Expression Pattern of the CCAAT/Enhancer-Binding Protein C/EBP-β in Gestational Trophoblastic Disease

Oxidative stress-induced C/EBPβ inhibits β-catenin signaling molecule involving in the pathology of preeclampsia

INTRODUCTION

Oxidative stress-induced trophoblast cell dysfunction is a major pathology in preeclampsia (PE). Recently, CCAAT/enhancer binding protein beta (C/EBPβ) has been investigated as a tumor suppressor that participates in tumor invasion. However, the function of C/EBPβ in trophoblast cells remains unknown. Our study was designed to detect the expression of C/EBPβ in the preeclamptic placenta and to identify the underlying mechanisms of oxidative stress.

METHODS

Human placental tissues with PE were collected. The expression of C/EBPβ and β-catenin were detected. Human first trimester extravillous trophoblast cell (HTR8/SVneo) line exposed to hypoxia/reoxygenation (H/R) was employed as an oxidative stress model in vitro to investigate the effects of C/EBPβ on invasion and the expression of β-catenin. Moreover, first trimester-derived placental villous explants were used to verify the effects of C/EBPβ and β-catenin in placentation.

RESULTS

In preeclamptic placentas, C/EBPβ was overexpressed and β-catenin was decreased. In addition, C/EBPβ was found to have increased expression in H/R-treated HTR8/SVneo cells and villous explants. C/EBPβ knockdown and β-catenin activation could significantly promote the invasion of HTR8/SVneo cells, enhance the outgrowth and migration in villous explants and inhibit the excessive generation of intracellular ROS. These findings might be related to the increased activities of MMP-2/9 and the decreased expression of TIMP-1/2. Meanwhile, C/EBPβ knockdown remarkably increased the expression of β-catenin.

DISCUSSION

We hypothesize that the oxidative stress-induced overexpression of C/EBPβ might influence the activity of MMPs by regulating the Wnt/β-catenin signaling pathway to affect the invasion of trophoblast cells, which then participate in the pathogenesis of preeclampsia.

CCAAT-enhancer-binding protein β (C/EBPβ) and downstream human placental growth hormone genes are targets for dysregulation in pregnancies complicated by maternal obesity

Human chorionic somatomammotropin (CS) and placental growth hormone variant (GH-V) act as metabolic adaptors in response to maternal insulin resistance, which occurs in "normal" pregnancy. Maternal obesity can exacerbate this "resistance," suggesting that CS, GH-V, or transcription factors that regulate their production might be targets. The human CS genes, hCS-A and hCS-B, flank the GH-V gene. A significant decrease in pre-term placental CS/GH-V RNA levels was observed in transgenic mice containing the CS/GH-V genes in a model of high fat diet (HFD)-induced maternal obesity. Similarly, a decrease in CS/GH-V RNA levels was detected in term placentas from obese (body mass index (BMI) ≥ 35 kg/m(2)) versus lean (BMI 20-25 kg/m(2)) women. A specific decrease in transcription factor CCAAT-enhancer-binding protein β (C/EBPβ) RNA levels was also seen with obesity; C/EBPβ is required for mouse placenta development and is expressed, like CS and GH-V, in syncytiotrophoblasts. Binding of C/EBPβ to the CS gene downstream enhancer regions, which by virtue of their position distally flank the GH-V gene, was reduced in placenta chromatin from mice on a HFD and in obese women; a corresponding decrease in RNA polymerase II associated with CS/GH-V promoters was also observed. Detection of decreased endogenous CS/GH-V RNA levels in human placental tumor cells treated with C/EBPβ siRNA is consistent with a direct effect. These data provide evidence for CS/GH-V dysregulation in acute HFD-induced obesity in mouse pregnancy and chronic obesity in human pregnancy and implicate C/EBPβ, a factor associated with CS regulation and placental development.

Impact of p53 immunostaining in predicting advanced or recurrent placental site trophoblastic tumors: a study of 12 cases

OBJECTIVES

To identify an indicator that can predict tumor cell spread beyond the uterine corpus.

METHODS

We studied clinicopathology and immunohistochemistry of 12 cases of PSTT. Two cases of epithelioid trophoblastic tumor (ETT) were included as reference cases. For immunohistochemistry, antibodies against Ki-67, p53, human chorionic gonadotropin (hCG), human placental lactogen (hPL), carcinoembryonic antigen (CEA, polyclonal antibodies; pCEA), carcinoembryonic antigen-related cellular adhesion molecule 1 (CEACAM1), and bcl-2 were used. PSTT cases were divided as confined and non-confined groups (CG and NCG, respectively). CG consisted of stage I cases with no evidence of recurrence during the follow-up, while NCG consisted of either advanced (stage II or higher) or recurrent stage I lesions.

RESULTS

Age, the interval from the latest pregnancy, serum hCG/hPL levels, tumor size, mitotic figures, Ki-67 labeling indices, and bcl-2 did not discriminate NCG from CG. CEACAM1 and CEA-related antigens as determined by polyclonal anti-CEA antibodies were specifically stained in PSTT cells, but they could not discriminate groups. p53 was positive in PSTT cells in NCG (6/6, 100%), while it was positive in only one case of CG (1/6, 16.7%), indicating a possible usefulness of p53 immunostaining in predicting an invasive or recurrent propensity of PSTT cells (p=0.015).

CONCLUSIONS

This finding also suggests the importance of p53 function in the biology of PSTT cells.