Methylation status and expression of E-cadherin and cadherin-11 in gestational trophoblastic diseases

Gestational trophoblastic neoplasms (GTNs) do not display epithelial-to-mesenchymal transition (EMT) features

Although epithelial-to-mesenchymal transition (EMT) has been described in the development of complete hydatidiform moles and the invasion of the maternal decidua by trophoblasts during normal human placentation, its implication in gestational trophoblastic neoplasm (GTN) without villi is totally unknown. We studied the immunoexpression of EMT transcription factors (TWIST1, ZEB1, ZEB2), E-cadherin, and vimentin in 18 trophoblastic tumors and pseudo-tumors. Weak nuclear TWIST1 immunostaining was seen in 5% to 10% of all trophoblastic cells, without ZEB1 and ZEB2 nuclear staining. Trophoblastic cells did not express vimentin, and the expression of E-cadherin was maintained in all cases, indicating the absence of EMT features in GTN.

Methylated oligonucleotide (MON)-induced promoter hypermethylation is associated with repression of CDH1 expression and contributes to the migration and invasion of human trophoblast cell lines

DNA cytosine-5 methylation plays a vital role in regulating the expression of E-cadherin, which is encoded by the CDH1 gene. In this study, we characterised the DNA methylation and expression pattern of CDH1 in an extravillous trophoblast cell line (HTR-8/SVneo) and two trophoblast cell lines -- JEG-3 and JAR. Promoter hypermethylation with reduced E-cadherin expression in HTR-8/SVneo cells and promoter hypomethylation with increased E-cadherin expression in JEG-3 and JAR cells were observed. Demethylation treatment significantly restored E-cadherin expression, contributing to decreases in the motility and invasiveness of HTR-8/SVneo cells. Sense-methylated oligonucleotides (MONs) labelled with Cy5 and complementary to a region of the human CDH1 promoter were designed, with the cytosines in 5'-cytosine-phosphate-guanine-3' (CpG) dinucleotides being replaced by methylated cytosines. Following MON transfection into JEG-3 cells, the level of CDH1 promoter DNA methylation as well as cell motility and invasiveness were increased and gene expression was significantly repressed. Our results indicate that MON-mediated DNA methylation of the CDH1 promoter and subsequent alterations in gene expression may contribute to trophoblast motility and invasion, suggesting a potential method for controlling the biological function of trophoblasts in vitro through epigenetic modification.

Diagnostic Utility of Twist1, Ki-67, and E-Cadherin in Diagnosing Molar Gestations and Hydropic Abortions

OBJECTIVES

This study aims to assess whether the expression of Twist1, Ki-67, and E-cadherin can guide the differential diagnosis of complete hydatidiform mole (CHM), partial hydatidiform mole (PHM), and hydropic abortion (HA).

METHODS

Differential expression of Twist1, Ki-67, and E-cadherin was analyzed in gestational products from 55 cases of CHM, PHM, and HA using immunohistochemistry. Prior to analysis, the studied cases were confirmed for their diagnosis by flow cytometric assessment of DNA ploidy and p57 immunostaining.

RESULTS

Twist1 expression can distinguish CHM from PHM and HA with 100% sensitivity, 100%, specificity, 100% positive predictive value (PPV), and 100% negative predictive value (NPV). Furthermore, combined Ki-67 and E-cadherin expression could differentiate PHM and HA with 100% sensitivity, 93.3% specificity, 92.3% PPV, and 100% NPV.

CONCLUSIONS

Twist1 expression is a highly reliable marker for the diagnosis of CHM, where combined Ki-67 and E-cadherin immunoreactivity can distinguish PHM from nonmolar pregnancies.

The physiologic and therapeutic role of heparin in implantation and placentation

Implantation, trophoblast development and placentation are crucial processes in the establishment and development of normal pregnancy. Abnormalities of these processes can lead to pregnancy complications known as the great obstetrical syndromes: preeclampsia, intrauterine growth restriction, fetal demise, premature prelabor rupture of membranes, preterm labor, and recurrent pregnancy loss. There is mounting evidence regarding the physiological and therapeutic role of heparins in the establishment of normal gestation and as a modality for treatment and prevention of pregnancy complications. In this review, we will summarize the properties and the physiological contributions of heparins to the success of implantation, placentation and normal pregnancy.

Differential methylation of genes associated with cell adhesion in preeclamptic placentas

Preeclampsia (PE), a hypertensive disorder of pregnancy, is hypothesized to be associated with, if not mechanistically related to abnormal placental function. However, the exact mechanisms regulating the pathogenesis of PE remain unclear. While many studies have investigated changes in gene expression in the PE placenta, the role of epigenetics in PE associated placental dysfunction remains unclear. Using the genome-wide Illumina Infinium Methylation 450 BeadChip array, we analyzed gene-specific alterations in DNA methylation in placental biopsies collected from normal pregnant women delivering at term (n = 14), with term PE (≥37 weeks; n = 19) or with preterm PE (<37 weeks, n = 12). Of the 485,582 gene loci on the array, compared to controls, 229 loci were differentially methylated in PE placentas and 3411 loci were differentially methylated in preterm PE (step up p-value <0.05 and >5% methylation difference). Functional annotation of the differentially methylated genes in preterm PE placentas revealed a 32 gene cluster in the cadherin and cell adhesion functional groups (Benjamini p<0.00001). Hypermethylation of CDH11 (p = 0.0143), COL5A1 (p = 0.0127) and TNF (p = 0.0098) and hypomethylation of NCAM1 (p = 0.0158) was associated with altered mRNA expression in preterm PE placentas. Demethylation of first trimester extravillous trophoblast cells resulted in altered CDH11 (p = 0.0087), COL5A1 (p = 0.0043), NCAM1 (p = 0.0260) and TNF (p = 0.0022) mRNA expression. These studies demonstrate aberrant methylation, correlating with disease severity, in PE placentas. Furthermore, we provide evidence that disruption of gene-specific methylation in preterm PE placentas and first trimester trophoblasts is significantly associated with altered gene expression demonstrating that epigenetic modifications early in pregnancy can have effects on trophoblast function contributing to PE.

Immunolocalization of cell cycle proteins (p57, p27, cyclin D3, PCNA and Ki67) in intrauterine growth retardation (IUGR) and normal human term placentas

Placental development involves a series of events that depend on the coordinated action of proliferation, differentiation and invasion of trophoblasts. Studies on cell cycle related proteins controlling these events are fairly limited. It is still not fully determined how placental tissue proliferation is affected by intrauterine growth retardation (IUGR). Information on cell cycle related proteins that control these events is limited and how they are affected in IUGR is not fully understood. The aim of this study was to understand the role of cell cycle regulators in IUGR placentas and to determine the spatio-temporal immunolocalization of these cell cycle regulators in human IUGR and normal term placentas. Placental samples were stained immunohistochemically with PCNA, Ki67, cyclin D3, p27 and p57 antibodies and were examined by light microscopy. In all regions of IUGR placentas, PCNA, Ki67 and cyclin D3 staining intensities were statistically significantly decreased compared to normal controls. p27 staining intensity of the IUGR group was statistically significantly increased in villous parts and chorionic plates in comparison with the normal term placentas. Moreover, p57 staining intensity was statistically significantly increased in all parts of the IUGR group compared to controls. The observed placental abnormalities in IUGR placentas may be associated with arrest mechanisms affecting cell proliferation and cell cycle alterations in IUGR.

Downregulation of ASPP2 in choriocarcinoma contributes to increased migratory potential through Src signaling pathway activation

Gestational choriocarcinoma is a malignant tumor derived from placental trophoblast and the most aggressive member of gestational trophoblastic disease (GTD). Apoptosis-stimulating protein of p53-2 (ASPP2) is a member of ASPP family that transactivates p53 and thereby functions as a tumor suppressor. In this study, the expression profile of ASPP2 in choriocarcinoma was examined in comparison with normal placentas and hydatidiform moles, the latter being a type of GTD that carries malignant potential. Downregulation of ASPP2 messenger RNA and protein was demonstrated in choriocarcinoma by quantitative PCR and immunohistochemistry. ASPP2-transfected choriocarcinoma cells (JEG-3 and JAR) showed an increase in apoptosis and a decrease in cell migration as detected by TdT-mediated dUTP nick end labeling and wound healing assays, respectively, illustrating the complex action of ASPP2 on cell functions other than programmed cell death. Activated Src is known to be important in tumor progression. Transfection of ASPP2 but not ASPP1, another tumor-suppressive ASPP, was found to be related to subsequent decreased Src-pY416 phosphorylation, suggesting an inactivating effect of ASPP2 on Src. Moreover, this ASPP2-mediated inactivation of Src could be abolished by RNA interference with C-terminal Src kinase (Csk), a kinase that can inhibit Src activation. Our findings suggested that the ability of ASPP2 to attenuate Src activation was specific to ASPP2 in a Csk-dependent manner. Taken together, we demonstrated a loss of tumor-suppressive ASPP2 in choriocarcinoma with effects on cell migration and apoptosis. We also unveiled a possible mechanistic link between ASPP2 and Csk/Src signaling pathway, implicating the multiple cellular functions of ASPP2.

Aberrant expression of E-cadherin and β-catenin proteins in placenta of bovine embryos derived from somatic cell nuclear transfer

Abnormal placental development is common in the bovine somatic cell nuclear transfer (SCNT)-derived fetus. In the present study, we characterised the expression of E-cadherin and β-catenin, structural proteins of adherens junctions, in SCNT gestations as a model for impaired placentation. Cotyledonary tissues were separated from pregnant uteri of SCNT (n = 6) and control pregnancies (n = 8) obtained by artificial insemination. Samples were analysed by western blot, quantitative RT-PCR (qRT-PCR) and immunohistochemistry. Bovine trophectoderm cell lines derived from SCNT and control embryos were analysed to compare with the in utero condition. Although no differences in E-cadherin or β-catenin mRNA abundance were observed in fetal tissues between the two groups, proteins encoded by these genes were markedly under-expressed in SCNT trophoblast cells. Immunohistochemistry revealed a different pattern of E-cadherin and total β-catenin localisation in SCNT placentas compared with controls. No difference was observed in subcellular localisation of dephosphorylated active-β-catenin protein in SCNT tissues compared with controls. However, qRT-PCR confirmed that the wingless (WNT)/β-catenin signalling pathway target genes CCND1, CLDN1 and MSX1 were downregulated in SCNT placentas. No differences were detected between two groups of bovine trophectoderm cell lines. Our results suggest that impaired expression of E-cadherin and β-catenin proteins, along with defective β-catenin signalling during embryo attachment, specifically during placentation, is a molecular mechanism explaining insufficient placentation in the bovine SCNT-derived fetus.

Embryo-maternal communication: signalling before and during placentation in cattle and pig

Communication during early pregnancy is essential for successful reproduction. In this review we address the beginning of the communication between mother and developing embryo; including morphological and transcriptional changes in the endometrium as well as epigenetic regulation mechanisms directing the placentation. An increasing knowledge of the embryo-maternal communication might not only help to improve the fertility of our farm animals but also our understanding of human health and reproduction.

Establishment of a choriocarcinoma model from immortalized normal extravillous trophoblast cells transduced with HRASV12

Gestational choriocarcinoma is a malignant trophoblastic tumor. The development of novel molecular-targeted therapies is needed to reduce the toxicity of current multiagent chemotherapy and to treat successfully the chemoresistant cases. The molecular mechanisms underlying choriocarcinoma tumorigenesis remain uncharacterized, however, and appropriate choriocarcinoma animal models have not yet been developed. In this study, we established a choriocarcinoma model by inoculating mice with induced-choriocarcinoma cell-1 (iC³-1) cells, generated from HTR8/SVneo human trophoblastic cells retrovirally transduced with activated H-RAS (HRASV12). The iC³-1 cells exhibited constitutive activation of the mitogen-activated protein kinase (MAPK) and phosphatidylinositol 3-kinase (PI3K) pathways and developed into lethal tumors in all inoculated mice. Histopathological analysis revealed that the tumors consisted of two distinct types of cells, reminiscent of syncytiotrophoblasts and cytotrophoblasts, as seen in the human choriocarcinoma. The tumors expressed HLA-G and cytokeratin (trophoblast markers) and hCG (a choriocarcinoma marker). Comparative analysis of gene expression profiles between iC³-1 cells and parental HTR8/SVneo cells revealed that iC³-1 cells expressed matrix metalloproteinases, epithelial-mesenchymal transition-related genes, and SOX3 at higher levels than parental trophoblastic cells. Administration of SOX3-specific short-hairpin RNA decreased SOX3 expression and attenuated the tumorigenic activity of iC³-1 cells, suggesting that SOX3 overexpression might be critically involved in the pathogenesis of choriocarcinoma. Our murine model represents a potent new tool for studying the pathogenesis and treatment of choriocarcinoma.

Evaluating DNA methylation and gene expression variability in the human term placenta

Obtaining representative samples from a term placenta for gene-expression studies is confounded by both within placental heterogeneity and sampling effects such as sample location and processing time. Epigenetic processes involved in the regulation of gene expression, such as DNA methylation, may show similar variability, but are less well studied. Therefore, we investigated the nature of within and between- placenta variation in gene expression and DNA methylation of genes that were chosen for being differentially expressed or methylated by cell type within the placenta.

METHODS

In total, two or more samples from each of 38 normal term placentae were utilized. The expression levels of CDH1, CDH11, ID2, PLAC1 and KISS1 were evaluated by real-time PCR. DNA methylation levels of LINE1 elements and CpGs within the promoter regions of KISS1, PTPN6, CASP8, and APC were similarly quantified by pyrosequencing.

RESULTS

Despite considerable sample-to-sample variability within each placenta, the within-placenta correlation for both gene expression and methylation was significant for each studied gene. Most of this variability was not due to sample location. However, between placental differences in gene expression were inflated by the dramatic effect of processing time (0-24 h) on mRNA levels, particularly for PLAC1 and KISS1 (both expressed in the apical syncytiotrophoblast). In contrast, DNA methylation levels remained relatively constant over this same time period.

CONCLUSION

Due to extensive site-to-site variability, multiple sampled sites are needed to accurately represent a placenta for molecular studies. Furthermore, mRNA quantitation of some genes may be hampered by its rapid degradation post-delivery (and possibly perinatally) and thus processing time should be considered in such analyses. Within-placenta correlations in expression and methylation from unrelated genes raise the possibility that methylation and expression variation may potentially reflect cell composition differences between samples rather than true differences occurring at the cellular level.

Luteal phase empirical low molecular weight heparin administration in patients with failed ICSI embryo transfer cycles: a randomized open-labeled pilot trial

BACKGROUND

The pathology underlying recurrent implantation failures (RIF) is not clear and treatment options proposed are generally not evidence based. Although the effect of heparin on trophoblast biology has not been studied extensively, given the available data suggesting a possible beneficial effect of heparin on embryo implantation, we decided to undertake this pilot study.

METHODS

One hundred and fifty women with > or =2 failed assisted reproduction treatment cycles were included in this randomized open-label pilot trial. Participants underwent controlled ovarian stimulation with the long protocol and were randomly allocated to receive 1 mg/kg/day low molecular weight heparin (LMWH) or no treatment in addition to routine luteal phase support (LPS) on the day after oocyte retrieval. LPS and LMWH was continued up to the 12th gestational week in pregnant participants.

RESULTS

There were 26 (34.7%) live births in the LMWH group, and 20 (26.7%) in the control group (absolute difference 8.0%, 95% CI -4.2 to 24.9%, P = 0.29). There were 34 (45.3%) and 29 (38.7%) clinical pregnancies in the LMWH and control groups, respectively (absolute difference 6.6%, 95% CI -9.0 to 21.8%, P = 0.41). Implantation rates were 24.5 and 19.8% in the LMWH and control groups, respectively (absolute difference 4.7%, 95% CI -4.7 to 14.1%, P = 0.33).

CONCLUSION

Despite lack of statistical significance, observed relative increase by 30% in live birth rates with LMWH may be regarded as a clinically significant trend necessitating further research on the use of empirical LMWH in women with RIF and possibly in all women undergoing assisted reproduction treatment. Failure to demonstrate statistical significance of the observed treatment difference may be due to limited sample size of this pilot study.

Activated Stat3 expression in gestational trophoblastic disease: correlation with clinicopathological parameters and apoptotic indices

AIMS

To assess the expression profile of the activated form of signal transducer and activator of transcription (Stat)3 in gestational trophoblastic disease (GTD) and correlate the findings with clinicopathological parameters.

METHODS AND RESULTS

By immunohistochemistry, both cytoplasmic and nuclear expression of p-Stat3-Ser(727) was demonstrated in 88 trophoblastic tissues, including placentas and GTD. Nuclear immunoreactivity of p-Stat3-Ser(727) was significantly higher in hydatidiform mole (HM) (P < 0.001) and choriocarcinoma (P = 0.009) when compared with normal placentas. Placental site trophoblastic tumours (PSTT) and epithelioid trophoblastic tumours (ETT) also demonstrated higher nuclear p-Stat3-Ser(727) expression than their normal trophoblast counterparts. Higher p-Stat3-Ser(727) expression was confirmed in choriocarcinoma cell lines, JEG-3 and JAR, than in a normal trophoblast cell line, with both nuclear and cytoplasmic fractions demonstrated by immunoblotting. Spontaneously regressed HM showed significantly increased nuclear and cytoplasmic p-Stat3-Ser(727) immunoreactivity over those that developed gestational trophoblastic neoplasia (GTN) (P = 0.013, P = 0.039). There was a significant positive and inverse correlation between nuclear p-Stat3-Ser(727) immunoreactivity and apoptotic indices [terminal deoxynucleotidyl transferase (TdT)-mediated deoxyuridine triphosphate (dUTP) nick end labelling and M30 CytoDeath antibody] (P = 0.001, P < 0.001, Spearman's rho test) and Bcl-2 expression (P = 0.034), respectively.

CONCLUSIONS

p-Stat3-Ser(727) plays a role in the pathogenesis of GTD, probably through the regulation of apoptosis. p-Stat3-Ser(727) immunoreactivity is a potential marker in predicting GTN in HM.

Molecular targets in gynaecological cancers

The application of high throughput expression profiling and other advanced molecular biology laboratory techniques has revolutionised the management of cancers and is gaining attention in the field of gynaecological cancers. Such new approaches may help to improve our understanding of carcinogenesis and facilitate screening and early detection of gynaecological cancers and their precursors. Individualised prediction of patients' responses to therapy and design of personalised molecular targeted therapy is also possible. The studies of various molecular targets involved in the various signal pathways related to carcinogenesis are particularly relevant to such applications. At the moment, the application of detection and genotyping of human papillomavirus in management of cervical cancer is one of the most well established appliances of molecular targets in gynaecological cancers. Methylation, telomerase and clonality studies are also potentially useful, especially in assisting diagnosis of difficult clinical scenarios. This post-genomic era of clinical medicine will continue to make a significant impact in routine pathology practice. The contribution of pathologists is indispensable in analysis involving tissue microarray. On the other hand, both pathologists and bedside clinicians should be aware of the limitation of these molecular targets. Interpretation must be integrated with clinical and histopathological context to avoid misleading judgement. The importance of quality assurance of all such molecular techniques and their ethical implications cannot be over-emphasised.

Investigation of the effects of heparin and low molecular weight heparin on E-cadherin and laminin expression in rat pregnancy by immunohistochemistry

BACKGROUND

Heparin and low molecular weight heparin (LMWH) are used widely to improve the pregnancy outcome in women with thrombophilia, miscarriage, recurrent miscarriage and fetal death. This study was designed to investigate the effects of heparin and LMWHs, enoxaparin and tinzaparin, on E-cadherin and laminin expression in placental and decidual tissues in rat pregnancy.

METHODS

Wistar albino female rats (n = 48) were randomly assigned to four study groups (normal saline, heparin, enoxaparin and tinzaparin) in the preconceptional period. Tissue sections of placenta and decidua were immunohistochemically examined for the expression of E-cadherin and laminin.

RESULTS

E-cadherin placental staining score of heparin group was significantly lower and E-cadherin decidual staining score of heparin and enoxaparin groups were significantly lower than control group. There were no significant differences in placental and decidual laminin staining scores among the study groups.

CONCLUSIONS

Heparin and enoxaparin can reduce E-cadherin expression but not laminin expression in rat pregnancy. They might modulate trophoblast invasion. We suggest that this is the possible underlying mechanism involving in improvement of trophoblast invasion by the use of heparin and LMWH in patients with the history of miscarriage.

Promoter methylation and differential expression of pi-class glutathione S-transferase in endometrial carcinoma

Pi-class glutathione S-transferase (GSTP1), located on chromosome 11q13, codes for a phase II metabolic enzyme that detoxifies reactive electrophilic intermediates. The protein also interacts with steroid hormones in the human body. The role of GSTP1 in endometrial carcinoma has not been reported. In this study, we aimed at determining the expression of GSTP1 in relation to the epigenetic and genetic changes of the gene in endometrial carcinoma. The GSTP1 protein and mRNA expression was assessed by immunohistochemistry on tissue microarray and quantitative real-time reverse transcriptase-polymerase chain reaction, respectively. Its methylation status was studied by methylation-specific polymerase chain reaction and bisulfite sequencing. Possible mutations in coding region of GSTP1 were assessed by cDNA sequencing. Ninety-seven cases of endometrial carcinoma with available tissue blocks and clinical data were studied. Our results showed that 68.0% (66 of 97) of the cases showed reduced protein expression while 64% (16 of 25) showed reduced mRNA expression; 30.9% (30 of 97) of the cases demonstrated methylated alleles in at least one of the six methylation-specific polymerase chain reaction reactions. The methylation status significantly correlated with reduced protein expression (P = 0.008) and reduced mRNA expression (P = 0.003). Methylation at non-CpG sites including CpCpG trinucleotides and CpT dinucleotides were also observed. cDNA sequencing did not reveal genetic alterations in coding region of the gene. The extent of myometrial invasion was found to be significantly correlated with both the methylation status (P = 0.009) and the protein expression (P = 0.036) of the GSTP1 gene. We postulated that hypermethylation of the GSTP1 gene promoter region may act as a dynamic regulation mechanism contributing to reduced GSTP1 expression, which is associated with myometrial invasion potential of the endometrial carcinoma.

Inhibition of DLX4 promotes apoptosis in choriocarcinoma cell lines

Homeodomain (HDM) proteins encoded by homeobox (HBX) genes represent a large family of transcriptional factors that control differentiation and development in certain cell types. DLX4 is a member of Distal-less (DLX) family of HBX genes. Recent studies have demonstrated that abnormal expression of DLX4 is present in several types of human tumors, such as breast cancer, leukemia and colon cancer. In the present study, we investigated DLX4 mRNA and protein expression in both normal placental tissues and human choriocarcinoma cell lines. Also, using RNA interference (RNAi) technique, we knocked down the expression of DLX4 and examined apoptosis in JEG-3 cells. Our studies demonstrated that DLX4 RNAi inhibited DLX4 mRNA expression and decreased DLX4 protein mass specifically and effectively, potentially enhancing apoptosis. Moreover, we examined expression of caspase-3 and caspase-8, and found that both caspases were increased after DLX4 knockdown. However, DLX4 RNAi did not influence Bax expression in JEG-3 cells. In conclusion, this study suggests that DLX4 may be involved in the survival of human choriocarcinoma cells, which may be mediated by the inhibition of apoptosis. The detailed mechanism needs further investigation.

Promoter hypermethylation of multiple genes in hydatidiform mole and choriocarcinoma

The methylation status of genes in hydatidiform mole and choriocarcinoma and its significance is relatively unexplored. We investigated the methylation status of the promoter regions of six genes, p16, HIC-1, TIMP3, GSTP1, death-associated protein kinase (DAPK), and E-cadherin in 54 hydatidiform moles, five choriocarcinomas, and 10 first trimester placenta by methylation-specific polymerase chain reaction (PCR). Immunohistochemical expression of p16, TIMP3, and E-cadherin, and quantitative real-time RT-PCR of p16 was also performed. Among the six genes examined, the promoter region of four genes (E-cadherin, HIC-1, p16, TIMP3) in choriocarcinoma and three genes (E-cadherin, HIC-1, p16) in hydatidiform mole exhibited aberrant methylation whereas none was hypermethylated in normal placenta. There was a significant correlation between methylation and reduced expression of p16, E-cadherin, and TIMP3 (P < 0.001). Fifteen of the 54 patients with hydatidiform mole developed gestational trophoblastic neoplasia requiring chemotherapy. Promoter hypermethylation of p16 alone, or combined with E-cadherin, was significantly correlated to such development (P = 0.001, 0.0005, respectively). Hypermethylation of multiple genes, especially p16, might be related to the subsequent development of gestational trophoblastic neoplasia.

Mcl-1 expression in gestational trophoblastic disease correlates with clinical outcome

BACKGROUND

Hydatidiform moles (HMs) are abnormal pregnancies with a propensity for developing persistent disease in the form of gestational trophoblastic neoplasia (GTN), which requires chemotherapy. In previous studies, the authors demonstrated that low apoptotic activity was correlated with the progression of HM to GTN, and they hypothesized that some apoptosis-related genes may determine this progression.

METHODS

The differential expression of apoptotic genes in HMs that subsequently developed into GTN was compared with the same expression in HMs that spontaneously regressed using a human apoptosis array; then, the expression was evaluated with real-time quantitative polymerase chain reaction analysis and immunohistochemistry using 54 clinical samples from patients with HMs who had follow-up data available.

RESULTS

Using an apoptosis array, greater expression of Mcl-1, which is an antiapoptotic gene, was detected in HMs that subsequently developed into GTN. It was confirmed that the levels of Mcl-1 RNA expression (P = 0.017) and Mcl-1 protein expression (P < 0.001) in HMs that developed into persistent disease and required chemotherapy were significantly greater compared with the levels in HMs that regressed. Moreover, Mcl-1 immunoreactivity, which was detected predominantly in cytotrophoblasts, was correlated with the apoptotic index, as assessed with M30 cytoDeath immunohistochemistry, which is a good indicator of apoptotic events in the early-stage disease.

CONCLUSIONS

The current results demonstrated that Mcl-1, as identified by a cyclic DNA array, may play a role in the pathogenesis of HMs and may have potential as a useful marker for predicting the clinical behavior of HMs.

Down-regulation and promoter methylation of tissue inhibitor of metalloproteinase 3 in choriocarcinoma

OBJECTIVE

To assess the differential gene expression in neoplastic and normal trophoblastic cells and evaluate the effect of methylation on tissue inhibitor of metalloproteinase 3 (TIMP3) expression in choriocarcinoma (CCA) cells.

METHODS

The Atlas Human Cancer 1.2 Array (Clontech) was used to compare differential gene expression in a trophoblastic cell line (B6) established from first term placenta with two choriocarcinoma cell lines (JAR and JEG-3). The differentially expressed candidate genes in the placental and malignant trophoblastic cells in these cell lines were confirmed by real-time polymerase chain reaction (PCR), Western blotting and immunohistochemistry. Differential expression of a specific gene, TIMP3, was confirmed by immunohistochemistry using clinical specimens of choriocarcinoma and placenta. The involvement of promoter methylation in suppression of TIMP3 expression in choriocarcinoma was examined using methylation-specific PCR (MSP) and demethylation treatment.

RESULTS

Differential expression of 23 genes was observed in choriocarcinoma cell lines compared to the placental trophoblastic cells using the cDNA array analysis (Atlas Human Cancer Array, Clontech). Among these differentially expressed genes, down-regulation of TIMP3, PLAB, IGFBP3 and up-regulation of CCNB1 were confirmed by real-time PCR determination. Reduced expression of TIMP3 was further confirmed in clinical samples of choriocarcinoma by immunohistochemical staining. Methylation of TIMP3 promoter was detected in choriocarcinoma cell lines and clinical samples of choriocarcinoma. Treatment with a demethylation drug, 5-aza-2'-deoxycytidine, in choriocarcinoma cell lines restored TIMP3 expression.

CONCLUSION

Down-regulation of TIMP3, PLAB, IGFBP3 and up-regulation of CCNB1 were observed in choriocarcinoma cells compared to placental trophoblasts. Down-regulation of TIMP3 expression was confirmed in clinical specimens of choriocarcinoma and may play a role in its pathogenesis. Promoter methylation of the TIMP3 is involved in suppression of TIMP3 expression. Differentiation expression of TIMP3 in choriocarcinoma may have potential application in clinical diagnosis and patient treatment.