Search

Air pollution, tobacco smoke, and red meat are associated with renal cell cancer (RCC) risk in the United States and Western Europe; however, the chemicals that form DNA adducts and initiate RCC are mainly unknown. Aristolochia herbaceous plants are used for medicinal purposes in Asia and worldwide. They are a significant risk factor for upper tract urothelial carcinoma (UTUC) and RCC to a lesser extent. The aristolochic acid (AA) 8-methoxy-6-nitrophenanthro-[3,4- d ]-1,3-dioxolo-5-carboxylic acid (AA-I), a component of Aristolochia herbs, contributes to UTUC in Asian cohorts and in Croatia, where AA-I exposure occurs from ingesting contaminated wheat flour. The DNA adduct of AA-I, 7-(2'-deoxyadenosin- N 6 -yl)-aristolactam I, is often detected in patients with UTUC, and its characteristic A:T-to-T:A mutational signature occurs in oncogenes and tumor suppressor genes in AA-associated UTUC. Identifying DNA adducts in the renal parenchyma and pelvis caused by other chemicals is crucial to gaining insights into unknown RCC and UTUC etiologies. We employed untargeted screening with wide-selected ion monitoring tandem mass spectrometry (wide-SIM/MS 2 ) with nanoflow liquid chromatography/Orbitrap mass spectrometry to detect DNA adducts formed in rat kidneys and liver from a mixture of 13 environmental, tobacco, and dietary carcinogens that may contribute to RCC. Twenty DNA adducts were detected. DNA adducts of 3-nitrobenzanthrone (3-NBA), an atmospheric pollutant, and AA-I were the most abundant. The nitrophenanthrene moieties of 3-NBA and AA-I undergo reduction to their N -hydroxy intermediates to form 2'-deoxyguanosine (dG) and 2'-deoxyadenosine (dA) adducts. We also discovered a 2'-deoxycytidine AA-I adduct and dA and dG adducts of 10-methoxy-6-nitro-phenanthro-[3,4- d ]-1,3-dioxolo-5-carboxylic acid (AA-III), an AA-I isomer and minor component of the herbal extract assayed, signifying AA-III is a potent kidney DNA-damaging agent. The roles of AA-III, other nitrophenanthrenes, and nitroarenes in renal DNA damage and human RCC warrant further study. Wide-SIM/MS 2 is a powerful scanning technology in DNA adduct discovery and cancer etiology characterization.

Background: Aristolochic acids (AA) and arsenic are chemical carcinogens associated with urothelial carcinogenesis. Here we investigate the combined effects of AA and arsenic toward the risk of developing upper tract urothelial carcinoma (UTUC)., Methods: Hospital-based ( n = 89) and population-based (2,921 cases and 11,684 controls) Taiwanese UTUC cohorts were used to investigate the association between exposure to AA and/or arsenic and the risk of developing UTUC. In the hospital cohort, AA exposure was evaluated by measuring aristolactam-DNA adducts in the renal cortex and by identifying A>T TP53 mutations in tumors. In the population cohort, AA exposure was determined from prescription health insurance records. Arsenic levels were graded from 0 to 3 based on concentrations in well water and the presence of arseniasis-related diseases., Results: In the hospital cohort, 43, 26, and 20 patients resided in grade 0, 1+2, and 3 arseniasis-endemic areas, respectively. Aristolactam-DNA adducts were present in >90% of these patients, indicating widespread AA exposure. A>T mutations in TP53 were detected in 28%, 44%, and 22% of patients residing in grade 0, 1+2, and 3 arseniasis-endemic areas, respectively. Population studies revealed that individuals who consumed more AA-containing herbs had a higher risk of developing UTUC in both arseniasis-endemic and nonendemic areas. Logistic regression showed an additive effect of AA and arsenic exposure on the risk of developing UTUC., Conclusions: Exposure to both AA and arsenic acts additively to increase the UTUC risk in Taiwan., Impact: This is the first study to investigate the combined effect of AA and arsenic exposure on UTUC., (©2020 American Association for Cancer Research.)

3-Nitrobenzanthrone (3-NBA), a potential human carcinogen, is present in diesel exhaust. The main metabolite of 3-NBA, 3-aminobenzanthrone, was detected in urine of miners occupationally exposed to diesel emissions. Environmental and occupational factors play an important role in development of bladder cancer (BC), one of the most frequent malignancies. It is expected that exposure of urothelium to 3-NBA and its metabolites may induce BC initiation and/or progression. To test this hypothesis, we studied geno- and cytotoxicity of 3-NBA using an in vitro BC model. 3-NBA induced higher levels of DNA adducts, reactive oxygen species and DNA breaks in aggressive T24 cells than in more differentiated RT4 cells. To understand the nature of this difference we examined the role of several enzymes that were identified as 3-NBA bio activators. However, the difference in DNA adduct formation cannot be directly linked to the different activity of any of the examined enzymes. Conversely, the difference of tested cell lines in p53 status can partly explain the distinct levels of 3-NBA-DNA adducts and DNA damage induced by 3-NBA. Therefore, we assume that more aggressive T24 cells are more predisposed for DNA adduct formation, DNA damage and, possibly, mutations and as a result further tumorigenesis., (Copyright © 2016. Published by Elsevier Inc.)