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Placental insufficiency disorders, including preeclampsia and intrauterine growth restriction, are major obstetric complications that can have devastating effects on both the mother and the fetus. These syndromes have underlying poor placental trophoblast cell invasion into uterine tissues. Placental invasion is controlled by many hormones and growth factors. Myostatin (MSTN) is a transforming growth factor‐β superfamily member recognized for its important role in muscle growth control. MSTN has also been shown to be secreted and functioning in the placenta, and its serum and/or placental levels were found to be upregulated in preeclampsia and intrauterine growth restriction. Considering that the mechanistic role of MSTN in placentation remains poorly understood, we hypothesized that MSTN uses ALK4/5‐SMAD2/3/4 signaling to increase human trophoblast invasion through a group of epithelial–mesenchymal transition genes including SERPINE2, PAI‐1, and SOX4. mRNA sequencing of control and MSTN‐treated primary human trophoblast cells (n = 5) yielded a total of 610 differentially expressed genes (false discovery rate <0.05) of which 380 genes were upregulated and 230 were downregulated. These differentially expressed genes were highly enriched in epithelial–mesenchymal transition genes, and a subset including SERPINE2, PAI‐1, and SOX4 was investigated for its role in MSTN‐induced trophoblast cell invasion. We found that MSTN induced upregulation of SERPINE2 via ALK4/5‐SMAD2/3/4 signaling; however, SMAD2 was not involved in MSTN‐induced PAI‐1 upregulation. SOX4 was involved in MSTN‐induced upregulation of SERPINE2, but not PAI‐1. Collectively, this study discovers novel molecular mechanisms of MSTN‐induced human trophoblast cell invasion and provides insight into the functional consequences of its dysregulation in placental insufficiency disorders. [ABSTRACT FROM AUTHOR]

Extravillous cytotrophoblasts (EVTs) invade into the uterine wall and remodel spiral arteries for proper placentation. Studies from us and others have demonstrated that the transforming growth factor‐β superfamily member bone morphogenetic protein 2 (BMP2) plays important roles in endometrial decidualization and trophoblast cell invasion. However, BMP2 has also been shown to regulate endothelial cell migration and capillary‐like tube formation, as has its downstream signaling molecule inhibitor of DNA binding 1 (ID1). Interestingly, insulin‐like growth factor binding protein 3 (IGFBP3) also promotes cell migration and angiogenesis in endothelial precursor cell. Moreover, Id1 has a regulatory effect on Igfbp3 expression in rat prostate epithelial cells. However, whether ID1 and IGFBP3 are integrated in BMP2 signaling and involved in the regulation of trophoblast invasive and endovascular differentiation remains unknown. The objective of our study was to examine the effects of BMP2 on ID1 and IGFBP3 expression and their roles in BMP2‐regulated human trophoblast invasion and endothelial‐like tube formation. Primary and immortalized (HTR8/SVneo) cultures of human trophoblast cells were employed as study models. BMP2 treatment increased ID1 and IGFBP3 mRNA and protein levels in HTR8/SVneo and primary human EVT cells. Intriguingly, ID1 was essential for BMP2‐induced IGFBP3 upregulation in both study models, and BMP2‐induced trophoblast invasion was attenuated by knockdown of either ID1 or IGFBP3. In addition, BMP2 significantly increased endothelial‐like tube formation and knockdown of ID1 and IGFBP3 reduced basal and BMP2‐induced tube formation in HTR8/SVneo cells. Similarly, BMP2 increased placenta growth factor (PlGF) production in HTR8/SVneo cells and these effects were attenuated by knockdown of ID1 or IGFBP3. Our results reveal that BMP2 promotes trophoblast cell invasion and endothelial‐like tube formation by ID1‐mediated IGFBP3 upregulation. [ABSTRACT FROM AUTHOR]

Connexin43 (Cx43) has been shown to regulate cell proliferation and its downregulation is correlated with poor prognosis and survival in several types of human cancer. Cx43 expression levels are frequently downregulated in human ovarian cancer, suggesting a potential role for Cx43 in regulating the progression of this disease. Epidermal growth factor (EGF) is a well-characterized hormone that stimulates ovarian cancer cell proliferation. Although EGF is able to regulate Cx43 expression in other cell types, it is unclear whether EGF can regulate Cx43 expression in ovarian cancer cells. Additionally, it remains unknown whether Cx43 is involved in EGF-stimulated ovarian cancer cell proliferation. In the present study, we demonstrate that treatment with EGF upregulates Cx43 expression in two ovarian cancer cell lines, SKOV3 and OVCAR4. Although treatment with EGF activates both ERK1/2 and Akt signaling pathways, pharmacological inhibition and siRNA-mediated knockdown suggest that only the activation of Akt1 is required for EGF-induced Cx43 upregulation. Functionally, Cx43 knockdown enhanced basal and EGF-induced cell proliferation, whereas the proliferative effects of EGF were reduced by Cx43 overexpression. Co-treatment with the gap junction inhibitor carbenoxolone did not alter the suppressive effects of Cx43 overexpression on EGF-induced cell proliferation, suggesting a gap junction-independent mechanism. This study reveals an important role for Cx43 as a negative regulator of EGF-induced human ovarian cancer cell proliferation. J. Cell. Physiol. 230: 111-119, 2016. © 2015 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]