Methylation-induced silencing of AZGP1 enhances prostate cancer metastasis by stimulating tumoral glycolysis

Abstract Background Metastasis is the primary cause of mortality in patients with prostate cancer (PCa), yet effective treatments remain scarce. Identifying reliable biomarkers and understanding their underlying mechanisms is crucial for advancing clinical management. Methods Firstly, we integrated single-cell and bulk transcriptomic data and employed the Scissor tool to characterize tumor cells with metastatic advantages (termed metastatic cells). Then, independent predictive genes for metastasis were identified through univariate and multivariate regression analyses. The role of hub genes in PCa metastasis was further validated using multiple large datasets, malignant phenotype experiments, in vivo metastatic models, and a clinical-sample-based immunohistochemical cohort. Further, we explored the metabolic characteristics related to hub genes through unbiased functional annotation, and validated the upregulated glycolysis by measuring l-lactic acid production, extracellular acidification rates (ECAR), and oxygen consumption rates (OCR). Finally, multi-omics data were employed to investigate the promoter-methylation-dependent regulation of alpha-2-glycoprotein 1 (AZGP1) transcription, with methylation confirmed through PCa cell-based methylation-specific PCR (MSP) assays. Results AZGP1 was identified as an independent protective predictor of metastasis, which was validated in vitro and in vivo. Metabolic functional annotation revealed that glycolysis was upregulated in AZGP1-positive luminal cells. Consistently, overexpression of AZGP1 in PCa cells was associated with lower l-lactic acid levels, reduced ECAR, and increased OCR. In addition, DNA methylation at the cg26429636 region was linked to decreased transcriptional expression of AZGP1. MSP assays revealed an unmethylated pattern in PCa cells with high AZGP1 expression, and higher methylation levels in AZGP1-low cells. Conclusions Promoter methylation of AZGP1 leads to reduced transcriptional expression, thereby promoting glycolysis in tumor cells and facilitating metastasis. The detection of AZGP1 methylation levels offers a valuable reference for dynamic surveillance of PCa metastasis.