Effect of epigenetic modification of maspin on extravillous trophoblastic function

miR-150-5p mediates extravillous trophoblast cell migration and angiogenesis functions by regulating VEGF and MMP9

INTRODUCTION

miR-150-5p is involved in placenta function. Matrix metalloproteinases (MMPs) play important roles in migration and invasion of cells, while VEGF is the major contributing factor in angiogenesis, and they are related to miR-150-5p. However, the mechanism by which miR-150-5p regulates placental functions is not known. Thus, we investigated the influence of miR-150-5p on extravillous trophoblast function and the underlying epigenetic mechanism.

METHODS

Real-time PCR were used to detect the miR-150-5p in the placenta of patients with preeclampsia and normal pregnant women. HTR-8/SVneo and JEG-3 cells were transfected with miR-150-5p inhibitor. Furthermore, we used CoCl₂ to establish the hypoxia cell model. qRT-PCR and Western blot analysis were performed to detect VEGF and MMP9 expression levels in the transfected cells. Cell Counting Kit-8 assay was conducted to evaluate the proliferation ability. Wound-healing and transwell assays were used to detect the migration and invasion capacities. Tube formation assay was performed to evaluate the angiogenesis ability.

RESULTS

miR-150-5p was up-regulated in the placenta of patients with preeclampsia. Inhibition of miR-150-5p significantly enhanced migration, invasion, and angiogenesis ability of both JEG-3 and HTR-8/SVneo cells. Similar results were seen in the hypoxic HTR-8/SVneo cell model. Moreover, mRNA and protein expression levels of VEGF and MMP9 were upregulated by the inhibition of miR-150-5p.

DISCUSSION

miR-150-5p impacts placental cellular abilities, including migration, invasion, and angiogenesis of extravillous trophoblast cells. More importantly, miR-150-5p regulates VEGF and MMP9 expression. The results suggest that miR-150-5p may have an impact on placenta functions.

Vascular endothelial growth factor C participates in regulation of maspin in extravillous trophoblast cell migration and invasion

Mammary serine protease inhibitor (maspin ; also known as serpin family B member 5 (SERPINB5)) plays a vital role in regulating the biological functions of extravillous trophoblast (EVT) cells, but the mechanism remains unclear. Vascular endothelial growth factor (VEGF ) C is a signature angiogenic molecule expressed and secreted by first-trimester trophoblasts, and bioinformatics analyses has revealed upregulation of VEGFC in pre-eclampsia. The aim of this study was to explore whether maspin regulates EVT cells by regulating the expression of VEGFC . Reverse transcription-polymerase chain reaction and western blotting were used to investigate the effects of hypoxia on the expression of VEGFC in EVT cells. Cells were treated with recombinant (r) maspin and decitabine (to selectively inhibit DNA methyltransferases and then upregulate maspin gene expression), and the effects on VEGFC expression evaluated. In addition, the effects of rVEGFC on the biological functions of EVT cells invitro were evaluated using cell migration and invasion assays. Hypoxia increased the expression of VEGFC in EVT cells. rMaspin upregulated the expression of VEGFC in normoxic EVT cells, and downregulated the expression of VEGFC in hypoxic EVT cells at 24h. Decitabine increased VEGFC expression in normoxic EVT cells, but had no significant effect on VEGFC expression in hypoxic EVT cells. rVEGFC promoted the migration and invasion of normoxic EVT cells and inhibited the invasion of hypoxic EVT cells. These results suggest that VEGFC is involved in the regulation of maspin in EVT cell migration and invasion. However, other molecular mechanisms may be involved and require further investigation.

Maspin impairs the function of endothelial cells: an implying pathway of preeclampsia

Backgroud

Widespread endothelial injury contributes to the occurrence of preeclampsia. Maspin, first identified as a tumor suppressor, plays a critical role in cell invasion and angiogenesis. Our previous studies found that the expression of maspin was increased in preeclampsic placenta. In this research, we studied the function of human umbilical vein endothelial cells (HUVECs) to explore the role and possible mechanism of maspin gene in the pathogenesis of preeclampsia.

Methods

HUVECs were treated with different concentration of recombinant human maspin protein (r-maspin) during normoxia and hypoxia, we detected the proliferation, apoptosis, migration and tube formation of HUVECs. We also assessed nitride oxide (NO) synthesis and the expression of matrix metalloproteinase 2 (MMP2) to further explore the underlying molecular mechanism.

Results

There was only slight maspin expression at mRNA level in HUVECs. Treated HUVECs with r-maspin, the proliferation of HUVECs was significantly promoted both under normoxia and hypoxia. The tubes formed by HUVECs were significantly inhibited and NO synthesis was significantly reduced by r-maspin. Meantime, r-maspin also inhibited MMP2 expression and activity in HUVECs. However, there was no significant change in the migration and apoptosis of HUVECs.

Conclusions

Maspin may be an important participant for mediating endothelial function and ultimately leads to the occurence of preeclamsia.

Decitabine Improves the Clinical Manifestations of Rats With l-NAME-Induced Pre-eclampsia: A Potential Approach to Studying Pre-eclampsia

OBJECTIVE

Pre-eclampsia is a major cause of maternal mortality and morbidity. Conditions with low oxygen tension are regarded as a key factor. Decitabine can partly attenuate the effects of hypoxia. This research was designed to investigate the effects of decitabine in rats with NG-Nitro-L-arginine Methyl Eater (L-NAME) induced pre-eclampsia and to explore the molecular mechanisms.

METHODS

A Wistar rat model of pre-eclampsia was established by intraperitoneal injection of L-NAME, and the intervention reagent was decitabine. Blood pressure (BP) and 24-h urinary protein were monitored. The expression of Mammary Serine Protease Inhibitor (SERPINB5, maspin) in the placenta was detected by reverse transcriptase-polymerase chain reaction (RT-PCR) and western blotting.

RESULTS

Systolic BP in the tail artery of pregnant rats was increased by more than 30 mm Hg, and 24-h urinary protein was significantly increased after L-NAME was added. After decitabine treatment, blood pressure and 24-h urinary protein were significantly decreased. The expression of SERPINB5 in the placenta significantly increased after L-NAME was added. Decitabine significantly elevated the expression of SERPINB5 in the placenta of rats with L-NAME-induced preeclampsia.

CONCLUSION

Decitabine reduced 24-h urinary protein and partly decreased blood pressure of pre-eclampsia in late pregnancy in rats with L-NAME-induced pre-eclampsia and increased the expression of SERPINB5, but the molecular mechanism of decitabine's effect remains unknown. This research provided a potential approach to studying the pathogenesis, treatment and prevention of pre-eclampsia.

Promoter Hypomethylation of Maspin Inhibits Migration and Invasion of Extravillous Trophoblast Cells during Placentation

Objective

Extravillous trophoblast (EVT) cells invade the endometrium and the maternal spiral arterioles during the first trimester. Mammary Serine Protease Inhibitor (Maspin, SERPINB5) plays a putative role in regulating the invasive activity of cytotrophoblasts. The maspin gene is silenced in various cancers by an epigenetic mechanism that involves aberrant cytosine methylation. We investigated the effect of the methylation status of the maspin promoter on the maspin expression and the aggressiveness of EVT cells.

Methods

Western blotting was used to detect the maspin protein expression in EVT cells upon hypoxia. The proliferative ability, the apoptosis rate and the migration and invasiveness were measured with Cell Counting Kit-8 assay, Flow Cytometry technology and Transwell methods. Subsequently, we treated cells with recombinant maspin protein. The methylation degree of maspin promoter region upon hypoxia/ decitabine was detected by bisulfite sequencing PCR and methylation-specific PCR. Finally, we explored the effects of decitabine on maspin protein expression and the aggressiveness of EVT cells.

Results

Hypoxia effectively increased maspin protein expression in EVT cells and significantly inhibited their aggressiveness. The addition of recombinant maspin protein inhibited this aggressiveness. Decitabine reduced the methylation in the maspin promoter region and effectively increased the maspin protein expression, which significantly weakened the migration and invasiveness of EVT cells.

Discussion

The methylation status of the maspin promoter is an important factor that affects the migration and invasion of EVT cells during early pregnancy. A decrease in the methylation status can inhibit the migration and invasion of EVT cells to affect placentation and can result in the ischemia and hypoxia of placenta.

Promoter hypomethylation and increased maspin expression in preeclamptic placentas in a Chinese population

OBJECTIVE

Preeclampsia is thought to begin with shallow trophoblast invasion and inadequate spiral artery remodeling. Maspin, a tumor-suppressor gene, plays a regulatory role in trophoblast invasion and motility. The tissue-specific methylation of the maspin promoter can regulate maspin gene expression in various cancers. We sought to detect maspin gene expression and assess the degrees of methylation of maspin promoter regions in preeclamptic placentas in the Han Chinese population and to investigate the potential role of maspin in the pathophysiology of preeclampsia.

METHODS

We conducted RT-PCR, immunohistochemistry and western blotting to characterize maspin gene expression and protein levels in the placentas from normal and preeclamptic pregnancies. Finally, using methylation-specific PCR and bisulfite sequencing PCR, we detected the degrees of methylation of the promoter regions of maspin in each of the two studied groups.

RESULTS

Maspin expression was increased at the mRNA and protein levels in the preeclamptic placentas compared to the control group. Maspin immunohistochemical staining revealed positive staining in the syncytio-cytotrophoblast layers and more diffuse staining in the preeclamptic group. The mean methylation level of the analyzed promoter region was significantly hypomethylated in the preeclamptic placentas compared to the control placentas, pointing to a negative relationship between maspin promoter methylation and gene expression.

DISCUSSION

Hypomethylation of the maspin promoter results in increased expression of maspin in preeclamptic placentas, which suggests a negative relationship between maspin methylation and maspin expression in this Han Chinese population. Thus, maspin is likely involved in the etiology of preeclampsia.

Placental pseudo-malignancy from a DNA methylation perspective: unanswered questions and future directions

The growing fetus is dependent on adequate placental function for delivery of essential nutrients and oxygen, and for waste removal. The placenta also plays an important protective role; shielding the developing baby from the maternal immune system and adverse environmental exposures. Fundamental to these processes is correct invasion of the decidua and remodeling of maternal vasculature, each of which show remarkable parallels to tumorogenesis, with the obvious exception that the former is usually a tightly controlled process. It is not surprising that these physiological similarities are mirrored in gene expression and epigenetic parallels, many not found in any other aspect of human development. In this perspective, we summarize known DNA methylation similarities between placenta and human tumors, and discuss the implications and knowledge gaps associated with these findings. We also speculate on the potential origin of common DNA methylation features in these two disparate aspects of human physiology.

DNA methyltransferases and TETs in the regulation of differentiation and invasiveness of extra-villous trophoblasts

Specialized cell types of trophoblast cells form the placenta in which each cell type has particular properties of proliferation and invasion. The placenta sustains the growth of the fetus throughout pregnancy and any aberrant trophoblast differentiation or invasion potentially affects the future health of the child and adult. Recently, the field of epigenetics has been applied to understand differentiation of trophoblast lineages and embryonic stem cells (ESC), from fertilization of the oocyte onward. Each trophoblast cell-type has a distinctive epigenetic profile and we will concentrate on the epigenetic mechanism of DNA methyltransferases and TETs that regulate DNA methylation. Environmental factors affecting the mother potentially regulate the DNA methyltransferases in trophoblasts, and so do steroid hormones, cell cycle regulators, such as p53, and cytokines, especially interlukin-1β. There are interesting questions of why trophoblast genomes are globally hypomethylated yet specific genes can be suppressed by hypermethylation (in general, tumor suppressor genes, such as E-cadherin) and how invasive cell-types are liable to have condensed chromatin, as in metastatic cancer cells. Future work will attempt to understand the interactive nature of all epigenetic mechanisms together and their effect on the complex biological system of trophoblast differentiation and invasion in normal as well as pathological conditions.

Assessment of the number and function of macrophages in the placenta of gestational diabetes mellitus patients

In order to assess the number and function of macrophages in the placenta of pregnancy complicated with gestational diabetes mellitus (GDM) as well as those of normal pregnancies, placenta samples were collected from 15 GDM patients (GDM group) and 10 normal pregnant women (control group). The expression levels of macrophage markers (CD68/CD14) and inflammatory cytokines (IL-6/TNF-α) in placenta were detected using immunohistochemistry and PCR. The results showed that the number of CD68+ or CD14+ cells in the GMD group was remarkably higher than that in the control group (P<0.05), indicating that the number of macrophages in the GDM group was significantly greater than that in the control group. The mRNA expression levels of CD68+, IL-6 and TNF-α were higher in the GMD group than in the control group. In conclusion, more macrophages accumulate in placenta of pregnancy complicated with GDM, and the expression levels of pro-inflammation factors are also increased in GDM pregnancies, suggesting that macrophages and inflammatory mediators (IL-6 and TNF-α) may play an important role in GDM.