Effects of forkhead box protein M1 on trophoblast invasion and its role in preeclampsia development

Abstract

The present study aimed to investigate the expression of the forkhead box protein M1 (FOXM1) in the placenta of patients with preeclampsia, and its effect on trophoblasts. A total of 28 patients with preeclampsia and 30 patients without preeclampsia (controls) who underwent cesarean section and were admitted to the Affiliated Hospital of Qingdao University between June 2013 and September 2016 were enrolled in the present study. The expression of FOXM1 in placental tissues was examined by reverse transcription-quantitative polymerase chain reaction, western blotting and immunohistochemistry. HTR8/SVneo cells were used to measure the in vitro expression of the vascular endothelial growth factor (VEGF). The results demonstrated that FOXM1 expression was downregulated in the placental tissues of patient with preeclampsia (P<0.05). Following the silencing of FOXM1 expression, the proliferation of HTR8/SVneo cells was suppressed. The results of flow cytometry demonstrated that proportion of HTR8/SVneo cells in the G0/G1 phase and the proportion of apoptotic cells increased. The expression of the apoptosis regulator BCL-2, as well as the expression of VEGF mRNA and protein expression were also downregulated following FOXM1 silencing. FOXM1 may therefore promote the development of preeclampsia via the VEGF signaling pathway.

Keywords: forkhead box protein M1; preeclampsia; trophoblast; vascular endothelial growth factor.

Figure 1.

FOXM1 expression is decreased in the placentas of patients with PE. The expression of FOXM1 (A) mRNA and (B) protein was decreased in PE placenta compared with normal placenta. (C) Immunohistochemical staining of FOXM1 expression in placental tissues. *P<0.05 vs. normal placenta. PE, preeclampsia; FOXM1, forkhead box protein M1. Tamhane's T2 was used for statistical analysis.

Figure 2.

FOXM1 silencing decreases the proliferation of trophoblasts. FOXM1 (A) mRNA and (B) protein expression in HTR8/SVneo cells following transfection with siFOXM1. (C) MTT assay measuring the proliferation of HTR8/SVneo cells following transfection with siFOXM1 or NC. *P<0.05 and **P<0.01 vs. NC. NC, negative control; FOXM1, forkhead box protein M1; si, small interfering RNA; OD, optical density. Student-Newman-Keuls method was used for statistical analysis.

Figure 3.

FOXM1 silencing increases the proportion of cells in the G0/G1 phase. (A) Cell cycle distribution and (B) quantification of cell cycle distribution of HTR8/Svneo cells following FOXM1 siRNA transfection. *P<0.05 vs. NC. NC, negative control; FOXM1, forkhead box protein M1; si, small interfering. Student-Newman-Keuls method was used for statistical analysis.

Figure 4.

FOXM1 silencing increases the proportion of apoptotic cells and decreases BCL-2 protein expression. (A) Flow cytometric analysis identifying the (B) proportion of apoptotic cells in HTR8/SVneo cells following transfection with FOXM1 siRNA. (C) BCL-2 protein expression in transfected cells. *P<0.05 and **P<0.01 vs. NC. NC, negative control; FOXM1, forkhead box protein M1; si, small interfering RNA; BCL-2, apoptosis regulator BCL-2; PI, propidium iodide. Student-Newman-Keuls method was used for statistical analysis.

Figure 5.

FOXM1 silencing decreases VEGF expression. The expression of VEGF (A) mRNA and (B) protein was decreased in HTR8/SVneo cells following transfection with FOXM1 siRNA. *P<0.05 vs. NC. NC, negative control; FOXM1, forkhead box protein M1; si, small interfering RNA; VEGF, vascular endothelial growth factor. Student-Newman-Keuls method was used for statistical analysis.