Pravastatin inhibits microRNA-155 expression and improves functions of lipopolysaccharide-treated human extravillous trophoblast cells

Objective To investigate the effects of pravastatin on the expression of microRNA-155 (miR-155) and the functions of lipopolysaccharide (LPS)-treated extravillous trophoblast cells. Methods In vitro cultured HTR-8/SVneo cells were divided into the following groups: control group, enhanced plasmid with green fluoscent protein (pEGFP)-miR-155 group (transfected with green fluorescent protein-tagged miR-155), LPS group (treated with 100 ng/mL of LPS), miR-155 inhibitor+LPS group, pravastatin+LPS group (treated with 100 ng/mL of LPS following pretreatment with 12.50, 25.00, 50.00 and 100.00 μg/ml of pravastatin), and pravastatin+pEGFP-miR-155 group (transfected with pEGFP-miR-155 following pretreatment with 50 μg/ml of pravastatin). Levels of miR-155 in HTR-8/SVneo cells treated with different strategies were measured by real-time polymerase chain reaction. Expression of phosphorylated JunB (p-JunB) and p-FosB proteins was analyzed by Western blotting. Migration, invasion and apoptosis of HTR-8/SVneo cells were also analyzed. All data were analyzed with t test. Results (1) Compared with the control group, HTR-8/SVneo cells in the pEGFP-miR-155 group were characterized by shorter migration distance [(274.70±18.82) vs (181.00±8.62) μm], less transmembrane cells [(123.00±4.36) vs (63.00±6.08)] and enhanced apoptosis [(5.40±0.68)% vs (9.27±0.68)%] (all P<0.05). (2) Compared with the LPS group, the miR-155 inhibitor+LPS group showed longer migration distance of HTR-8/SVneo cells [(166.30±5.07) vs (242.00±18.07) μm, P<0.05], more transmembrane cells [(71.67±6.12) vs (109.00±7.81), P<0.05] and decreased cell apoptosis [(14.40±1.69)% vs (6.23±0.44)%, P<0.05]. (3) Expression of miR-155 at mRNA level in the LPS group was increased as compared with that of the control group (1.65±0.07 vs 0.79±0.12, P<0.05). Compared with the LPS group, pretreatment with 12.50, 25.00, 50.00 and 100.00 μg/ml of pravastatin decreased the expression of miR-155 at mRNA level [(1.14±0.10), (1.02±0.10), (0.74±0.15) and (1.14±0.02)], especially at the concentration of 50 μg/ml (all P<0.05). (4) Expression of p-JunB and p-FosB proteins in the control, LPS and pravastatin (50 μg/ml)+LPS groups were (0.33±0.06) vs (0.37±0.07), (1.22±0.20) vs (0.80±0.13), and (0.31±0.02) vs (0.21±0.05), respectively, showing higher expression level in both p-JunB and p-FosB proteins in the LPS group compared with that of the other two groups (all P<0.05). (5) Compared with the LPS group, the pravastatin (50 μg/ml)+LPS group showed increased migration distance [(166.30±5.07) vs (246.80±13.42) μm, P<0.05], increased numbers of transmembrane cells [(71.67±6.12) vs (95.33±2.73), P<0.05] and decreased cell apoptosis [(14.40±1.69) vs (6.05±0.35)%, P<0.05]. (6) Compared with the pEGFP-miR-155 group, the pravastatin (50.00.00 μg/mL)+pEGFP-miR-155 group showed longer migration distance [(197.50±13.86) vs (275.80±13.63) μm, P<0.05], more transmembrane cells [(52.67±5.49) vs (125.00±6.66), P<0.05] and lower rate of cell apoptosis [(8.90±1.00) vs (5.05±0.35)%, P<0.05]. Conclusions Pretreatment of extravillous trophoblast cells with pravastatin can protect them from apoptosis and loss of migratory and invasive abilities through inhibiting the activation of AP-1 and down-regulating the expression of miR-155, which may be a mechanism that inhibits the development of preeclampsia. Key words: Pravastatin; Preeclampsia; Trophoblast; microRNAs; Cell movement