Background
Exposure to arsenic can damage trophoblast cells and thus induce abortion, but the mechanism is not known.
Objective
To investigate the role of miR-145 and PTEN/AKT/mTOR pathway in arsenic-induced abortion and trophoblast cell damage in rats.
Methods
In the animal experiment, twenty SD pregnant rats were randomly divided into a normal control group (saline gavage) and an arsenic-induced abortion group (10.65 mg·kg−1 sodium arsenite solution was administered by gavage, and the gavage volume was 10 mL·kg−1), with 10 rats in each group. After the miscarriage occurred in the arsenic-induced abortion group (5-6 d after exposure), placental tissues were collected from the two groups. The mRNA expression levels of microRNA-145 (miR-145), phosphatase and tensin homologue (PTEN), kinase B (AKT), mammalian target of rapamycin (mTOR) were detected by real-time quantitative PCR (RT-PCR), and the protein expression levels of PTEN, AKT, mTOR, p-AKT, and p-mTOR were detected by Western blotting. For the in vitro study with immortalized human trophoblast cell line (HTR-8/SVneo cells), a control group, an arsenic exposure group, an miR-145 overexpression group, and an arsenic exposure+miR-145 overexpression group were prepared and cultured for 72 h with 37 °C and 5% CO2, at cell density of 5×105 cells per well, and the arsenic exposure concentration was 20 μmol·L−1. The MTT method was applied to detect cell viability, crystal violet staining to detect the number of monoclonal formation, flow cytometry to detect the level of apoptosis, Image J Angiogenesis Analyzer 1.8.0 plug-in to evaluate total blood vessel length and total blood vessel number; the detection indexes and methods of genes and proteins were the same as "animal experiment".
Results
(1) In the animal experiment, compared with the normal control group, the expression level of miR-145 mRNA in the placenta tissues of the arsenic-induced abortion group was increased (P<0.05), and the expression levels ofPTEN, AKT, mTOR mRNA and proteins, and p-AKT and p-mTOR proteins were decreased (P<0.05). (2) For thein vitro study, compared with the control group, the cell viability rate, number of monoclonal formation, total vessel length, and total vessel number were decreased, and the apoptosis rate was increased in the arsenic exposure group, the miR-145 overexpression group, and the arsenic exposure+miR-145 overexpression group (P<0.05). Compared with the arsenic exposure group and the miR-145 overexpression group, the cell viability rate, number of monoclonal formation, total vessel length, and vessel number were decreased, and the apoptosis rate was increased in the arsenic exposure+miR-145 overexpression group (P<0.05). Compared with the control group, the levels ofmiR-145 mRNA in the arsenic exposure group, the miR-145 overexpression group, and the arsenic exposure+miR-145 overexpression group increased (P<0.05), the expression levels ofPTEN, AKT, mTOR mRNA and protein and the expression levels of p-AKT and p-mTOR protein were decreased (P<0.05); compared with the arsenic exposure group and the miR-145 overexpression group, the level ofmiR-145 mRNA in the arsenic exposure+miR-145 overexpression group was increased (P<0.05), and the levels ofPTEN, AKT, mTOR mRNA and protein as well as p-AKT and p-mTOR protein were decreased (P<0.05).
Conclusion
miR-145 might be related to abortion due to arsenic exposure. miR-145 could inhibit the proliferation and angiogenesis of trophoblast HTR-8/SVNEO cells, and promotes their apoptosis; the mechanism may be related to the inhibition of PTEN/AKT/mTOR pathway.
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