P,p′-Dichlorodiphenyltrichloroethane (p,p′-DDT) and p,p′-dichlorodiphenyldichloroethylene (p,p′-DDE) repress prostate specific antigen levels in human prostate cancer cell lines

Abstract

Despite stringent restrictions on their use by many countries since the 1970s, the endocrine disrupting chemicals, DDT and DDE are still ubiquitous in the environment. However, little attention has been directed to p,p′-DDT and the anti-androgen, p,p′-DDE on androgen receptor (AR) target gene transcription in human cells. Inhibitors of androgenic activity may have a deleterious clinical outcome in prostate cancer screens and progression, therefore we determined whether environmentally relevant concentrations of p,p′-DDT and p,p′-DDE negatively impact AR-regulated expression of prostate-specific antigen (PSA), and other AR target genes in human LNCaP and VCaP prostate cancer cells. Quantitative real-time PCR and immuno-blotting techniques were used to measure intracellular PSA, PSMA and AR mRNA and protein levels. We have shown for the first time that p,p′-DDT and p,p′-DDE repressed R1881-inducible PSA mRNA and protein levels in a dose-dependent manner. Additionally, we used the fully automated COBAS PSA detection system to determine that extracellular PSA levels were also significantly repressed. These chemicals achieve this by blocking the recruitment of AR to the PSA promoter region at 10μM, as demonstrated by the chromatin immunoprecipitation (ChIP) in LNCaP cells. Both p,p′-DDT and p,p′-DDE repressed R1881-inducible AR protein accumulation at 10μM. Thus, we conclude that men who have been exposed to either DDT or DDE may produce a false-negative PSA test when screening for prostate cancer, resulting in an inaccurate clinical diagnosis. More importantly, prolonged exposure to these anti-androgens may mimic androgen ablation therapy in individuals with prostate cancer, thus exacerbating the condition by inadvertently forcing adaptation to this stress early in the disease.