Haifeng Qiu

Upregulation of TrkB Promotes Epithelial-Mesenchymal Transition and Anoikis Resistance in Endometrial Carcinoma

Mechanisms governing the metastasis of endometrial carcinoma (EC) are poorly defined. Recent data support a role for the cell surface receptor tyrosine kinase TrkB in the progression of several human tumors. Here we present evidence for a direct role of TrkB in human EC. Immunohistochemical analysis revealed that TrkB and its secreted ligand, brain-derived neurotrophic factor (BDNF), are more highly expressed in EC than in normal endometrium. High TrkB levels correlated with lymph node metastasis (p<0.05) and lymphovascular space involvement (p<0.05) in EC. Depletion of TrkB by stable shRNA-mediated knockdown decreased the migratory and invasive capacity of cancer cell lines in vitro and resulted in anoikis in suspended cells. Conversely, exogenous expression of TrkB increased cell migration and invasion and promoted anoikis resistance in suspension culture. Furthermore, over-expression of TrkB or stimulation by BDNF resulted in altered the expression of molecular mediators of the epithelial-to-mesenchymal transition (EMT). RNA interference (RNAi)-mediated depletion of the downstream regulator, Twist, blocked TrkB-induced EMT-like transformation. The use of in vivo models revealed decreased peritoneal dissemination in TrkB-depleted EC cells. Additionally, TrkB-depleted EC cells underwent mesenchymal-to-epithelial transition and anoikis in vivo. Our data support a novel function for TrkB in promoting EMT and resistance to anoikis. Thus, TrkB may constitute a potential therapeutic target in human EC.

Epigenetic Inactivation of EFEMP1 Is Associated with Tumor Suppressive Function in Endometrial Carcinoma

Objective EFEMP1, the epidermal growth factor–containing fibulin-like extracellular matrix protein 1, functions as an oncogene or a tumor suppressor depending on the cancer types. In this study, we aim to determine whether EFEMP1 affects the tumorigenesis and progression of endometrial carcinoma. Methods The expression of EFEMP1 was investigated using immunohistochemistry in a panel of normal endometrium (n = 40), atypical hyperplasia (n = 10) and endometrial carcinoma tissues (n = 84). Methylation status of the EFEMP1 promoter was detected by methylation-specific PCR (MSP) and bisulphite genomic sequencing. Up- or down-regulation of EFEMP1 were achieved by stable or transient transfection with pCMV6/GFP/Neo-EFEMP1 or pGPU6/GFP/Neo-shEFEMP1 respectively. Effects of EFEMP1 on tumor proliferation, invasion and migration were evaluated by MTT, plate colony formation, Transwell and wound healing assay. The nude mouse tumor xenograft assay was used to investigate function of EFEMP1 in vivo. Results Compared with normal endometrium (32/40) and atypical hyperplasia (7/10), EFEMP1 expression was much lower in endometrial carcinoma tissues (16/84) (P<0.001 and P = 0.02). EFEMP1 promoter was hypermethylated in endometrial carcinoma tissues (67%) as compared to normal tissue (10%) and down-regulation of EFEMP1 was associated with promoter hypermethylation. Treatment with 5-aza-2′-deoxycytidine (5-aza-dC) and/or trichostatin A (TSA) altered EFEMP1 methylation status, and restored EFEMP1 expression. Moreover, EFEMP1 decreased secretion of MMPs and inhibited tumor cell proliferation, metastasis and invasion in vitro and suppressed tumorigenesis in nude mice. Besides, EFEMP1 increased expression of E-cadherin and suppressed expression of vimentin in endometrial carcinoma. Conclusion EFEMP1 is a new candidate tumor suppressor gene in endometrial carcinoma, and is frequently silenced by promoter hypermethylation. It could inhibit tumor growth and invasion both in vitro and in vivo. Our findings propose that targeting EFEMP1 might offer future clinical utility in endometrial carcinoma.

Elevated miR-222-3p promotes proliferation and invasion of endometrial carcinoma via targeting ERα

MicroRNAs play key roles in tumor proliferation and invasion. Here we show distinct expression of miR-222-3p between ERα-positive and ERα-negative endometrial carcinoma (EC) cell lines and primary tumors, and investigation of its relationship with ERα and other clinical parameters. In vitro, the function of miR-222-3p was examined in RL95-2 and AN3CA cell lines. MiR-222-3p expression was negatively correlated with ERα. Over-expressed miR-222-3p in RL95-2 cells promoted cell proliferation, enhanced invasiveness and induced a G1 to S phase shift in cell cycle. Furthermore, the miR-222-3p inhibitor decreased the activity of AN3CA cells to proliferate and invade. In vivo, down-regulated miR-222-3p of AN3CA cells inhibited EC tumor growth in a mouse xenograft model. Additionally, miR-222-3p increased raloxifene resistance through suppressing ERα expression in EC cells. In conclusion, miR-222-3p plays a significant role in the regulation of ERα expression and could be potential targets for restoring ERα expression and responding to antiestrogen therapy in a subset of ECs.

Forkhead-box A1 suppresses the progression of endometrial cancer via crosstalk with estrogen receptor α.

Mechanisms governing the function of Forkhead-box A1 (FOXA1), a member of the FOX class of transcription factors, have been extensively studied. However, little is known about the activities and expression pattern of FOXA1 in endometrial cancer (EC). In the present study, we investigated the level of FOXA1 in multiple human EC cell lines and clinical samples by immunohistochemistry, qRT-PCR and Western blot analysis. FOXA1 overexpression was observed in estrogen receptor (ER)α-positive EC cell lines (P=0.0048). In endometrial tissues, FOXA1 was significantly upregulated in both normal endometrium and well-differentiated endometrial cancer tissues (P<0.001). Functional analyses of FOXA1 were evaluated by MTT, plate colony formation and Transwell assay. The results revealed that forced expression of FOXA1 inhibited EC cell proliferation, whereas FOXA1 depletion promoted cell viability and was associated with tumorigenesis. The nude mouse tumor xenograft assay also confirmed that ablation of FOXA1 expression promoted cell proliferation. Furthermore, we found that knockdown of FOXA1 decreased the expression of ERα, and FOXA1 interacted with this receptor in the EC cell lines. Collectively, these experiments suggest that FOXA1 is a tumor suppressor in EC and has a possible interaction with ERα.

SHARP1 Suppresses Angiogenesis of Endometrial Cancer by Decreasing Hypoxia-Inducible Factor-1α Level

Recent data support a role for SHARP1, a basic helix-loop-helix transcription repressor, in the regulation of malignant cell behavior in several human cancers. However, the expression and role of SHARP1 during the development of endometrial cancer (EC) remain unclear. Here we show that upregulation of SHARP1 suppressed tumor angiogenesis by decreasing hypoxia-inducible factor-1α (HIF-1α), inhibited cell viability and tumor growth in EC. Immunohistochemical staining showed that the expression of SHARP1 was negatively correlated with tumor stage, histological grade, myometrial invasion, lymph node metastasis, blood vessel permeation in the myometrium and HIF-1α expression. Mechanistic studies showed that SHARP1 interacted with HIF-1α physically, and the protein level of HIF-1α and the mRNA level of its target genes (VEGFA, ANGPTL4 and CA9) were decreased by SHARP1 under hypoxia. Upregulation of SHARP1 in EC impeded hypoxia-induced angiogenesis by reducing VEGF secretion. Immunohistochemical analysis verified a correlation between decreased SHARP1 expression and increased microvessel density in EC tissues. Additionally, SHARP1 inhibited cell viability in EC cell lines. Overexpression of SHARP1 in vivo inhibited tumor growth and angiogenesis, and decreased HIF-1α expression. In this study, we established SHARP1 as a novel tumor suppressor of EC and shed light on the mechanisms by how SHARP1 inhibited EC progression. Therefore, SHARP1 may be a valuable prognostic biomarker for EC progression and shows promise as a new potential target for antiangiogenic therapeutics in human EC.

RPRD1B promotes tumor growth by accelerating the cell cycle in endometrial cancer

RPRD1B, the regulation of nuclear pre-mRNA domain containing 1B gene, functions as a cell cycle manipulator and has been found overexpressed in a small panel of endometrial cancer types. In the present study, we investigated the roles of RPRD1B in endometrial cancer using various in vitro and in vivo experiments. According to our results, RPRD1B mRNA was significantly upregulated in endometrial cancer tissues (P=0.0012). RPRD1B overexpression was correlated with tumor stage (P=0.0004), histology type (P=0.0146) and depth of myometrial invasion (P=0.024). In vitro, RPRD1B promoted cellular proliferation (P=0.032 for MTT assay and P=0.018 for colony formation assay), and accelerated the cell cycle (P=0.007) by upregulating cyclin D1, CDK4 and CDK6, while knockdown of RPRD1B suppressed cellular proliferation (P=0.02 for MTT assay and P=0.031 for colony formation assay), and led to G1 phase arrest (P=0.025) through downregulating cyclin D1, CDK4 and CDK6. Consistently, in the nude mice model, RPRD1B overexpression significantly accelerated the tumor xenograft growth (P=0.0012), accompanied by elevated Ki-67 and cyclin D1. In addition, we demonstrated that downregulating RPRD1B could sensitize Ishikawa cells to Raloxifene (P=0.01). In summary, we demonstrated that RPRD1B was frequently overexpressed in human endometrial cancer. Both in vitro and in vivo, over-abundant RPRD1B could promote tumor growth and accelerate cellular cell cycle. In addition, knockdown of RPRD1B also increased cell sensitivity to Raloxifene, making RPRD1B a potent therapeutic target for endometrial cancer, particularly in patients with resistance to the selective ER modulators.

Over-expression of platelet-derived growth factor-D promotes tumor growth and invasion in endometrial cancer.

The platelet-derived growth factor-D (PDGF-D) was demonstrated to be able to promote tumor growth and invasion in human malignancies. However, little is known about its roles in endometrial cancer. In the present study, we investigated the expression and functions of PDGF-D in human endometrial cancer. Alterations of PDGF-D mRNA and protein were determined by real time PCR, western blot and immunohistochemical staining. Up-regulation of PDGF-D was achieved by stably transfecting the pcDNA3-PDGF-D plasmids into ECC-1 cells; and knockdown of PDGF-D was achieved by transient transfection with siRNA-PDGF-D into Ishikawa cells. The MTT assay, colony formation assay and Transwell assay were used to detect the effects of PDGF-D on cellular proliferation and invasion. The xenograft assay was used to investigate the functions of PDGF-D in vivo. Compared to normal endometrium, more than 50% cancer samples showed over-expression of PDGF-D (p < 0.001), and high level of PDGF-D was correlated with late stage (p = 0.003), deep myometrium invasion (p < 0.001) and lympha vascular space invasion (p = 0.006). In vitro, over-expressing PDGF-D in ECC-1 cells significantly accelerated tumor growth and promoted cellular invasion by increasing the level of MMP2 and MMP9; while silencing PDGF-D in Ishikawa cells impaired cell proliferation and inhibited the invasion, through suppressing the expression of MMP2 and MMP9. Moreover, we also demonstrated that over-expressed PDGF-D could induce EMT and knockdown of PDGF-D blocked the EMT transition. Consistently, in xenografts assay, PDGF-D over-expression significantly promoted tumor growth and tumor weights. We demonstrated that PDGF-D was commonly over-expressed in endometrial cancer, which was associated with late stage deep myometrium invasion and lympha vascular space invasion. Both in vitro and in vivo experiments showed PDGF-D could promote tumor growth and invasion through up-regulating MMP2/9 and inducing EMT. Thus, we propose targeting PDGF-D to be a potent strategy for endometrial cancer treatment.

Suppression of the epithelial-mesenchymal transition by SHARP1 is linked to the NOTCH1 signaling pathway in metastasis of endometrial cancer

BackgroundMechanisms governing the metastasis of endometrial cancer (EC) are poorly defined. Recent data support a role for Enhancer-of-split and hairy-related protein 1 (SHARP1), a basic helix-loop-helix transcription repressor, in regulating invasiveness and angiogenesis of several human cancers. However, the role of SHARP1 in metastasis of EC remains unclear.MethodsHuman EC cell lines (Ishikawa and HEC-1B) were used. SHARP1 was upregulated by lentivirus transduction, while intracellular domain of NOTCH1 (ICN) were upregulated by transient transfection with plasmids. Effects of SHARP1 on cell migration and invasion were evaluated by wound healing assay and transwell invasion assay. Experimental metastasis assay were performed in nude mice. Effects of SHAPR1 on protein levels of target genes were detected by western blotting. Furthermore, the association between SHARP1 and the NOTCH1/EMT pathway was further verified in EC tissue specimens by immunohistochemical analysis.ResultsOverexpression of SHARP1 in EC cells inhibited cell migration, invasion, and metastasis. Exogenous SHARP1 overexpression affected the proteins levels of genes involved in EMT process and NOTCH1 signaling pathway. Upregulation of ICN in SHARP1-overexpressing Ishikawa cells induced cell migration and an EMT phenotype. Additionally, immunohistochemical analysis demonstrated that SHARP1 protein levels were lower in metastatic EC than in primary tumors, and statistical analysis revealed correlations between levels of SHARP1 and markers of EMT and NOTCH1 signaling pathway in human EC tissue specimen.ConclusionsThis work supports a role for SHARP1 in suppressing EMT and metastasis in EC by attenuating NOTCH1 signaling. Therefore, SHARP1 may be a novel marker for lymphatic metastasis in EC patients.

EFEMP1 is repressed by estrogen and inhibits the epithelial-mesenchymal transition via Wnt/β-catenin signaling in endometrial carcinoma

Epidermal growth factor-containing fibulin-like extracellular matrix protein 1 (EFEMP1) acted as a tumor suppressor in endometrial carcinoma (EC). However, the correlation between EFEMP1 and estrogen is unknown. Here, we reported that the expression of EFEMP1 was conversely associated with ERα in endometrial carcinoma tissues. In endometrial carcinoma cells, estrogen/ERα signaling significantly suppressed the expression of EFEMP1. Moreover, chromatin immunoprecipitation (CHIP) and dual-luciferase reporter assays demonstrate that estrogen/ERα bound to the estrogen response element (ERE) located in EFEMP1 promoter and repressed its expression. Besides, in vitro and in vivo, EFEMP1 could remarkably suppress the expression of epithelial-mesenchymal transition (EMT) markers such as Vimentin, Snail and the Wnt/β-catenin target genes like Cyclin-D1 and c-Myc, which could be restored when EFEMP1 was silenced. In addition, XAV93920 (the inhibitor of the Wnt/β-catenin pathway) blocked and LiCl (the activator of the Wnt/β-catenin pathway) enhanced the effect of EFEMP1 on EMT. In conclusion, we demonstrated that estrogen/ERα signal suppresses EFEMP1. Besides, EFEMP1 inhibits EMT via interfering the Wnt/β-catenin signaling.

EMX2 is downregulated in endometrial cancer and correlated with tumor progression

EMX2 (the human homologue of Drosophila empty spiracles gene 2) is a candidate tumor suppressor. However, its roles in endometrial cancer are still unknown. In this study, we evaluated EMX2 expression in different subtypes of endometrial cancer and its relationships with clinicopathologic characteristics. By immunohistochemical staining, we investigated the level of EMX2 protein in 122 endometrial cancer and 25 normal endometrium tissues. Correlations between EMX2 expression and clinicopathologic features of patients were analyzed using a statistical software. Compared with the normal endometrium, the expression of EMX2 was significantly downregulated in endometrial cancer tissues (P<0.001). Reduced EMX2 expression was correlated with the tumor stage (P=0.023), grade (P=0.016), and the depth of myometrial invasion (P=0.04), but not with age, pathologic subtype, lymph node metastasis, lymph vascular space invasion, or ER/PR/p53 status. Downregulation of EMX2 was associated with tumor progression and may be a critical factor in the carcinogenesis and progression of endometrial cancer, which provided a novel therapeutic target and a potential marker for prognostic prediction.