Abstract 4252: New molecular evidence associating exposure to aristolochic acid with urothelial cancers in South Korean patients: Implications for global public health risk linked to carcinogenic herbal medicines

Abstract

Abstract Aristolochic acid (AA) is a potent nephrotoxin and carcinogen (IARC Group 1) associated with urothelial, hepatobiliary, and renal carcinomas. Exposure to AA from dietary intake of traditional herbal medicines containing Aristolochia species poses a global health hazard, yet also an opportunity for disease prevention. Molecular epidemiology studies employing sensitive and specific biomarkers for screening of populations at risk are thus warranted. Genome-scale studies established a characteristic mutational signature of AA. Exploiting its unique features (predominant A>T transversions), alongside the knowledge of key affected cancer genes, we devised a cost-effective targeted resequencing (TRseq) method to detect AA etiology in upper tract urothelial carcinoma (UTUC) samples from South Korean patients. Aristolochia species (e.g., A. contorta, Bunge) are included in the Korean traditional pharmacopoeia although the local occurrence of AA-associated cancers remains unexplored. DNA from archived, paired kidney and UTUC samples of 16 Korean patients was used for adduct and TRseq analyses. Thirty-one cancer genes, previously found recurrently mutated in AA-induced UTUCs from Asia and Europe, were selectively captured using SeqCap EZ enrichment kit (Nimblegen Roche) and sequenced using Illumina MiSeq. Sets of UTUCs from Croatia (harboring AA signature) and from US patients (unlikely to be exposed) were included as respective positive and negative controls. Somatic variants were called against the patient-matched non-tumor DNA, using two distinct variant calling strategies. Three out of 16 kidney cortex samples tested positive for aristolactam-dA (AL-dA) adducts, indicative of past exposure to AA. One UTUC sample with A>T-mutated TP53 harbored 32 A>T mutations across the 31-gene panel, and another 8 cases, 3 of which were adduct-positive, harbored lower counts of A>T mutations (up to 3 per gene panel per sample). The allelic frequencies of the considered A>T mutations ranged between 10-83%. The positive control samples exhibited a strong A>T signal while the US samples were all A>T-negative, as expected. We propose that the TRseq approach can detect AA-driven mutagenesis in UTUC tumors, providing a sensitive complement to the AL-dA adduct analysis, at low per-sample cost. Importantly, the presence of adducts and AA signature mutations in South Korean UTUC cases highlights a previously uncharacterized population at risk. The future use of TRseq, either alone or in combination with adduct analysis, can address exposure to AA in extended UTUC case series, thereby assisting in the design of preventive measures against this global public health hazard. Funding: IARC; SW is Recipient of research support from the Drs. Martin & Dorothy Spatz Charitable Foundation; Henry and Marsha Laufer grant to KGD, VSS, APG. Citation Format: Shuhan Wang, Daeeun Choi, Jaesung Lim, Kathleen G. Dickman, Magali Olivier, Stephanie Villar, Viktoriya S. Sidorenko, Maude Ardin, Byeong H. Yun, Robert J. Turesky, Minho Shong, Jiri Zavadil, Arthur P. Grollman. New molecular evidence associating exposure to aristolochic acid with urothelial cancers in South Korean patients: Implications for global public health risk linked to carcinogenic herbal medicines [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 4252. doi:10.1158/1538-7445.AM2017-4252