Effects of endocrine disrupting substance on estrogen receptor gene transcription in dialysis patients.

Bisphenol A (BPA) and phthalate diesters, two well-described endocrine-disrupting substances (EDSs), were shown to elute out of the dialysis tubing used by patients who underwent hemodialysis (HD) and peritoneal dialysis (PD). Since these patients require dialysis for survival, they may be exposed to potentially harmful levels of these compounds. In this study, serum BPA levels were quantified in HD (n = 45) and PD (n = 43) patients, and healthy controls (n = 12) using an enzyme-linked immunosorbent assay (ELISA) kit. Our results showed that serum BPA levels were significantly elevated in both HD (5.3 +/- 0.3 ng/mL) and PD (3.8 +/- 0.2 ng/mL) patients compared to controls (2.6 +/- 0.1 ng/mL; P < 0.05); levels in the HD patients were significantly greater than in the PD patients (P < 0.05). To investigate the potential effects of these higher serum BPA levels, the patients' serum samples were examined for their effects on estrogen receptor gene transcription levels using a luciferase assay system. MCF-7 cells that were transfected with estrogen response element (ERE) cDNA were cultured with our patients' sera or a solution of BPA. Our results showed that our patients' sera induced higher levels of ERE transcription than did the same dose of BPA; this higher expression may have been due to the presence of other EDSs in the dialysis patients, such as phthalate diesters (DEHP), though this remains to be determined.