Allele-Specific CG/CCWGG Methylation of the PSA Promoter Discriminates Aggressive, Indolent, and Benign Prostate Cell Lines and Is Involved in the Regulation of PSA Expression

TL;DR

This study shows how DNA methylation patterns in the PSA promoter differ between aggressive, indolent, and benign prostate cell lines, offering new insights for improving prostate cancer diagnostics.

Contribution

The study identifies distinct allele-specific CG/CCWGG methylation patterns in the PSA promoter that distinguish different prostate states.

Findings

Aggressive PC3 cells show biallelic PSA promoter methylation and gene silencing.

LNCaP cells have unmethylated promoters with biallelic PSA expression.

BPH1 cells display monoallelic methylation but no PSA expression, suggesting RNA decay or imprinting defects.

Abstract

Prostate-specific antigen remains a cornerstone biomarker for prostate cancer diagnosis and management. However, the molecular mechanisms regulating its expression, particularly through DNA methylation, are not fully understood. Here, we report a comprehensive analysis of allele-specific CpG and CCWGG methylation in the proximal PSA promoter across aggressive (PC3), indolent (LNCaP), benign (BPH1), and normal (HPrEpiC) prostate cell lines and provide insights into the unique methylation patterns associated with these states. Our findings reveal that PC3 cells, representing an aggressive PCa phenotype, exhibit complete biallelic methylation of the PSA promoter, leading to PSA gene silencing. Conversely, LNCaP cells display a fully unmethylated promoter with biallelic PSA expression. Interestingly, BPH1 cells display a monoallelic CG/CCWGG methylation pattern, yet fail to express PSA, suggesting imprinting defects or RNA decay mechanisms. Notably, acquisition of biallelic PSA promoter methylation status in PC3 was accompanied by upregulation of DNMT1, whereas unmethylated PSA promoter state in LNCaP was associated with downregulation of DNMT1. These findings highlight distinct methylation patterns in the PSA promoter that differentiate between aggressive, indolent, and benign prostate states. Translating this epigenetic insight into clinical diagnostics could enhance the precision of PSA-based diagnostics, addressing limitations such as false negatives in PSA testing for aggressive PCa. Further exploration of CCWGG methylation’s role in imprinting and monoallelic expression is warranted, particularly in patient-derived samples.

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