Blood Pyrrole–DNA Adducts Define the Early Tumorigenic Risk in Patients with Pyrrolizidine Alkaloid-Induced Liver Injury
Yisheng He, Wei Zhang, Jiang Ma, Qingsu Xia, Zijing Song, Lin Zhu, Chunyuan Zhang, Jia Liu, Yang Ye, Peter P. Fu, Yuzheng Zhuge, Ge Lin
Abstract
Pyrrolizidine alkaloids (PAs) are among the most common phytotoxins with emerging evidence to contaminate soil, water, and nearby plants. Humans are frequently exposed to PA-contaminated food products or PA-containing herbal remedies. The reactive metabolites of PAs rapidly alkylate DNA to form pyrrole–DNA adducts (PDAs) and seed a population of mutations that initiate tumorigenesis in experimental models. However, the clinical evidence of PA-induced initial DNA damage is absent. This study developed a liquid biopsy approach for detecting PDAs in blood to diagnose PA-induced genotoxicity. Blood DNA samples, extracted from PA-exposed rats, were reacted with silver nitrate to cleave the N-linkage between conjugated DNA bases and pyrrole. The released pyrrole was chemically derivatized to a stable product which was measured by liquid chromatography-tandem mass spectrometry. Using this method, PDAs were, for the first time, detected in blood samples from 18 patients with PA-induced liver injury. Notably, PDAs were detectable in patients’ blood samples collected one month after hospital admission, indicating adequate persistence of PDAs for use as a clinical biomarker of PA-induced genotoxicity. Our findings provide clinical indication of PA-induced genotoxicity, which warrants early detection of PDAs as an actionable approach for prevention of PA-associated carcinogenesis.