D-glucuronyl C5-epimerase suppresses small-cell lung cancer cell proliferation in vitro and tumour growth in vivo

Glycolysis-Metabolism-Related Prognostic Signature for Ewing Sarcoma Patients

Ewing sarcoma (EwS) is a malignant sarcoma which occurs in bone and soft tissues commonly happening in children with poor survival rates. Changes in cell metabolism, such as glycolysis, may provide the environment for the transformation and progression of tumors. We aimed to build a model to predict prognosis of EwS patients based on glycolysis and metabolism genes. Candidate genes were obtained by differential gene expression analysis based on GSE17679, GSE17674 and ICGC datasets. We performed GO and KEGG pathway enrichment analysis on candidate genes. Univariate Cox and LASSO Cox regression analyses were conducted to construct a model to calculate the Risk Score. GSEA was done between high-risk and low-risk groups. CIBERSORT was applied to analyze the immune landscape. We got 295 candidate glycolysis-metabolism-related genes which were enriched in 620 GO terms and 18 KEGG pathways. 12 Genes were selected by univariate Cox model and 5 of them were determined by LASSO Cox regression analysis to be used in the construction of the Risk Score model. The Risk Score could be considered as an independent prognosis factor. The immune landscape and immune checkpoints' expression significantly differed between high- and low-risk groups. Our research constructed a new glycolysis-metabolism-related genes (FABP5, EMILIN1, GLCE, PHF11 and PALM3) based prognostic signature for EwS patients and assisted in gaining insight into prognosis to improve therapies further.

Prognostic value of GLCE and infiltrating immune cells in Ewing sarcoma

Background

The prognostic value of D-glucuronyl C5-epimerase (GLCE) and mast cell infiltration in Ewing sarcoma (ES) has not been well specified and highlighted, which may facilitate survival prediction and treatment.

Methods

Several qualified datasets were downloaded from the GEO website. Common differentially expressed genes between normal subjects and ES patients in GSE17679, GSE45544, and GSE68776 were identified and screened by multiple algorithms to find hub genes with prognostic value. The prognostic value of 64 infiltrating cells was also explored. A prognostic model was established and then validated with GSE63155 and GSE63156. Finally, functional analysis was performed.

Results

GLCE and mast cell infiltration were screened as two indicators for a prognostic model. The Kaplan‒Meier analysis showed that patients in the low GLCE expression, mast cell infiltration and risk score groups had poorer outcomes than patients in the high GLCE expression, mast cell infiltration and risk score groups, both in the training and validation sets. Scatter plots and heatmaps also indicated the same results. The concordance indices and calibration analyses indicated a high prediction accuracy of the model in the training and validation sets. The time-dependent receiver operating characteristic analyses suggested high sensitivity and specificity of the model, with area under the curve values between 0.76 and 0.98. The decision curve analyses suggested a significantly higher net benefit by the model than the treat-all and treat-none strategies. Functional analyses suggested that glycosaminoglycan biosynthesis-heparan sulfate/heparin, the cell cycle and microRNAs in cancer were upregulated in ES patients.

Conclusions

GLCE and mast cell infiltration are potential prognostic indicators in ES. GLCE may affect the proliferation, angiogenesis and metastasis of ES by affecting the biosynthesis of heparan sulfate and heparin.

Generation, evolution, interfering factors, applications, and challenges of patient-derived xenograft models in immunodeficient mice

Establishing appropriate preclinical models is essential for cancer research. Evidence suggests that cancer is a highly heterogeneous disease. This follows the growing use of cancer models in cancer research to avoid these differences between xenograft tumor models and patient tumors. In recent years, a patient-derived xenograft (PDX) tumor model has been actively generated and applied, which preserves both cell-cell interactions and the microenvironment of tumors by directly transplanting cancer tissue from tumors into immunodeficient mice. In addition to this, the advent of alternative hosts, such as zebrafish hosts, or in vitro models (organoids and microfluidics), has also facilitated the advancement of cancer research. However, they still have a long way to go before they become reliable models. The development of immunodeficient mice has enabled PDX to become more mature and radiate new vitality. As one of the most reliable and standard preclinical models, the PDX model in immunodeficient mice (PDX-IM) exerts important effects in drug screening, biomarker development, personalized medicine, co-clinical trials, and immunotherapy. Here, we focus on the development procedures and application of PDX-IM in detail, summarize the implications that the evolution of immunodeficient mice has brought to PDX-IM, and cover the key issues in developing PDX-IM in preclinical studies.

Heparan sulfate proteoglycans in cancer: Pathogenesis and therapeutic potential

The heparan sulfate proteoglycans (HSPGs) are glycoproteins that consist of a proteoglycan "core" protein and covalently attached heparan sulfate (HS) chain. HSPGs are ubiquitously expressed in mammalian cells on the cell surface and in the extracellular matrix (ECM) and secretory vesicles. Within HSPGs, the protein cores determine when and where HSPG expression takes place, and the HS chains mediate most of HSPG's biological roles through binding various protein ligands, including cytokines, chemokines, growth factors and receptors, morphogens, proteases, protease inhibitors, and ECM proteins. Through these interactions, HSPGs modulate cell proliferation, adhesion, migration, invasion, and angiogenesis to display essential functions in physiology and pathology. Under physiological conditions, the expression and localization of HSPGs are finely regulated to orchestrate their physiological functions, and this is disrupted in cancer. The HSPG dysregulation elicits multiple oncogenic signaling, including growth factor signaling, ECM and Integrin signaling, chemokine and immune signaling, cancer stem cell, cell differentiation, apoptosis, and senescence, to prompt cell transformation, proliferation, tumor invasion and metastasis, tumor angiogenesis and inflammation, and immunotolerance. These oncogenic roles make HSPGs an attractive pharmacological target for anti-cancer therapy. Several therapeutic strategies have been under development, including anti-HSPG antibodies, peptides and HS mimetics, synthetic xylosides, and heparinase inhibitors, and shown promising anti-cancer efficacy. Therefore, much progress has been made in this line of study. However, it needs to bear in mind that the roles of HSPGs in cancer can be either oncogenic or tumor-suppressive, depending on the HSPG and the cancer cell type with the underlying mechanisms that remain obscure. Further studies need to address these to fill the knowledge gap and rationalize more efficient therapeutic targeting.

LINC01089, suppressed by YY1, inhibits lung cancer progression by targeting miR-301b-3p/HPDG axis

PURPOSE

LINC01089 is a newly identified lncRNA and rarely reported in human cancers. Our study aimed to investigate its role in lung cancer.

METHODS

YY1, LINC01089, and miR-301b-3p levels in lung cancer tissues and cells were assessed using qRT-PCR. Bioinformatics analysis and luciferase reporter, ChIP, and RIP assays were carried out for determining the relationships among YY1, LINC01089, miR-301b-3p, and HPGD. Gain- and loss-of-function assays were carried out to confirm the impacts of LINC01089 and HPDG in lung cancer cells. CCK-8 assay was used to assess cell proliferation rate, and Transwell assay was applied to measure cell invasion and migration. An in vivo tumor model was applied for validating the role of LINC01089.

RESULTS

LINC01089 was decreased in lung cancer tissues and cells, and low LINC01089 level predicted a poor clinical outcome. YY1 directly bound to LINC01089 promoter region and inhibited its transcription. LINC01089 knockdown thwarted the proliferation, invasion, and migration capacity of H1299 and A549 cells and aggravated tumor growth. Specifically, LINC01089 functioned as a competing endogenous RNA of miR-301b-3p to modulate HPGD and thereby affected lung cancer progression.

CONCLUSION

Our data revealed that LINC01089, directly suppressed by YY1, inhibited lung cancer progression by targeting the miR-301b-3p/HPGD axis. Graphical abstract 1. LINC01089 expression was downregulated in lung cancer tisuues and cell lines, and low LINC01089 levels predicted a poor clinical outcome. 2. LINC01089 knockdown enhanced proliferation, invasion, and migration of H1299 and A549 cells in vitro and promoted lung cancer cell tumorigenesis and metastasis in vivo. 3. LINC01089, directly suppressed by YY1, functioned as a competing endogenous RNA against miR-301b-3p to increase HPGD expression.

Heparan Sulfate Biosynthesis and Sulfation Profiles as Modulators of Cancer Signalling and Progression

Heparan Sulfate Proteoglycans (HSPGs) are important cell surface and Extracellular Matrix (ECM) maestros involved in the orchestration of multiple cellular events in physiology and pathology. These glycoconjugates bind to various bioactive proteins via their Heparan Sulfate (HS) chains, but also through the protein backbone, and function as scaffolds for protein-protein interactions, modulating extracellular ligand gradients, cell signalling networks and cell-cell/cell-ECM interactions. The structural features of HS chains, including length and sulfation patterns, are crucial for the biological roles displayed by HSPGs, as these features determine HS chains binding affinities and selectivity. The large HS structural diversity results from a tightly controlled biosynthetic pathway that is differently regulated in different organs, stages of development and pathologies, including cancer. This review addresses the regulatory mechanisms underlying HS biosynthesis, with a particular focus on the catalytic activity of the enzymes responsible for HS glycan sequences and sulfation motifs, namely D-Glucuronyl C5-Epimerase, N- and O-Sulfotransferases. Moreover, we provide insights on the impact of different HS structural epitopes over HSPG-protein interactions and cell signalling, as well as on the effects of deregulated expression of HS modifying enzymes in the development and progression of cancer. Finally, we discuss the clinical potential of HS biosynthetic enzymes as novel targets for therapy, and highlight the importance of developing new HS-based tools for better patients' stratification and cancer treatment.

Glycolysis- and immune-related novel prognostic biomarkers of Ewing's sarcoma: glucuronic acid epimerase and triosephosphate isomerase 1

INTRODUCTION

Owing to the poor prognosis of Ewing's sarcoma, reliable prognostic biomarkers are highly warranted for clinical diagnosis of the disease.

MATERIALS AND METHODS

A combination of the weighted correlation network analysis and differentially expression analysis was used for initial screening; glycolysis-related genes were extracted and subjected to univariate Cox, LASSO regression, and multivariate Cox analyses to construct prognostic models. The immune cell composition of each sample was analysed using CIBERSORT software. Immunohistochemical analysis was performed for assessing the differential expression of modelled genes in Ewing's sarcoma and paraneoplastic tissues.

RESULTS

A logistic regression model constructed for the prognosis of Ewing's sarcoma exhibited that the patient survival rate in the high-risk group is much lower than in the low-risk group. CIBERSORT analysis exhibited a strong correlation of Ewing's sarcoma with naïve B cells, CD8⁺ T cells, activated NK cells, and M0 macrophages (P < 0.05). Immunohistochemical analysis confirmed the study findings.

CONCLUSIONS

GLCE and TPI1 can be used as prognostic biomarkers to predict the prognosis of Ewing's sarcoma, and a close association of Ewing's sarcoma with naïve B cells, CD8⁺ T cells, activated NK cells, and M0 macrophages provides a novel approach to the disease immunotherapy.

Heparan Sulfate Proteoglycan Signaling in Tumor Microenvironment

In the last few decades, heparan sulfate (HS) proteoglycans (HSPGs) have been an intriguing subject of study for their complex structural characteristics, their finely regulated biosynthetic machinery, and the wide range of functions they perform in living organisms from development to adulthood. From these studies, key roles of HSPGs in tumor initiation and progression have emerged, so that they are currently being explored as potential biomarkers and therapeutic targets for cancers. The multifaceted nature of HSPG structure/activity translates in their capacity to act either as inhibitors or promoters of tumor growth and invasion depending on the tumor type. Deregulation of HSPGs resulting in malignancy may be due to either their abnormal expression levels or changes in their structure and functions as a result of the altered activity of their biosynthetic or remodeling enzymes. Indeed, in the tumor microenvironment, HSPGs undergo structural alterations, through the shedding of proteoglycan ectodomain from the cell surface or the fragmentation and/or desulfation of HS chains, affecting HSPG function with significant impact on the molecular interactions between cancer cells and their microenvironment, and tumor cell behavior. Here, we overview the structural and functional features of HSPGs and their signaling in the tumor environment which contributes to tumorigenesis and cancer progression.

Nine glycolysis-related gene signature predicting the survival of patients with endometrial adenocarcinoma

Background

Endometrial cancer is the fourth most common cancer in women. The death rate for endometrial cancer has increased. Glycolysis of cellular respiration is a complex reaction and is the first step in most carbohydrate catabolism, which was proved to participate in tumors.

Methods

We analyzed the sample data of over 500 patients from TCGA database. The bioinformatic analysis included GSEA, cox and lasso regression analysis to select prognostic genes, as well as construction of a prognostic model and a nomogram for OS evaluation. The immunohistochemistry staining, survival analysis and expression level validation were also performed. Maftools package was for mutation analysis. GSEA identified Glycolysis was the most related pathway to EC. qRT-PCR verified the expression level of hub gene in clinical samples.

Results

According to the prognostic model using the train set, 9 glycolysis-related genes including B3GALT6, PAM, LCT, GMPPB, GLCE, DCN, CAPN5, GYS2 and FBP2 were identified as prognosis-related genes. Based on nine gene signature, the EC patients could be classified into high and low risk subgroups, and patients with high risk score showed shorter survival time. Time-dependent ROC analysis and Cox regression suggested that the risk score predicted EC prognosis accurately and independently. Analysis of test and train sets yielded consistent results A nomogram which incorporated the 9-mRNA signature and clinical features was also built for prognostic prediction. Immunohistochemistry staining and TCGA validation showed that expression levels of these genes do differ between EC and normal tissue samples. GSEA revealed that the samples of the low-risk group were mainly concentrated on Bile Acid Metabolism. Patients in the low-risk group displayed obvious mutation signatures compared with those in the high-risk group. The expression levels of B3GALT6, DCN, FBP2 and GYS2 are lower in tumor samples and higher in normal tissue samples. The expression of CAPN5 and LCT in clinical sample tissues is just the opposite.

Conclusion

This study found that the Glycolysis pathway is associated with EC and screened for hub genes on the Glycolysis pathway, which may serve as new target for the treatment of EC.

Epigenetic Regulation of the Biosynthesis & Enzymatic Modification of Heparan Sulfate Proteoglycans: Implications for Tumorigenesis and Cancer Biomarkers

Emerging evidence suggests that the enzymes in the biosynthetic pathway for the synthesis of heparan sulfate moieties of heparan sulfate proteoglycans (HSPGs) are epigenetically regulated at many levels. As the exact composition of the heparan sulfate portion of the resulting HSPG molecules is critical to the broad spectrum of biological processes involved in oncogenesis, the epigenetic regulation of heparan sulfate biosynthesis has far-reaching effects on many cellular activities related to cancer progression. Given the current focus on developing new anti-cancer therapeutics focused on epigenetic targets, it is important to understand the effects that these emerging therapeutics may have on the synthesis of HSPGs as alterations in HSPG composition may have profound and unanticipated effects. As an introduction, this review will briefly summarize the variety of important roles which HSPGs play in a wide-spectrum of cancer-related cellular and physiological functions and then describe the biosynthesis of the heparan sulfate chains of HSPGs, including how alterations observed in cancer cells serve as potential biomarkers. This review will then focus on detailing the multiple levels of epigenetic regulation of the enzymes in the heparan sulfate synthesis pathway with a particular focus on regulation by miRNA and effects of epigenetic therapies on HSPGs. We will also explore the use of lectins to detect differences in heparan sulfate composition and preview their potential diagnostic and prognostic use in the clinic.

Tissue-specificity of heparan sulfate biosynthetic machinery in cancer

Heparan sulfate (HS) proteoglycans are key components of cell microenvironment and fine structure of their polysaccharide HS chains plays an important role in cell-cell interactions, adhesion, migration and signaling. It is formed on non-template basis, so, structure and functional activity of HS biosynthetic machinery is crucial for correct HS biosynthesis and post-synthetic modification. To reveal cancer-related changes in transcriptional pattern of HS biosynthetic system, the expression of HS metabolism-involved genes (EXT1/2, NDST1/2, GLCE, 3OST1/HS3ST1, SULF1/2, HPSE) in human normal (fibroblasts, PNT2) and cancer (MCF7, LNCaP, PC3, DU145, H157, H647, A549, U2020, U87, HT116, KRC/Y) cell lines and breast, prostate, colon tumors was studied. Real-time RT-PCR and Western-blot analyses revealed specific transcriptional patterns and expression levels of HS biosynthetic system both in different cell lines in vitro and cancers in vivo. Balance between transcriptional activities of elongation- and post-synthetic modification- involved genes was suggested as most informative parameter for HS biosynthetic machinery characterization. Normal human fibroblasts showed elongation-oriented HS biosynthesis, while PNT2 prostate epithelial cells had modification-oriented one. However, cancer epithelial cells demonstrated common tendency to acquire fibroblast-like elongation-oriented mode of HS biosynthetic system. Surprisingly, aggressive metastatic cancer cells (U2020, DU145, KRC/Y) retained modification-oriented HS biosynthesis similar to normal PNT2 cells, possibly enabling the cells to keep like-to-normal cell surface glycosylation pattern to escape antimetastatic control. The obtained results show the cell type-specific changes of HS-biosynthetic machinery in cancer cells in vitro and tissue-specific changes in different cancers in vivo, supporting a close involvement of HS biosynthetic system in carcinogenesis.

Structural and functional study of D-glucuronyl C5-epimerase

Heparan sulfate (HS) is a glycosaminoglycan present on the cell surface and in the extracellular matrix, which interacts with diverse signal molecules and is essential for many physiological processes including embryonic development, cell growth, inflammation, and blood coagulation. D-glucuronyl C5-epimerase (Glce) is a crucial enzyme in HS synthesis, converting D-glucuronic acid to L-iduronic acid to increase HS flexibility. This modification of HS is important for protein ligand recognition. We have determined the crystal structures of Glce in apo-form (unliganded) and in complex with heparin hexasaccharide (product of Glce following O-sulfation), both in a stable dimer conformation. A Glce dimer contains two catalytic sites, each at a positively charged cleft in C-terminal α-helical domains binding one negatively charged hexasaccharide. Based on the structural and mutagenesis studies, three tyrosine residues, Tyr(468), Tyr(528), and Tyr(546), in the active site were found to be crucial for the enzymatic activity. The complex structure also reveals the mechanism of product inhibition (i.e. 2-O- and 6-O-sulfation of HS keeps the C5 carbon of L-iduronic acid away from the active-site tyrosine residues). Our structural and functional data advance understanding of the key modification in HS biosynthesis.

Matrigel: from discovery and ECM mimicry to assays and models for cancer research

The basement membrane is an important extracellular matrix that is found in all epithelial and endothelial tissues. It maintains tissue integrity, serves as a barrier to cells and to molecules, separates different tissue types, transduces mechanical signals, and has many biological functions that help to maintain tissue specificity. A well-defined soluble basement membrane extract, termed BME/Matrigel, prepared from an epithelial tumor is similar in content to authentic basement membrane, and forms a hydrogel at 24-37°C. It is used in vitro as a substrate for 3D cell culture, in suspension for spheroid culture, and for various assays, such as angiogenesis, invasion, and dormancy. In vivo, BME/Matrigel is used for angiogenesis assays and to promote xenograft and patient-derived biopsy take and growth. Studies have shown that both the stiffness of the BME/Matrigel and its components (i.e. chemical signals) are responsible for its activity with so many different cell types. BME/Matrigel has widespread use in assays and in models that improve our understanding of tumor biology and help define therapeutic approaches.

Transcriptional Activity of Heparan Sulfate Biosynthetic Machinery is Specifically Impaired in Benign Prostate Hyperplasia and Prostate Cancer

Heparan sulfates (HSs) are key components of mammalian cells surface and extracellular matrix. Structure and composition of HS, generated by HS-biosynthetic system through non-template-driven process, are significantly altered in cancer tissues. The aim of this study was to investigate the involvement of HS-metabolic machinery in prostate carcinogenesis. Transcriptional patterns of HS-metabolic enzymes (EXT1, EXT2, NDST1, NDST2, GLCE, 3OST1/HS3ST1, SULF1, SULF2, HPSE) were determined in normal, benign, and cancer human prostate tissues and cell lines (PNT2, LNCaP, PC3, DU145). Stability of the HS-metabolic system patterns under the pressure of external or internal stimuli was studied. Overall impairment of transcriptional activity of HS-metabolic machinery was detected in benign prostate hyperplasia, while both significant decrease in the transcriptional activity and changes in the expression patterns of HS metabolism-involved genes were observed in prostate tumors. Prostate cancer cell lines possessed specific transcriptional patterns of HS metabolism-involved genes; however, expression activity of the system was similar to that of normal prostate PNT2 cells. HS-metabolic system was able to dynamically react to different external or internal stimuli in a cell type-dependent manner. LNCaP cells were sensitive to the external stimuli (5-aza-deoxycytidin or Trichostatin A treatments; co-cultivation with human fibroblasts), whereas PC3 cells almost did not respond to the treatments. Ectopic GLCE over-expression resulted in transcriptional activation of HS-biosynthetic machinery in both cell lines, suggesting an existence of a self-regulating mechanism for the coordinated transcription of HS metabolism-involved genes. Taken together, these findings demonstrate impairment of HS-metabolic system in prostate tumors in vivo but not in prostate cancer cells in vitro, and suggest that as a potential microenvironmental biomarker for prostate cancer diagnostics and treatment.

GLCE regulates PC12 cell neuritogenesis induced by nerve growth factor through activating SMAD/ID3 signalling

Depletion of glucuronic acid epimerase causes arrested PC12 cell growth and promotes the neuritogenesis and differentiation induced by nerve growth factor through activating SMAD/ID3 signalling. This action is independent of its enzymatic activity.

D-glucuronyl C5-epimerase cell type specifically affects angiogenesis pathway in different prostate cancer cells

D-glucuronyl C5-epimerase (GLCE) is involved in breast and lung carcinogenesis as a potential tumor suppressor gene, acting through inhibition of tumor angiogenesis and invasion/metastasis pathways. However, in prostate tumors, increased GLCE expression is associated with advanced disease, suggesting versatile effects of GLCE in different cancers. To investigate further the potential cancer-promoting effect of GLCE in prostate cancer, GLCE was ectopically re-expressed in morphologically different LNCaP and PC3 prostate cancer cells. Transcriptional profiles of normal PNT2 prostate cells, LNCaP, PC3 and DU145 prostate cancer cells, and GLCE-expressing LNCaP and PC3 cells were determined. Comparative analysis revealed the genes whose expression was changed in prostate cancer cells compared with normal PNT2 cells, and those differently expressed between the cancer cell lines (ACTA2, IL6, SERPINE1, TAGLN, SEMA3A, and CDH2). GLCE re-expression influenced mainly angiogenesis-involved genes (ANGPT1, SERPINE1, IGF1, PDGFB, TNF, IL8, TEK, IFNA1, and IFNB1) but in a cell type-specific manner (from basic deregulation of angiogenesis in LNCaP cells to significant activation in PC3 cells). Invasion/metastasis pathway was also affected (MMP1, MMP2, MMP9, S100A4, ITGA1, ITGB3, ERBB2, and FAS). The obtained results suggest activation of angiogenesis as a main molecular mechanism of pro-oncogenic effect of GLCE in prostate cancer. GLCE up-regulation plus expression pattern of a panel of six genes, discriminating morphologically different prostate cancer cell sub-types, is suggested as a potential marker of aggressive prostate cancer.

Heterogeneity of d-glucuronyl C5-epimerase expression and epigenetic regulation in prostate cancer

Heparansulfate proteoglycans (HSPG) play an important role in cell–cell and cell–matrix interactions and signaling, and one of the key enzymes in heparansulfate biosynthesis is d-glucuronyl C5-epimerase (GLCE). A tumor suppressor function has been demonstrated for GLCE in breast and lung carcinogenesis; however, no data are available as to the expression and regulation of the gene in prostate cancer. In this study, decreased GLCE expression was observed in 10% of benign prostate hyperplasia (BPH) tissues and 53% of prostate tumors, and increased GLCE mRNA levels were detected in 49% of BPH tissues and 21% of tumors. Statistical analysis showed a positive correlation between increased GLCE expression and Gleason score, TNM staging, and prostate-specific antigen (PSA) level in the prostate tumors (Pearson correlation coefficients GLCE/Gleason = 0.56, P < 0.05; GLCE/TNM = 0.62, P < 0.05; and GLCE/PSA = 0.88, P < 0.01), suggesting GLCE as a candidate molecular marker for advanced prostate cancer. Immunohistochemical analysis revealed an intratumoral heterogeneity of GLCE protein levels both in BPH and prostate cancer cells, resulting in a mixed population of GLCE-expressing and nonexpressing epithelial cells in vivo. A model experiment on normal (PNT2) and prostate cancer (LNCaP, PC3, DU145) cell lines in vitro showed a 1.5- to 2.5-fold difference in GLCE expression levels between the cancer cell lines and an overall decrease in GLCE expression in cancer cells. Methyl-specific polymerase chain reaction (PCR), bisulfite sequencing, and deoxy-azacytidin (aza-dC) treatment identified differential GLCE promoter methylation (LNCaP 70–72%, PC3 32–35%, DU145, and PNT2 no methylation), which seems to contribute to heterogeneous GLCE expression in prostate tumors. The obtained results reveal the complex deregulation of GLCE expression in prostatic diseases compared with normal prostate tissue and suggest that GLCE may be used as a potential model to study the functional role of intratumor cell heterogeneity in prostate cancer progression.

The molecular mechanisms of intratumour heterogeneity of cancer cells, contributing to tissue malignisation, remain unclear. This study reveals the complex deregulation of d-glucuronyl C5-epimerase (GLCE) expression in benign prostatic hyperplasia and prostate tumours, and the high intratumour heterogeneity of prostate cancer cells in terms of GLCE expression and promoter methylation. The results suggest that GLCE may be used as a potential target gene to study the functional role of cancer cell heterogeneity in disease progression and treatment.

miRNA-218 contributes to the regulation of D-glucuronyl C5-epimerase expression in normal and tumor breast tissues

microRNAs (miRNAs) are key posttranscriptional regulators of gene expression. In the present study, regulation of tumor-suppressor gene D-glucuronyl C5-epimerase (GLCE) by miRNA-218 was investigated. Significant downregulation of miRNA-218 expression was shown in primary breast tumors. Exogenous miRNA-218/anti-miRNA-218 did not affect GLCE mRNA but regulated GLCE protein level in MCF7 breast carcinoma cells in vitro. Comparative analysis showed a positive correlation between miRNA-218 and GLCE mRNA, and negative correlation between miRNA-218 and GLCE protein levels in breast tissues and primary tumors in vivo, supporting a direct involvement of miRNA-218 in posttranscriptional regulation of GLCE in human breast tissue. A common scheme for the regulation of GLCE expression in normal and tumor breast tissues is suggested.

The TCF4/β-catenin pathway and chromatin structure cooperate to regulate D-glucuronyl C5-epimerase expression in breast cancer

D-glucuronyl C5-epimerase (GLCE) is a potential tumor-suppressor gene involved in heparan sulfate biosynthesis. GLCE expression is significantly decreased in breast tumors; however, the underlying molecular mechanisms remain unclear. This study examined the possible epigenetic mechanisms for GLCE inactivation in breast cancer. Very little methylation of the GLCE promoter region was detected in breast tumors in vivo and in breast cancer cells (MCF7 and T47D) in vitro and GLCE expression in breast cancer cells was not altered by 5-deoxyazacytidine (5-aza-dC) treatment, suggesting that promoter methylation is not involved in regulating GLCE expression. Chromatin activation by Trichostatin A (TSA) or 5-aza-dC/TSA treatment increased GLCE expression by two to 3-fold due to an increased interaction between the GLCE promoter and the TCF4/β-catenin transactivation complex, or H3K9ac and H3K4Me3 histone modifications. However, ectopic expression of TCF4/β-catenin was not sufficient to activate GLCE expression in MCF7 cells, suggesting that chromatin structure plays a key role in GLCE regulation. Although TSA treatment significantly repressed canonical WNT signaling in MCF7 cells, it did not influence endogenous TCF4/β-catenin mRNA levels and activated TCF4/β-catenin-driven transcription from the GLCE promoter, indicating GLCE as a novel target for TCF4/β-catenin complex in breast cancer cells. A correlation was observed between GLCE, TCF4 and β-catenin expression in breast cancer cells and primary tumors, suggesting an important role for TCF4/β-catenin in regulating GLCE expression both in vitro and in vivo. Taken together, the results indicate that GLCE expression in breast cancer is regulated by a combination of chromatin structure and TCF4/β-catenin complex activity.