Evaluating the mutagenicity of N-nitrosodimethylamine in 2D and 3D HepaRG cell cultures using error-corrected next generation sequencing.

Human liver-derived metabolically competent HepaRG cells have been successfully employed in both two-dimensional (2D) and 3D spheroid formats for performing the comet assay and micronucleus (MN) assay. In the present study, we have investigated expanding the genotoxicity endpoints evaluated in HepaRG cells by detecting mutagenesis using two error-corrected next generation sequencing (ecNGS) technologies, Duplex Sequencing (DS) and High-Fidelity (HiFi) Sequencing. Both HepaRG 2D cells and 3D spheroids were exposed for 72 h to N-nitrosodimethylamine (NDMA), followed by an additional incubation for the fixation of induced mutations. NDMA-induced DNA damage, chromosomal damage, and mutagenesis were determined using the comet assay, MN assay, and ecNGS, respectively. The 72-h treatment with NDMA resulted in concentration-dependent increases in cytotoxicity, DNA damage, MN formation, and mutation frequency in both 2D and 3D cultures, with greater responses observed in the 3D spheroids compared to 2D cells. The mutational spectrum analysis showed that NDMA induced predominantly A:T → G:C transitions, along with a lower frequency of G:C → A:T transitions, and exhibited a different trinucleotide signature relative to the negative control. These results demonstrate that the HepaRG 2D cells and 3D spheroid models can be used for mutagenesis assessment using both DS and HiFi Sequencing, with the caveat that severe cytotoxic concentrations should be avoided when conducting DS. With further validation, the HepaRG 2D/3D system may become a powerful human-based metabolically competent platform for genotoxicity testing.

Erythrocyte PIG-A mutant frequencies in cancer patients receiving cisplatin.

BACKGROUND: Cisplatin is a primary chemotherapy choice for various solid tumors. DNA damage caused by cisplatin results in apoptosis of tumor cells. Cisplatin-induced DNA damage, however, may also result in mutations in normal cells and the initiation of secondary malignancies. In the current study, we have used the erythrocyte PIG-A assay to evaluate mutagenesis in non-tumor hematopoietic tissue of cancer patients receiving cisplatin chemotherapy. METHODS: Twenty-one head and neck cancer patients undergoing treatment with cisplatin were monitored for the presence of PIG-A mutant total erythrocytes and the young erythrocytes, reticulocytes (RETs), in peripheral blood for up to five and a half months from the initiation of the anti-neoplastic chemotherapy. RESULTS: PIG-A mutant frequency (MF) in RETs increased at least two-fold in 15 patients at some point of the monitoring, while the frequency of total mutant RBCs increased at least two-fold in 6 patients. A general trend for an increase in the frequency of mutant RETs and total mutant RBCs was observed in 19 and 18 patients, respectively. Only in one patient did both RET and total RBC PIG-A MFs did not increase at any time-point over the monitoring period. CONCLUSION: Cisplatin chemotherapy induces moderate increases in the frequency of PIG-A mutant erythrocytes in head and neck cancer patients. Mutagenicity measured with the flow cytometric PIG-A assay may serve as a tool for predicting adverse outcomes of genotoxic antineoplastic therapy.