AGD1/USP10/METTL13 complexes enhance cancer stem cells proliferation and diminish the therapeutic effect of docetaxel via CD44 m6A modification in castration resistant prostate cancer

Background : Most patients with prostate cancer inevitably progress to castration-resistant prostate cancer (CRPC), at which stage chemotherapeutics like docetaxel become the first-line treatment. However, chemotherapy resistance typically develops after an initial period of therapeutic efficacy. Increasing evidence indicates that cancer stem cells confer chemotherapy resistance via exosomes. This study demonstrated that AGD1, derived from prostate cancer stem-like cells, enhances the stemness of prostate cancer cells and reduces the therapeutic effect of docetaxel in CRPC. Methods : Quantitative real-time PCR (qPCR) was employed to determine the expression levels of AGD1 and METTL13 mRNAs in CRPC-like cells and exosomes. Protein expression levels were examined using Western blots and dot blots. The potential functions of AGD1 and METTL13 in CRPCs were investigated through CCK-8, Transwell, EDU incorporation assays, Annexin V-FITC/PI staining, and sphere formation assays. To uncover the underlying mechanisms of AGD1, RNA pull-down assay, RIP, Co-Immunoprecipitation (Co-IP), mass spectrometry (MS), and Methylated RNA immunoprecipitation (MeRIP) were performed. The effects of AGD1 and METTL13 on CRPC development and metastasis under docetaxel treatment were analyzed using a xenograft mouse model, an organoid model and liposomal-chitosan nanocomplex drug delivery systems. Additionally, liposomal-chitosan nanocomplex drug delivery systems were designed to explore AGD1's role in regulating docetaxel treatment resistance in CRPC. Results : AGD1 expression was upregulated in CRPC-like cells and exosomes. Downregulating AGD1 enhanced the sensitivity of CRPCs to docetaxel treatment by inhibiting their stemness, with the reverse also being true. RNA pull-down, combined with mass spectrometry (MS), Co-IP, and RIP assays, demonstrated that AGD1 binds to METTL13 and USP10, forming a complex that facilitates METTL13 protein degradation through USP10-induced ubiquitination. MeRIP assays revealed that METTL13 transcriptionally controls the mRNA decay of CD44 via m6A methylation. Additionally, this process activates the pSTAT3/PI3K-AKT signaling pathway. Organoid models and liposomal-chitosan nanocomplex drug delivery systems showed that reducing AGD1 expression enhances the therapeutic effect of docetaxel in CRPC. Conclusions : AGD1 mediates the stemness and apoptosis of PCSCs and promotes docetaxel treatment resistance by enhancing tumor growth and metastasis through USP10/METTL13-mediated CD44 mRNA decay in CRPC.