Dysregulated activation of c-Src in gestational trophoblastic disease contributes to its aggressive progression

N-linked α2,6-sialylation of integrin β1 by the sialyltransferase ST6Gal1 promotes cell proliferation and stemness in gestational trophoblastic disease

INTRODUCTION

Gestational trophoblastic disease (GTD) encompasses a spectrum of rare pre-malignant and malignant entities originating from trophoblastic tissue, including partial hydatidiform mole, complete hydatidiform mole and choriocarcinoma. β-galactoside α2,6 sialyltransferase 1 (ST6Gal1), the primary sialyltransferase responsible for the addition of α2,6 sialic acids, is strongly associated with the occurrence and development of several tumor types. However, the role of ST6Gal1/α2,6 -sialylation of trophoblast cells in GTD is still not well understood.

METHODS

The expression of ST6Gal1 was investigated in GTD and human immortalized trophoblastic HTR-8/SVneo cells and human gestational choriocarcinoma JAR cells. We evaluated the effect of ST6Gal1 on proliferation and stemness of trophoblastic cells. We also examined the effect of internal miR-199a-5p on ST6Gal1 expression. The role of ST6Gal1 in regulating α2,6-sialylated integrin β1 and its significance in the activation of integrin β1/focal adhesion kinase (FAK) signaling pathway were also explored.

RESULTS

ST6Gal1 was observed to be highly expressed in GTD. Overexpression of ST6Gal1 promoted the proliferation and stemness of HTR-8/SVneo cells, whereas knockdown of ST6Gal1 suppressed the viability and stemness of JAR cells. MiR-199a-5p targeted and inhibited the expression of ST6Gal1 in trophoblastic cells. In addition, we revealed integrin β1 was highly α2,6-sialylated in JAR cells. Inhibition of ST6Gal1 reduced α2,6-sialylation on integrin β1 and suppressed the integrin β1/FAK pathway in JAR cells, thereby affecting its biological functions.

DISCUSSION

This study demonstrated that ST6Gal1 plays important roles in promoting proliferation and stemness through the integrin β1 signaling pathway in GTD. Therefore, ST6Gal1 may have a potential role in the occurrence and development of GTD.

Downregulation of PDCD4 by deSUMOylation associates with the progression of gestational trophoblastic disease

INTRODUCTION

Gestational trophoblastic disease (GTD) encompasses a range of trophoblastic disorders from hydatidiform mole (HM), to malignant gestational trophoblastic neoplasia (GTN). The exact molecular mechanisms of GTN remain unknown. Dysregulation and dysfunction of programmed cell death 4 (PDCD4)have been observed in many cancers. The roles of PDCD4 in GTD have not been previously reported.

METHODS

A total of 161 cases of formalin-fixed, paraffin-embedded trophoblast blocks, and 36 cases of fresh trophoblast tissues were collected, including normal first trimester placentas, HM, and invasive HM. Choriocarcinoma cells JAR and JEG-3 were employed. The expressions of PDCD4 and small ubiquitin-like modifier 2/3 (SUMO2/3) were examined by immunohistochemistry, quantitative reverse transcription PCR and Western blotting in trophoblastic tissues and cells. The relationship between SUMOylation and PDCD4 was investigated. The effects of PDCD4 on proliferation, invasion, and migration of choriocarcinoma cells were evaluated by Cell Counting Kit-8 and transwell assays post siRNA transfection. Extracellular Matrix & Adhesion Profiler PCR Array was used to screen the downstream molecules of PDCD4.

RESULTS

PDCD4 was significantly repressed in HM tissues. Loss of PDCD4 expression was demonstrated in 90% invasive HMs. Choriocarcinoma cells also displayed with suppressed PDCD4 expression. The varied expression of PDCD4 was paralleled by SUMO2/3. Inhibition of SUMOylation reduced the expression of PDCD4. Silencing of PDCD4promoted proliferation/migration/invasion, upregulatedMMP3/MMP8/ITGB2, and downregulated TIMP1/TIMP2 in choriocarcinoma cells.

DISCUSSION

Our results suggest that reduced SUMOylation is one reason for suppressed PDCD4 in GTD. Loss of PDCD4 likely determines the malignant phenotype of GTN by dysregulating some members of the MMPs/TIMPs/integrins complex.

Chronic activation of FXR-induced liver growth with tissue-specific targeting Cyclin D1

The nuclear receptor (FXR) plays essential roles in maintaining bile acid and lipid homeostasis by regulating diverse target genes. And its agonists were promising agents for treating various liver diseases. Nevertheless, the potential side effect of chronic FXR activation by specific agonists is not fully understood. In this study, we investigated the mechanism of FXR agonist WAY-362450 induced liver enlargement during treating liver diseases. We demonstrated that chronic ingestion of WAY-362450 induced liver hypertrophy instead of hyperplasia in mouse. Global transcriptional pattern was also examined in mouse livers after treatment with WAY-362450 by RNA-seq assay. Through GO and KEGG enrichment analyses, we demonstrated that the expression of Cyclin D1 (Ccnd1) among the cell cycle-regulating genes was notably increased in WAY-362450-treated mouse liver. Activation of FXR-induced Ccnd1 expression in hepatocyte in a time-dependent manner in vivo and in vitro. Through bioinformatics analysis and ChIP assay, we identified FXR as a direct transcriptional activator of Ccnd1 through binding to a potential enhancer, which was specifically active in livers. We also found active histone acetylation was essential for Ccnd1 induction by FXR. Thus, our study indicated that activation of FXR-induced harmless liver hypertrophy with spatiotemporal modulation of Ccnd1. With a better understanding of the mechanism of tissue-specific gene regulation by FXR, it is beneficial for development and appropriate application of its specific agonist in preventing hepatic diseases.

Combined inhibition of PI3K and Src kinases demonstrates synergistic therapeutic efficacy in clear-cell renal carcinoma

Potent inhibitors of PI3K (GDC-0941) and Src (Saracatinib) exhibit as individual agents, excellent oral anticancer activity in preclinical models and have entered phase II clinical trials in various cancers. We found that PI3K and Src kinases are dysregulated in clear cell renal carcinomas (ccRCCs), an aggressive disease without effective targeted therapies. In this study we addressed this challenge by testing GDC-0941 and Saracatinib as either single agents or in combination in ccRCC cell lines, as well as in mouse and PDX models. Our findings demonstrate that combined inhibition of PI3K and Src impedes cell growth and invasion and induces cell death of renal carcinoma cells providing preclinical evidence for a pairwise combination of these anticancer drugs as a rational strategy to improve renal cancer treatment.

Identification of microRNA signature in the progression of gestational trophoblastic disease

Gestational trophoblastic disease (GTD) encompasses a range of trophoblast-derived disorders. The most common type of GTD is hydatidiform mole (HM). Some of HMs can further develop into malignant gestational trophoblastic neoplasia (GTN). Aberrant expression of microRNA (miRNA) is widely reported to be involved in the initiation and progression of cancers. MiRNA expression profile also has been proved to be the useful signature for diagnosis, staging, prognosis, and response to chemotherapy. Till now, the profile of miRNA in the progression of GTD has not been determined. In this study, a total of 34 GTN and 60 complete HMs (CHM) trophoblastic tissues were collected. By miRNA array screening and qRT-PCR validating, six miRNAs, including miR-370-3p, -371a-5p, -518a-3p, -519d-3p, -520a-3p, and -934, were identified to be differentially expressed in GTN vs. CHM. Functional analyses further proved that miR-371a-5p and miR-518a-3p promoted proliferation, migration, and invasion of choriocarcinoma cells. Moreover, we demonstrated that miR-371a-5p was negatively related to protein levels of its predictive target genes BCCIP, SOX2, and BNIP3L, while miR-518a-3p was negatively related to MST1 and EFNA4. For the first time, we proved that miR-371a-5p and miR-518a-3p directly targeted to 3′-UTR regions of BCCIP and MST1, respectively. Additionally, we found that miR-371a-5p and miR-518a-3p regulated diverse pathways related to tumorigenesis and metastasis in choriocarcinoma cells. The results presented here may offer new clues to the progression of GTD and may provide diagnostic biomarkers for GTN.

miR-21 Is Overexpressed in Hydatidiform Mole Tissues and Promotes Proliferation, Migration, and Invasion in Choriocarcinoma Cells

OBJECTIVE

The aims of this study were to make clear whether miR-21 was dysregulated in hydatidiform mole (HM) tissues and choriocarcinoma (CCA) cells, to elucidate whether aberrant miR-21 expression would affect the function of CCA cells, and to find out whether there was a relationship between miR-21 and AKT, PDCD4, and PTEN in CCA cells.

METHODS

Fresh and formalin-fixed, paraffin-embedded trophoblastic tissues (normal first trimester placentas and HMs) were retrieved from the biobank in the International Peace Maternity and Child Health Hospital, Shanghai Jiao Tong University. Choriocarcinoma JAR and JEG-3 cells were cultured. Expression of miR-21 in trophoblast cells and tissues was examined by quantitative real-time polymerase chain reaction. Location and distribution of miR-21 in trophoblast tissues were determinated by in situ hybridization and fluorescent in situ hybridization. The effect of miR-21 on JAR and JEG-3 cells was tested by miR-21 mimics and inhibitor transfection, followed by cell viability assay, flow cytometric analysis, and Transwell analysis. Interaction between miR-21 and its target genes in CCA cells was verified by quantitative real-time polymerase chain reaction, Western blot, and luciferase report system.

RESULTS

We originally found miR-21 was markedly upregulated in HM tissues compared with normal first trimester placentas. The expression of miR-21 was exclusively confined in trophoblastic layers. Furthermore, we discovered miR-21 was significantly increased in JAR and JEG-3 cells compared with normal primary human trophoblastic cells. Moreover, we demonstrated miR-21 could promote proliferation, migration, and invasion of CCA cells. We furthermore proved miR-21 negatively regulated PDCD4 and PTEN in CCA cells and targeted to PDCD4 3'UTR directly. In addition, we confirmed that miR-21 could activate Akt pathway by phosphorylating Akt at Ser 473.

CONCLUSIONS

Our results suggested miR-21 was responsible for aggressive phenotype of gestational trophoblastic disease and had the potential diagnostic and therapeutic values for gestational trophoblastic neoplasm.

Decreased PGF may contribute to trophoblast dysfunction in fetal growth restriction

Fetal growth restriction (FGR) threatens perinatal health and is correlated with increased incidence of fetal original adult diseases. Most cases of FGR were idiopathic, which were supposed to be associated with placental abnormality. Decreased circulating placental growth factor (PGF) was recognized as an indication of placental deficiency in FGR. In this study, the epigenetic regulation of PGF in FGR placentas and the involvement of PGF in modulation of trophoblast activity were investigated. The expression level of PGF in placental tissues was determined by RT-qPCR, immunohistochemistry and ELISA. DNA methylation profile of PGF gene was analyzed by bisulfite sequencing. Trophoblastic cell lines were treated with ZM-306416, an inhibitor of PGF receptor FLT1, to observe the effect of PGF/FLT1 signaling on cell proliferation and migration. We demonstrated that PGF was downregulated in placentas from FGR pregnancies compared with normal controls. The villous expression of PGF was positively correlated with placental and fetal weight. The CpG island inside PGF promoter was hypomethylated without obvious difference in both normal and FGR placentas. However, the higher DNA methylation at another CpG island downstream exon 7 of PGF was demonstrated in FGR placentas. Additionally, we found FLT1 was expressed in trophoblast cells. Inhibition of PGF/FLT1 signaling by a selective inhibitor impaired trophoblast proliferation and migration. In conclusion, our data suggested that the PGF expression was dysregulated, and disrupted PGF/FLT1 signaling in trophoblast might contribute to placenta dysfunction in FGR. Thus, our results support the significant role of PGF in the pathogenesis of FGR.

Downregulation of peroxiredoxin-3 by hydrophobic bile acid induces mitochondrial dysfunction and cellular senescence in human trophoblasts

Intrahepatic cholestasis of pregnancy (ICP) is a pregnancy-specific disorder characterised by raised bile acids in foetal-maternal circulation, which threatens perinatal health. During the progression of ICP, the effect of oxidative stress is underscored. Peroxiredoxin-3 (PRDX3) is a mitochondrial antioxidant enzyme that is crucial to balance intracellular oxidative stress. However, the role of PRDX3 in placental trophoblast cells under ICP is not fully understood. We demonstrated that the level of PRDX3 was downregulated in ICP placentas as well as bile acids–treated trophoblast cells and villous explant in vitro. Toxic levels of bile acids and PRDX3 knockdown induced oxidative stress and mitochondrial dysfunction in trophoblast cells. Moreover, silencing of PRDX3 in trophoblast cell line HTR8/SVneo induced growth arrest and cellular senescence via activation of p38-mitogen-activated protein kinase (MAPK) and induction of p21^WAF1/CIP and p16^INK4A. Additionally, enhanced cellular senescence, determined by senescence-associated beta-galactosidase staining, was obviously attenuated by p38-MAPK inhibitor SB203580. Our data determined that exposure to bile acid decreased PRDX3 level in human trophoblasts. PRDX3 protected trophoblast cells against mitochondrial dysfunction and cellular senescence induced by oxidative stress. Our results suggest that decreased PRDX3 by excessive bile acids in trophoblasts plays a critical role in the pathogenesis and progression of ICP.