miR221 regulates cell migration by targeting annexin a1 expression in human mesothelial MeT-5A cells neoplastic-like transformed by multi-walled carbon nanotube

Background: Multi-walled carbon nanotube (MWCNT) is one of the most widely used manufactured nanomaterials, however, its potential harmful effect on human health is of great concern. Previously we have shown the acute and chronic exposure to MWCNT induced different responses in human mesothelial MeT-5A cells. In the current study, MeT-5A cells were continuously subjected to MWCNT exposure at 10 mu g/cm(2) for 48 h per passage, up to a whole year, to further clarify the carcinogesis and its potential mechanisms of MWCNT. Results: After one-year MWCNT treatment, MeT-5A cells exhibited neoplastic-like properties, including morphological changes, anchorage-independent growth, increased cell proliferation and cell migration. Further examination revealed the expression of microRNA 221 (miR221) was gradually decreased, while the annexin a1 expression was increased at both the mRNA and protein level during the exposure. Bioinformatic analysis indicated that annexin a1 is a target for miR221 regulation, and it was confirmed by transfecting cells with miR221 mimics, which resulted in the downregulation of annexin a1. Detailed analyses demonstrated miR221 was involved in the regulation of cell migration, e.g., downregulation of miR221 or overexpression of ANNEXIN A1, contributed to the increased cell migration. In contrast, overexpression of miR221 or downregulation of ANNEXIN A1 slowed cell migration. Conclusions: Taken together, these results point to a neoplastic-transforming property of MWCNT, and the miR221-annexin a1 axis is involved in the regulation of cell migration in the transformed cells.