Assessment of Pig‐a, Micronucleus, and Comet Assay Endpoints in Tg.RasH2 Mice Carcinogenicity Study of Aristolochic Acid I

Abstract

A newly developed in vivo Pig‐a gene mutation assay displays great potential for integration into genotoxicity tests. To obtain more evidence for application of the Pig‐a assay, we integrated this assay, micronucleus test in peripheral blood (MN‐pb test) and bone marrow (MN‐bm test), as well as a Comet assay into a transgenic RasH2 mice carcinogenicity study. Fourteen male RasH2 mice and five wild‐type (WT) mice were treated with a strong mutagen aristolochic acid I at a dose of 5 mg/kg/day for 4 consecutive weeks. Mice recovered in 5 weeks. Peripheral bloods were collected for Pig‐a assay, MN‐pb test, and Comet assay at several time points, while bone marrow and target organs were harvested for the MN‐bm test and pathological diagnosis after mice were euthanized. Finally, 13 of the 14 RasH2 mice developed squamous cell carcinomas in the forestomach, while there were no carcinomas in the WT mice. Pig‐a mutant frequencies (MFs) consecutively increased throughout the study to a maximum value of approximately 63‐fold more than background. These frequencies were relative to the incidence, size, and malignant degree of tumors. Micronucleated reticulocytes increased from Day 1 to Day 49, before returning to background levels. No positive responses were observed in either the MN‐bm test or the Comet assay. Results suggested that, when compared with the other two tests, the Pig‐a assay persistently contributed to sustaining MFs, enhanced detection sensitivity due to the accumulation of Pig‐a mutations, and demonstrated better predictability for tumorigenicity. Environ. Mol. Mutagen. 61:266–275, 2020. © 2019 Wiley Periodicals, Inc.

Evaluación in vivo del efecto genotóxico y citotóxico de los extractos acuosos de dos variedades mutantes de Hibiscus sabdariffa L.

“…Las evaluaciones de genotoxicidad se realizan en varios agentes, para determinar su inocuidad, como fármacos [24], extractos de especies agronómicas como el Allium sp. [25], principios activos de plantas [16] o extractos de plantas de uso medicinal [14]. No se ha encontrado en la literatura especializada evaluaciones de los efectos secundarios de variedades mutantes de plantas medicinales.…”

“…Las plantas de uso medicinal deben ser evaluadas en sus posibles efectos secundarios para establecer su inocuidad o su potencial de genotoxicidad [13,14]. Los efectos secundarios de agentes químicos o físicos se pueden evaluar por la técnica de análisis de micronúcleos [15], donde se evalúa la pérdida del material genético por ruptura en el cromosoma (efecto clastogénico) o pérdida de un cromosoma entero (efecto aneugénico), los cuales quedan rezagados en el citoplasma y pueden ser visualizados en una evaluación por microscopía de inmersión; es rápida y relativamente de bajo costo [16,17]. En el ensayo de variaciones en las frecuencias de células micronucleadas (MNs) para evaluar el potencial genotóxico, donde se comparan las frecuencias de micronúcleos en las muestras tratadas con las testigo y se evalúan su significancia.…”

Food-Borne Chemical Carcinogens and the Evidence for Human Cancer Risk

“…Genotoxicity/DNA Binding (Adducts): AAI and AAII, have been found to be genotoxic in vitro and in vivo [ 141 , 145 , 146 ] and to form DNA adducts in vitro and in rodent tissues [ 141 , 147 , 148 , 149 , 150 , 151 ], as well as in humans urothelial tissues of patients with Chinese herb nephropathy, Balkan endemic nephropathy or urothelial cancer [ 152 , 153 ]. The major AA-specific DNA adducts were 7-(deoxyadenosin- N 6-yl)aristolactam and 7-(deoxyguanosin- N 2-yl)aristolactam [ 141 ].…”