Functional effects of differentially expressed microRNAs in A549 cells exposed to MWCNT-7 or crocidolite

Multi-walled carbon nanotubes (MWCNT) are engineered nanomaterials widely used in industrial and biomedical applications. Yet, MWCNT inhalation may induce pulmonary adverse effects, and the MWCNT-7 (Mitsui-7) has been classified as possibly carcinogenic to humans. However, its molecular mechanisms of action are poorly understood and there are no biomarkers of exposure for occupational monitoring. Several pulmonary diseases, including lung cancer, have been associated with alterations in microRNA expression that are used as biomarkers of disease progression, and differentially-expressed microRNAs (DE miRNAs) can also allow understanding the molecular effects induced by a toxicant. In this study, we identify DE miRNAs in A549 alveolar epithelial cells following 24 h exposure to MWCNT-7 or crocidolite, as well as their enriched cellular functional pathways. These indicate that both materials change cell survival, differentiation and proliferative properties under the influence of AMPK, FoxO, TGF-β and Hippo pathways, and their metabolic activity and cell-to-cell communication. In addition, MWCNT-7 affects the actin cytoskeleton, ubiquitin mediated proteolysis, and ECM-receptor interactions; crocidolite the PI3K-Akt and mTOR pathways, endocytosis, and central carbon metabolism. Since deregulation of these pathways may be related to carcinogenesis, an interaction network of DE miRNAs and corresponding target cancer-related genes was constructed, highlighting the carcinogenic potential of Mitsui-7. Highlights: Multi-walled carbon nanotubes (MWCNT) are nanomaterials widely used that may induce pulmonary adverse effects upon inhalation; A profile of differentially expressed (DE) miRNAs in A549 alveolar cells was identified following exposure to MWCNT-7 and crocidolite using NGS; Both materials change AMPK, FoxO, TGF-β and Hippo pathways, the cell metabolic activity and cell-to-cell communication; MWCNT-7 affects the actin cytoskeleton, ubiquitin mediated proteolysis, and ECM-receptor interactions; Crocidolite affects the PI3K-Akt and mTOR pathways, endocytosis, and central carbon metabolism; An interaction network of DE miRNAs and corresponding target cancer-related genes highlighted the carcinogenic potential of MWCNT-7, even at low dose and short-term exposure. This work was funded by FCT/MCTES, Project ToxApp4NanoCELFI (PTDC/SAU-PUB/32587/2017) through national funds (PIDDAC) and ToxOmics (UID/BIM/00009/2013). It is also a result of the GenomePT project (POCI-01-0145-FEDER-022184), supported by COMPETE 2020 - Operational Programme for Competitiveness and Internationalisation (POCI), Lisboa Portugal Regional Operational Programme (Lisboa2020), Algarve Portugal Regional Operational Programme (CRESC Algarve2020), under the PORTUGAL 2020 Partnership Agreement, through the European Regional Development Fund (ERDF), and by FCT. info:eu-repo/semantics/publishedVersion