Jinping Li

Correlation of Serum HE4 with Tumor Size and Myometrial Invasion in Endometrial Cancer

OBJECTIVEnTo evaluate the utility of serum (HE4) as a marker for high risk disease in patients with endometrial cancer (EC).nnnMETHODSnPreoperative serum HE4 levels were measured from a cohort of 75 patients surgically treated for EC. Cases were compared to matched controls without a history of cancer. HE4 levels were analyzed as a function of primary tumor diameter, grade, stage and histological subtype. Wilcoxon rank-sum test, ROC curve, Spearman rank correlation coefficient and contingency tables were used for statistical analyses.nnnRESULTSnStage distribution was as follows: 49 stage I, 2 stage II, 20 stage III, 4 stage IV. Type I EC was present in 54 patients, type II in 21. Median HE4 was significantly elevated in both types I and II EC compared to controls (P<0.001 and P=0.019, respectively). There was significant correlation between type I EC, median HE4, deep myometrial invasion (MI) (>50%, P<0.001) and primary tumor diameter (PTD) (>2 cm, P=0.002). Low risk patients (type I, MI ≤ 50% and PTD ≤ 2 cm) had significantly lower median HE4 compared to all other type I EC patients (P<0.01). In comparison to prior investigations, HE4 (cutoff of 8 mfi) was more sensitive than CA125 in detecting advanced stage disease.nnnCONCLUSIONnOur data suggest that HE4 is elevated in a high proportion of EC patients, is correlated with PTD and MI, and is more sensitive than CA125 in EC. These observations suggest potential utility of HE4 in the preoperative prediction of high risk disease and the necessity for definitive surgical staging.

Decreased expression and altered methylation of syncytin-1 gene in human placentas associated with preeclampsia.

Syncytin-1 is a protein coded by a human endogenous retrovirus (HERV) gene of the HERV-W family (HERVWE1). Syncytin- 1 mediates formation of syncytiotrophoblasts through fusion of cytotrophoblasts, a hallmark of terminal differentiation of placental trophoblast linage. Syncytin-1 also possesses nonfusogenic functions and regulates cell cycle progression. While decreased syncytin-1 expression and syncytium deficiency are considered important pathological changes in preeclampsia, the molecular mechanism(s) underlying syncytin-1 downregulation remains unclear. In this study, we confirmed that expression levels of syncytin-1 mRNA and protein were significantly lower in preeclamptic placentas compared to normal controls. Human chorionic somatomammotropin expression, a marker for syncytium function, was also decreased in preeclamptic placentas. The mRNA levels of ASCT2, the syncytin-1 receptor involved in cell fusion process, and GCMa, a transcriptional factor known to regulate syncytin-1 expression, were not significantly altered. Methylation in the 5LTR of syncytin-1 promoter was quantified by COBRA, methylation-specific PCR, and DNA sequencing. Results from all three assays indicated significantly hypermethylated syncytin-1 promoter in preeclamptic placentas compared to normal controls. Methylation levels were inversely correlated with syncytin-1 mRNA levels, suggesting that hypermethylation may lead to syncytin-1 downregulation. Further experiments indicated that DNMT1 and DNMT3B3 mRNA and protein levels were increased in preeclamptic placentas, suggesting that higher DNA methyltransferase activity may contribute to the hypermethylation of syncytin-1 in preeclamptic placentas. These results indicated that aberrant hypermethylation is involved in downregulation of syncytin-1, and epigenetic alterations may play a significant role in the development of preeclampsia.

Epigenetic and non-epigenetic regulation of syncytin-1 expression in human placenta and cancer tissues.

Syncytin-1 is a human endogenous retroviral envelope gene (HERVW1) product specifically expressed in placental trophoblasts. By mediating the formation of syncytiotrophoblasts through cell-cell fusion, syncytin-1 plays a critical role for the placental barrier, endocrine and exchange functions. During pregnancy, syncytin-1 expression is dynamically regulated by various pathophysiological factors and pathways. This review summarizes and examines published data on epigenetic and non-epigenetic regulation of syncytin-1 gene expression, with a focus on the changes of syncytin-1 DNA methylation and expression in placental trophoblasts under preeclamptic and hypoxic conditions. The functions of syncytiotrophoblasts, the fusogenic and non-fusogenic activities of syncytin-1, and aberrant activation of syncytin-1 expression in cancer cells are also discussed. New findings on the epigenetic regulation of syncytin-1 in placentas from monozygotic/dichorionic discordant twins are analyzed. The close correlation among changes of DNMTs expression, syncytin-1 gene methylation, and syncytin-1 mRNA levels, in placentas associated with discordant fetal growth indicated a dynamic nature of syncytin-1 regulation.

HE4 (WFDC2) Promotes Tumor Growth in Endometrial Cancer Cell Lines.

HE4, also known as WFDC2, is a useful biomarker for ovarian cancer when either used alone or in combination with CA125. HE4 is also overexpressed in endometrial cancer (EC), but its function in cancer cells is not clear. In this study, we investigate the role of HE4 in EC progression. An HE4-overexpression system was established by cloning the HE4 prototypic mRNA variant (HE4-V0) into a eukaryotic expression vector. Following transfection, stable clones in two EC cell lines were selected. The effects of HE4 overexpression on cell growth and function were measured with the use of cell proliferation assay, matrigel invasion, and soft agar gel colony formation assays. HE4-induced cancer cell proliferation in vivo was examined in a mouse xenograft model. HE4 overexpression significantly enhanced EC cell proliferation, matrigel invasion, and colony formation in soft agar. Moreover, HE4 overexpression promoted tumor growth in the mouse xenograft model. HE4 overexpression enhanced several malignant phenotypes in cell culture and in a mouse model. These results are consistent with our previous observation that high levels of serum HE4 closely correlate with the stage, myometrial invasion and tumor size in patients with EC. This study provides evidence that HE4 overexpression directly impacts tumor progression in endometrial cancer.

Reduced syncytin-1 expression in choriocarcinoma BeWo cells activates the calpain1-AIF-mediated apoptosis, implication for preeclampsia.

Placentas associated with preeclampsia are characterized by extensive apoptosis in trophoblast lineages. Syncytin-1 (HERVWE1) mediates the fusion of cytotrophoblasts to form syncytiotrophoblasts, which assume the placental barrier, fetal–maternal exchange and endocrine functions. While decreased syncytin-1 expression has been observed in preeclamptic placentas, it is not clear if this alteration is involved in trophoblast apoptosis. In the current study, we found that siRNA-mediated knockdown of syncytin-1 led to apoptosis in choriocarcinoma BeWo, a cell line of trophoblastic origin. Characterization of the apoptotic pathways indicated that this effect does not rely on the activation of caspases. Rather, decreased syncytin-1 levels activated the apoptosis inducing factor (AIF) apoptotic pathway by inducing the expression, cleavage, and nuclear translocation of AIF. Moreover, calpain1, the cysteine protease capable of cleaving AIF, was upregulated by syncytin-1 knockdown. Furthermore, treatment with calpain1 inhibitor MDL28170 effectively reversed AIF cleavage, AIF nuclear translocation, and cell apoptosis triggered by syncytin-1 downregulation, verifying the specific action of calpain1–AIF pathway in trophoblast apoptosis. We confirmed that preeclamptic placentas express lower levels of syncytin-1 than normal placentas, and observed an inverse correlation between syncytin-1 and AIF/calpain1 mRNA levels, a result consistent with the in vitro findings. Immunohistochemistry analyses indicated decreased syncytin-1 and increased AIF and calpain1 protein levels in apoptotic cells of preeclamptic placentas. These findings have for the first time revealed that decreased levels of syncytin-1 can trigger the AIF-mediated apoptosis pathway in BeWo cells. This novel mechanism may contribute to the structural and functional deficiencies of syncytium frequently observed in preeclamptic placentas.

HE4 Transcription- and Splice Variants-Specific Expression in Endometrial Cancer and Correlation with Patient Survival

We investigated the HE4 variant-specific expression patterns in various normal tissues as well as in normal and malignant endometrial tissues. The relationships between mRNA variants and age, body weight, or survival are analyzed. ICAT-labeled normal and endometrial cancer (EC) tissues were analyzed with multidimensional liquid chromatography followed by tandem mass spectrometry. Levels of HE4 mRNA variants were measured by real-time PCR. Mean mRNA levels were compared among 16 normal endometrial samples, 14 grade 1 and 14 grade 3 endometrioid EC, 15 papillary serous EC, and 14 normal human tissue samples. The relationship between levels of HE4 variants and EC patient characteristics was analyzed with the use of Pearson correlation test. We found that, although all five HE4 mRNA variants are detectable in normal tissue samples, their expression is highly tissue-specific, with epididymis, trachea, breast and endometrium containing the highest levels. HE4-V0, -V1, and -V3 are the most abundant variants in both normal and malignant tissues. All variants are significantly increased in both endometrioid and papillary serous EC, with higher levels observed in grade 3 endometrioid EC. In the EC group, HE4-V1, -V3, and -V4 levels inversely correlate with EC patient survival, whereas HE4-V0 levels positively correlate with age. HE4 variants exhibit tissue-specific expression, suggesting that each variant may exert distinct functions in normal and malignant cells. HE4 levels appear to correlate with EC patient survival in a variant-specific manner. When using HE4 as a biomarker for EC management, the effects of age should be considered.

Hypomethylation and Activation of Syncytin-1 Gene in Endometriotic Tissue

Syncytin-1 plays a critical role in the maintenance of normal pregnancy by mediating the formation of syncytiotrophoblasts through a fosugenic action. Encoded by the human endogenous retrovirus envelope gene HERV-W, syncytin-1 trophoblast-specific expression is controlled by epigenetic mechanisms. In non-placental tissues, the syncytin-1 gene is suppressed by hypermethylation in the LTR promoter region. Hypomethylated and activated syncytin-1 gene is found in placental trophoblast lineages and malignant cells. We here demonstrate that while syncytin-1 gene remains silenced in the eutopic endometrium from endometriotic patients, syncytin-1 mRNA and protein are detected in ectopic, endometriotic lesions; particularly the endometrioid glandular endothelial cells. LINE-1 COBRA assay and immunohistochemistry using the 5-MC-specific antibody did not detect any changes in global DNA methylation in the endometriotic tissues. However, results from COBRA and bisulfite sequencing indicated that the LTR region of the syncytin-1 promoter is hypomethylated in endometriotic tissues, highlighting the significance of DNA demethylation in syncytin-1 gene activation. Analysis of DNA methyltransferase 3B (DNMT3B) mRNA levels revealed that DNMT3B3, an isoform carrying methyltransferase activity, is downregulated; whereas DNMT3B7, the isoform without enzymatic activity, is upregulated in the endometriotic tissues, pointing to positive and negative regulatory functions, respectively, of these isoforms on syncytin-1 methylation. These results have provided the first evidence supporting the involvement of epigenetic mechanisms for syncytin-1 upregulation in endometriotic tissues. Considering recent findings on the nonfusogenic activity of syncytin-1, its expression in endometriotic tissues suggests that this multifunctional protein may be implicated in the pathogenesis and/or progression of endometriosis.

Expression and Diagnostic Value of HE4 in Pancreatic Adenocarcinoma

Human epididymis protein 4 (HE4) is a recognized biomarker in ovarian and endometrial cancer and over-expressed in pancreatic adenocarcinoma. The diagnostic value of HE4 in pancreatic adenocarcinoma remains unknown. Here we elucidate mRNA, protein and serum level of HE4 in pancreatic adenocarcinoma. HE4 mRNA level in tumor adjacent tissues and pancreatic adenocarcinoma tissues were tested by real time-PCR. Tissue microarray containing normal, adenocarcinoma, and adjacent pancreatic tissue was tested by immunohistochemistry (IHC). Serum level of HE4, carbohydrate antigen 19-9 (CA19-9), carbohydrate antigen 15-3 (CA15-3) and carbohydrate antigen 125 (CA125) were detected by ELISA assay in control and tumor patients. Further we compared the sensitivity and specificity of determining HE4, CA19-9, CA15-3, and CA125 for diagnosis of pancreatic adenocarcinoma and assessed the complementary diagnostic value of HE4, CA19-9, CA15-3 and CA125. Real time PCR showed significantly increased HE4 mRNA level in pancreatic adenocarcinoma compared with control. Result of IHC showed that HE4 significantly higher expressed in the human pancreatic carcinoma tissues than in both normal and adjacent non-tumorous pancreatic tissues, and the staining intensity is inversely correlated with the clinical stage. HE4 was highly expressed in early stage of pancreatic adenocarcinoma. Serum HE4 level is higher in cases with pancreatic adenocarcinoma than in the controls. Serum HE4 levels could research to a sensitivity of 45.83% and specificity of 93.75% when the Cutoff was set at 4.59 ng/mL. The Combined HE4 and CA19-9 increased the sensitivity to 83.33%; and interestingly, the combination of HE4 with CA15-3 led to the most powerful sensitivity of 87.5%. Combined with CA19-9 and CA15-3, HE4 could be a potential biomarker to improve the diagnostic power for pancreatic adenocarcinoma.

Cytostatic and Apoptotic Effects of DNMT and HDAC Inhibitors in Endometrial Cancer Cells

DNA methyltransferase (DNMT) and histone deacetylase are key enzymes mediating the epigenetic regulation of gene expression. DNA hypermethylation and/or histone deacetylation in promoter regions is often associated with downregulation or silencing of transcription. Epigenetic silencing of tumor suppressor genes plays an important role in malignant transformation. DNMT and HDAC inhibitors induce DNA demethylation and histone acetylation, respectively, leading to reactivation of silenced genes, and dramatic morphological and functional changes in cancer cells. In this study, we have conducted a series of experiments to characterize the effects of epigenetic inhibitors in endometrial cancer cells. Using cell lines representing different stages of endometrioid cancers, we examined the impact of DNMT inhibitor, ADC, and HDAC inhibitor, TSA, on cell cycle and apoptosis. We found that while both reagents were capable of inhibiting cell proliferation and inducing cell apoptosis, TSA appeared to be a more potent apoptosis inducer, but with a smaller effect on cell cycle. On the other hand, ADC exhibited strong effects on cell cycle regulation, but had smaller impact on cell apoptosis. We subsequently confirmed the presence of a strong synergism between DNMT and HDAC inhibitors. Thus, ADC and TSA exhibited strong cytostatic and apoptotic effects in endometrial cancer cell lines and the combined application may deliver the highest response in the clinical setting.

HDAC as a Therapeutic Target for Treatment of Endometrial Cancers

Accumulating evidence suggested that epigenetic changes such as promoter-specific DNA hypermethylation and histone deacetylation cause tumor suppressor gene silencing and contribute to malignant transformation. Treatment of cancer cells with HDAC inhibitors can reactivate the expression of silenced genes, block the cell cycle, and induce cell apoptosis. In vitro experiments in cancer cell cultures and in vivo studies using mouse xynograft model have shown that HDAC inhibitors deliver potent anti-cancer effects. Clinical trials have led to approval of SAHA (Vorinostat) for treatment of lymphoma. Endometrial cancer (EC) is the most frequent malignancy in womens reproductive tract. EC is known for extensive epigenetic alterations, including overexpression of HDAC and DNMT enzymes, and the frequent epigenetic silencing of DNA repair genes such as MLH1, tumor suppressor genes PTEN, and progesterone receptor, which suggests a potentially high sensitivity of this type of cancer to HDAC inhibitors. Indeed, studies from many laboratories using various models have shown that HDAC inhibitors are promising chemotherapy reagents for endometrial cancers. This review summarizes the results from these studies, with an emphasis to provide an update on the new findings from new drugs. Background information on HDAC expression in EC, and features of HDAC inhibitors are presented based on their relevance to our focused topic. The combined application of HDAC inhibitors with radiation therapy and other conventional therapeutic reagents are also discussed.