Aristolochic acid (AA) causes
aristolochic acid nephropathy (AAN), first described in women in Belgium accidently prescribed Aristolochia fangchi in a slimming treatment, and also
Balkan endemic nephropathy (BEN), through probable dietary contamination with Aristolochia clematitis seeds. Both nephropathies have a high risk of urothelial
cancer, with AA being the causative agent. In tissues of AAN and BEN patients, a distinct
DNA adduct, 7-(deoxyadenosin-N6-yl)-aristolactam I (dA-AAI), has been detected.
DNA adducts can be removed through DNA repair, they can result in mutations through erroneous DNA replication or they can cause cell death. The dA-AAI adduct induces AT to TA transversions in the
tumor-suppressor TP53 gene in experimental systems, matching TP53 mutations observed in urothelial
tumors from AAN
cancer cases. Using thin-layer chromatography 32P-postlabeling and mass spectrometric analysis we report the detection of dA-AAI in renal
DNA from 11 Belgian AAN patients over 20 years after exposure to AA had ceased. Our results showed that dA-AAI is an established
biomarker of AA exposure, and that this
biomarker can be demonstrated to be persistent decades after a distinct AA exposure. Further, the persistence of dA-AAI adducts appears to be a critical determinant for the AA mutational fingerprint frequently found in oncogenes and tumor suppressor genes recently identified by whole genome sequencing of AA-associated urothelial
tumors. The potential for exposure to AA worldwide is high; the unprecedented long-term persistence of dA-AAI provides a useful long-term
biomarker of exposure and attests to the role of AA in human urothelial
malignancy.