In vitro cell transformation induced by synthetic amorphous silica nanoparticles

Abstract

International audienceSynthetic amorphous silica nanoparticles (SAS) are among the most widely produced and used nanomaterials, but little is known about their carcinogenic potential. This study aims to evaluate the ability of four different SAS, two precipitated, NM-200 and NM-201, and two pyrogenic, NM-202 and NM-203, to induce the transformation process. For this, we used the recently developed in vitro Bhas 42 cell transformation assay (CTA). The genome of the transgenic Bhas 42 cells contains several copies of the v-Ha-ras gene, making them particularly sensitive to tumor-promoter agents. The Bhas 42 CTA, which includes an initiation assay and a promotion assay, was validated in our laboratory using known soluble carcinogenic substances. Its suitability for particle-type substances was verified by using quartz Min-U-Sil 5 (Min-U-Sil) and diatomaceous earth (DE) microparticles. As expected given their known transforming properties, Min-U-Sil responded positively in the Bhas 42 CTA and DE responded negatively. Transformation assays were performed with SAS at concentrations ranging from 2 µg/cm 2 to 80 µg/cm 2. Results showed that all SAS have the capacity to induce transformed foci, interestingly only in the promotion assay, suggesting a mode of action similar to tumor-promoter substances. NM-203 exhibited transforming activity at a lower concentration than the other SAS. In conclusion, this study showed for the first time the transforming potential of different SAS, which act as tumor-promoter substances in the Bhas 42 model of cell transformation.Les nanoparticules de silice amorphes de synthèse (SAS) sont les nanomatériaux les plus produits et les plus utilisés dans le monde, mais leur potentiel cancérogène est peu étudié. Cette étude avait pour but d’évaluer la capacité de quatre différentes SAS, deux sous forme précipitée, NM-200 et NM-201 et deux sous forme pyrogénée, NM-202 et NM-203, d’induire des processus de cancérogénèse. Pour cela, nous avons utilisé l’essai de transformation sur les cellules Bhas 42 (Bhas 42 CTA) qui a été récemment développé. Le génome des cellules Bhas 42 transgéniques contient plusieurs copies du gène v-Ha-ras, ce qui leur confère les caractéristiques de cellules « initiées » et les rend particulièrement sensibles aux agents promoteurs de tumeur. Le Bhas 42 CTA, qui inclut un essai d’initiation et un essai de promotion, a été validé dans notre laboratoire en utilisant des agents cancérogènes solubles connus. Son adaptabilité pour des substances de type particule a été vérifié en utilisant des microparticules de quartz Min-U-Sil 5 (Min-U-Sil) et de terre de diatomée (DE). Comme attendu d’après leur propriété transformante connue, le Min-U-Sil a répondu positivement et la DE négativement au Bhas 42 CTA. Les essais de transformation ont été réalisés à des concentrations de SAS s’étalant de 2 µg/cm2 à 80 µg/cm2. Les résultats montrent que toutes les SAS ont la capacité d’induire des foyers de transformation et de manière intéressante, uniquement dans l’essai de promotion, suggérant...

Genotoxicity of Nanomaterials: Advanced In Vitro Models and High Throughput Methods for Human Hazard Assessment—A Review

“…Recent works have, however, shown that cell transformation assays are useful tools to predict carcinogens [ 146 ]. In particular, the CTAs can be useful to identify non-genotoxic carcinogens and should be included as an integral part of a battery of in vitro tests in order to predict carcinogenic potential of chemicals and also NMs [ 147 ]. Fontana et al investigated four different amorphous non-genotoxic silica particles with the CTA and indicated one non-genotoxic carcinogenic out of two pyrogenic and two precipitated silica materials [ 147 ].…”

Genotoxic Impact of Aluminum-containing Nanomaterials in Human Intestinal and Hepatic Cells.

“…This decrease, observed at concentrations inducing a weak inhibition of cell proliferation at Day 7, is likely explained by a more pronounced inhibition of cell growth after 21 days of culture due to the three repeated treatments during the promotion assay. This phenomena was also observed with amorphous silica NMs [49] as well as with other non-carcinogenic chemicals such as Lascorbic acid and caffeine [68]. [24].…”

Predictive early gene signature during mouse Bhas 42 cell transformation induced by synthetic amorphous silica nanoparticles

“…The CTA in promotion condition, originally proposed by the OECD [16], was modified as described previously [8] ( Supplementary Fig. A.1).…”

“…Two long-term carcinogenesis studies with SAS have been published to date, showing that repeated intratracheal instillations of pyrogenic SAS in rats increased the incidence of lung tumors [6,7]. Recently, we showed that precipitated and pyrogenic SAS (NM-200, NM-201 NM-202 and NM-203) induced the transformation of Bhas 42 cells in cell transformation assays (CTA) [8].…”

“…The aim of this study was thus to use transcriptomic analysis to identify an early gene signature for Bhas 42 cell transformation that is shared by an SAS, a crystalline silica and the tumor promoter 12-O-tetradecanoylphorbol-13-acetate (TPA). Based on previous data [8], the transcriptomic procedure was carried out after Bhas 42 cell exposure to the SAS NM-203, which in the previous study induced the highest level of cell transformation. In addition, the crystalline silica Min-U-Sil 5…”