signaling pathways through upregulating LAMB3 in PCa.
Despite the initial efficacy of enzalutamide in castration-resistant prostate cancer (CRPC), inevitable resistance remains a significant challenge. Here, the synergistic induction of copper-dependent cell death (cuproptosis) in CRPC cells is reported by enzalutamide and copper ionophores (elesclomol/disulfiram). Mechanistically, enzalutamide treatment increases mitochondrial dependence in CRPC cells, rendering them susceptible to cuproptosis, as evidenced by specific reversal with the copper chelator tetrathiomolybdate. This susceptibility is characterized by hallmarks of cuproptosis, including lipoylated protein aggregation and iron-sulfur cluster protein instability. Interestingly, the mitochondrial matrix reductase, FDX1, specifically correlates with elesclomol sensitivity, suggesting a potential mechanistic divergence between the two copper ionophores. Notably, this synergistic effect extends beyond in vitro models, demonstrating efficacy in 22Rv1 xenografts, mouse Pten p53 knockout organoids. Importantly, enzalutamide significantly enhances copper ionophore-mediated cytotoxicity in enzalutamide-resistant cells. Collectively, these findings indicate that enzalutamide and copper ionophores synergistically induce cuproptosis, offering a promising therapeutic avenue for CRPC, potentially including enzalutamide-resistant cases.
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