Evidence for Converging DNA Methylation Pathways in Placenta and Cancer

N6-methyladenosine modifications in maternal-fetal crosstalk and gestational diseases

As a medium among pregnant women, environment and fetus, placenta owns powerful and delicate epigenetic processes to regulate gene expression and maintain cellular homeostasis. N6-methyladenosine (m6A) is the most prevalent modification that determines the fate of RNA, and its dynamic reversibility indicates that m6A may serve as a sensitive responder to environmental stimuli. Emerging evidence suggests that m6A modifications play an essential role in placental development and maternal-fetal crosstalk, and are closely related to gestational diseases. Herein, we summarized the latest techniques for m6A sequencing and highlighted current advances of m6A modifications in maternal-fetal crosstalk and the underlying mechanisms in gestational diseases. Therefore, proper m6A modifications are important in placental development, but its disturbance mainly caused by various environmental factors can lead to abnormal placentation and function with possible consequences of gestational diseases, fetal growth and disease susceptibility in adulthood.

Regulation of endogenous retrovirus-derived regulatory elements by GATA2/3 and MSX2 in human trophoblast stem cells

The placenta is an organ with extraordinary phenotypic diversity in eutherian mammals. Recent evidence suggests that numerous human placental enhancers are evolved from lineage-specific insertions of endogenous retroviruses (ERVs), yet the transcription factors (TFs) underlying their regulation remain largely elusive. Here, by first focusing on MER41, a primate-specific ERV family previously linked to placenta and innate immunity, we uncover the binding motifs of multiple crucial trophoblast TFs (GATA2/3, MSX2, GRHL2) in addition to innate immunity TFs STAT1 and IRF1. Integration of ChIP-seq data confirms the binding of GATA2/3, MSX2, and their related factors on the majority of MER41-derived enhancers in human trophoblast stem cells (TSCs). MER41-derived enhancers that are constitutively active in human TSCs are distinct from those activated upon interferon stimulation, which is determined by the binding of relevant TFs and their subfamily compositions. We further demonstrate that GATA2/3 and MSX2 have prevalent binding to numerous other ERV families - indicating their broad impact on ERV-derived enhancers. Functionally, the derepression of many syncytiotrophoblast genes after MSX2 knockdown is likely to be mediated by regulatory elements derived from ERVs - suggesting ERVs are also important for mediating transcriptional repression. Overall, this study characterizes the regulation of ERV-derived regulatory elements by GATA2/3, MSX2, and their cofactors in human TSCs, and provides mechanistic insights into the importance of ERVs in human trophoblast regulatory network.

Three categories of similarities between the placenta and cancer that can aid cancer treatment: Cells, the microenvironment, and metabolites

Cancer is one of the most harmful diseases, while pregnancy is a common condition of females. Placenta is the most important organ for fetal growth, which has not been fully understand. It's well known that placenta and solid tumor have some similar biological behaviors. What's more, decidua, the microenvironment of placenta, and metabolism all undergo adaptive shift for healthy pregnancy. Interestingly, decidua and the tumor microenvironment (TME); metabolism changes during pregnancy and cancer cachexia all have underlying links. However, whether the close link between pregnancy and cancer can bring some new ideas to treat cancer is still unclear. So, in this review we note that pregnancy may offer clues to treat cancer related to three categories: from cell perspective, through the shared development process of the placenta and cancer; from microenvironment perspective, though the shared features of the decidua and TME; and from metabolism perspective, through shared metabolites changes during pregnancy and cancer cachexia. Firstly, comparing gene mutations of both placenta and cancer, which is the underlying mechanism of many similar biological behaviors, helps us understand the origin of cancer and find the key factors to restore tumorigenesis. Secondly, exploring how decidua affect placenta development and similarities of decidua and TME is helpful to reshape TME, then to inhibit cancer. Thirdly, we also illustrate the possibility that the altered metabolites during pregnancy may reverse cancer cachexia. So, some key molecules changed in circulation of pregnancy may help relieve cachexia and make survival with cancer realized.

Influence of S100A2 in Human Diseases

S100 proteins are a family of low-molecular-weight proteins characterized by two calcium-binding sites with a helix-loop-helix (“EF-hand-type”) domain. The S100 family of proteins is distributed across various organs and can interact with diverse molecules. Among the proteins of the S100 family, S100 calcium-binding protein A2 (S100A2) has been identified in mammary epithelial cells, glands, lungs, kidneys, and prostate gland, exhibiting various physiological and pathological actions in human disorders, such as inflammatory diseases and malignant tumors. In this review, we introduce basic knowledge regarding S100A2 regulatory mechanisms. Although S100A2 is a tumor suppressor, we describe the various influences of S100A2 on cancer and inflammatory diseases.

A Review of Nanotechnology for Treating Dysfunctional Placenta

The placenta plays a significant role during pregnancy. Placental dysfunction contributes to major obstetric complications, such as fetal growth restriction and preeclampsia. Currently, there is no effective treatment for placental dysfunction in the perinatal period, and prophylaxis is often delivered too late, at which point the disease manifestation cannot be prevented. However, with recent integration of nanoscience and medicine to perform elaborate experiments on the human placenta, it is expected that novel and efficient nanotherapies will be developed to resolve the challenge of managing placental dysfunction. The advent of nanomedicine has enabled the safe and targeted delivery of drugs using nanoparticles. These smart nanoparticles can load the necessary therapeutic substances that specifically target the placenta, such as drugs, targeting molecules, and ligands. Packaging multifunctional molecules into specific delivery systems with high targeting ability, diagnosis, and treatment has emerged as a novel theragnostic (both therapeutic and diagnostic) approach. In this review, the authors discuss recent advances in nanotechnology for placental dysfunction treatment. In particular, the authors highlight potential candidate nanoparticle-loaded molecules that target the placenta to improve utero-placental blood flow, and reduce reactive oxygen species and oxidative stress. The authors intend to provide basic insight and understanding of placental dysfunction, potential delivery targets, and recent research on placenta-targeted nanoparticle delivery systems for the potential treatment of placental dysfunction. The authors hope that this review will sensitize the reader for continued exploration of novel nanomedicines.

Placental methylome reveals a 22q13.33 brain regulatory gene locus associated with autism

BACKGROUND

Autism spectrum disorder (ASD) involves complex genetics interacting with the perinatal environment, complicating the discovery of common genetic risk. The epigenetic layer of DNA methylation shows dynamic developmental changes and molecular memory of in utero experiences, particularly in placenta, a fetal tissue discarded at birth. However, current array-based methods to identify novel ASD risk genes lack coverage of the most structurally and epigenetically variable regions of the human genome.

RESULTS

We use whole genome bisulfite sequencing in placenta samples from prospective ASD studies to discover a previously uncharacterized ASD risk gene, LOC105373085, renamed NHIP. Out of 134 differentially methylated regions associated with ASD in placental samples, a cluster at 22q13.33 corresponds to a 118-kb hypomethylated block that replicates in two additional cohorts. Within this locus, NHIP is functionally characterized as a nuclear peptide-encoding transcript with high expression in brain, and increased expression following neuronal differentiation or hypoxia, but decreased expression in ASD placenta and brain. NHIP overexpression increases cellular proliferation and alters expression of genes regulating synapses and neurogenesis, overlapping significantly with known ASD risk genes and NHIP-associated genes in ASD brain. A common structural variant disrupting the proximity of NHIP to a fetal brain enhancer is associated with NHIP expression and methylation levels and ASD risk, demonstrating a common genetic influence.

CONCLUSIONS

Together, these results identify and initially characterize a novel environmentally responsive ASD risk gene relevant to brain development in a hitherto under-characterized region of the human genome.

Bridging Tumorigenesis and Therapy Resistance With a Non-Darwinian and Non-Lamarckian Mechanism of Adaptive Evolution

Although neo-Darwinian (and less often Lamarckian) dynamics are regularly invoked to interpret cancer's multifarious molecular profiles, they shine little light on how tumorigenesis unfolds and often fail to fully capture the frequency and breadth of resistance mechanisms. This uncertainty frames one of the most problematic gaps between science and practice in modern times. Here, we offer a theory of adaptive cancer evolution, which builds on a molecular mechanism that lies outside neo-Darwinian and Lamarckian schemes. This mechanism coherently integrates non-genetic and genetic changes, ecological and evolutionary time scales, and shifts the spotlight away from positive selection towards purifying selection, genetic drift, and the creative-disruptive power of environmental change. The surprisingly simple use-it or lose-it rationale of the proposed theory can help predict molecular dynamics during tumorigenesis. It also provides simple rules of thumb that should help improve therapeutic approaches in cancer.

The DNA methylation landscape of multiple myeloma shows extensive inter- and intrapatient heterogeneity that fuels transcriptomic variability

BACKGROUND

Cancer evolution depends on epigenetic and genetic diversity. Historically, in multiple myeloma (MM), subclonal diversity and tumor evolution have been investigated mostly from a genetic perspective.

METHODS

Here, we performed an analysis of 42 MM samples from 21 patients by using enhanced reduced representation bisulfite sequencing (eRRBS). We combined several metrics of epigenetic heterogeneity to analyze DNA methylation heterogeneity in MM patients.

RESULTS

We show that MM is characterized by the continuous accumulation of stochastic methylation at the promoters of development-related genes. High combinatorial entropy change is associated with poor outcomes in our pilot study and depends predominantly on partially methylated domains (PMDs). These PMDs, which represent the major source of inter- and intrapatient DNA methylation heterogeneity in MM, are linked to other key epigenetic aberrations, such as CpG island (CGI)/transcription start site (TSS) hypermethylation and H3K27me3 redistribution as well as 3D organization alterations. In addition, transcriptome analysis revealed that intratumor methylation heterogeneity was associated with low-level expression and high variability.

CONCLUSIONS

We propose that disrupted DNA methylation in MM is responsible for high epigenetic and transcriptomic instability allowing tumor cells to adapt to environmental changes by tapping into a pool of evolutionary trajectories.

A novel DNA methylation-based model that effectively predicts prognosis in hepatocellular carcinoma

PURPOSE

To build a novel predictive model for hepatocellular carcinoma (HCC) patients based on DNA methylation data.

METHODS

Four independent DNA methylation datasets for HCC were used to screen for common differentially methylated genes (CDMGs). Gene Ontology (GO) enrichment, and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis were used to explore the biological roles of CDMGs in HCC. Univariate Cox analysis and least absolute shrinkage and selection operator (LASSO) Cox analysis were performed to identify survival-related CDMGs (SR-CDMGs) and to build a predictive model. The importance of this model was assessed using Cox regression analysis, propensity score-matched (PSM) analysis and stratification analysis. A validation group from the Cancer Genome Atlas (TCGA) was constructed to further validate the model.

RESULTS

Four SR-CDMGs were identified and used to build the predictive model. The risk score of this model was calculated as follows: risk score = (0.01489826 × methylation level of WDR69) + (0.15868618 × methylation level of HOXB4) + (0.16674959 × methylation level of CDKL2) + (0.16689301 × methylation level of HOXA10). Kaplan-Meier analysis demonstrated that patients in the low-risk group had a significantly longer overall survival (OS; log-rank P-value =0.00071). The Cox model multivariate analysis and PSM analysis identified the risk score as an independent prognostic factor (P<0.05). Stratified analysis results further confirmed this model performed well. By analyzing the validation group, the results of receiver operating characteristic (ROC) curve analysis and survival analysis further validated this model.

CONCLUSION

Our DNA methylation-based prognosis predictive model is effective and reliable in predicting prognosis for patients with HCC.

Extensive Placental Methylation Profiling in Normal Pregnancies

The placental methylation pattern is crucial for the regulation of genes involved in trophoblast invasion and placental development, both key events for fetal growth. We investigated LINE-1 methylation and methylome profiling using a methylation EPIC array and the targeted methylation sequencing of 154 normal, full-term pregnancies, stratified by birth weight percentiles. LINE-1 methylation showed evidence of a more pronounced hypomethylation in small neonates compared with normal and large for gestational age. Genome-wide methylation, performed in two subsets of pregnancies, showed very similar methylation profiles among cord blood samples while placentae from different pregnancies appeared very variable. A unique methylation profile emerged in each placenta, which could represent the sum of adjustments that the placenta made during the pregnancy to preserve the epigenetic homeostasis of the fetus. Investigations into the 1000 most variable sites between cord blood and the placenta showed that promoters and gene bodies that are hypermethylated in the placenta are associated with blood-specific functions, whereas those that are hypomethylated belong mainly to pathways involved in cancer. These features support the functional analogies between a placenta and cancer. Our results, which provide a comprehensive analysis of DNA methylation profiling in the human placenta, suggest that its peculiar dynamicity can be relevant for understanding placental plasticity in response to the environment.

Targeting the Dysfunctional Placenta to Improve Pregnancy Outcomes Based on Lessons Learned in Cancer

In recent decades, our understanding of the disrupted mechanisms that contribute to major obstetrical diseases, including preeclampsia, fetal growth restriction, preterm birth, and gestational diabetes, has increased exponentially. Common to many of these obstetric diseases is placental maldevelopment and dysfunction; the placenta is a significant component of the maternal-fetal interface involved in coordinating, facilitating, and regulating maternal and fetal nutrient, oxygen and waste exchange, and hormone and cytokine production. Despite the advances in our understanding of placental development and function, there are currently no treatments for placental maldevelopment and dysfunction. However, given the transient nature and accessibility from the maternal circulation, the placenta offers a unique opportunity to develop targeted therapeutics for routine obstetric practices. Furthermore, given the similar developmental paradigms between the placenta and cancer, there is an opportunity to appropriate current knowledge from advances in targeted therapeutics in cancer treatments. In this review, we highlight the similarities between early placental development and cancer and introduce a number of targeted therapies currently being explored in cancer and pregnancy. We also propose a number of new effectors currently being targeted in cancer research that have the potential to be targeted in the development of treatments for pregnancy complications. Finally, we describe a method for targeting the placenta using nonviral polymers that are capable of delivering plasmids, small interfering RNA, and other effector nucleic acids, which could ultimately improve fetal and maternal outcomes from complicated pregnancies.

Epigenetic silencing of ZIC4 contributes to cancer progression in hepatocellular carcinoma

Inactivation of tumor suppressor gene played critical roles in the development and progression of human hepatocellular carcinoma (HCC). Zic family member 4 (ZIC4) is transcription factor and plays an important role in the developmental process. However, the expression and biological role of ZIC4 in HCC is poorly understood. Here, bioinformatics analysis based on The Cancer Genome Atlas (TCGA) database revealed an aberrant hypermethylation of ZIC4 in HCC. ZIC4 is frequently hypermethylated in promoter region and down expressed in HCC cells and tissues. Functionally, ZIC4 inhibition facilitated the proliferation, migration, invasion, and epithelial-mesenchymal transition (EMT) in vitro and in vivo. Conversely, ZIC4 overexpression reduced proliferation and invasiveness of HCC cells. In addition, ZIC4 inhibition rescued the antitumor effect induced by enhancer of zeste homolog 2 (EZH2) knockdown or EZH2 inhibitor. Mechanistically, EZH2 knockdown or EZH2 inhibitor reduced the enrichment of EZH2 and H3K27me3 in ZIC4 promoter region and leading to the upregulation of ZIC4. Altogether, these data indicate that epigenetic silencing of ZIC4 by EZH2 mediated H3K27me3 is an important mechanism in HCC and provide a new therapeutic target for the treatment of hepatocellular carcinoma disease.

Being Born Large for Gestational Age is Associated with Increased Global Placental DNA Methylation

Being born small (SGA) or large for gestational age (LGA) is associated with adverse birth outcomes and metabolic diseases in later life of the offspring. It is known that aberrations in growth during gestation are related to altered placental function. Placental function is regulated by epigenetic mechanisms such as DNA methylation. Several studies in recent years have demonstrated associations between altered patterns of DNA methylation and adverse birth outcomes. However, larger studies that reliably investigated global DNA methylation are lacking. The aim of this study was to characterize global placental DNA methylation in relationship to size for gestational age. Global DNA methylation was assessed in 1023 placental samples by LC-MS/MS. LGA offspring displayed significantly higher global placental DNA methylation compared to appropriate for gestational age (AGA; p < 0.001). ANCOVA analyses adjusted for known factors impacting on DNA methylation demonstrated an independent association between placental global DNA methylation and LGA births (p < 0.001). Tertile stratification according to global placental DNA methylation levels revealed a significantly higher frequency of LGA births in the third tertile. Furthermore, a multiple logistic regression analysis corrected for known factors influencing birth weight highlighted an independent positive association between global placental DNA methylation and the frequency of LGA births (p = 0.001).

A novel CpG-based signature for survival prediction of lung adenocarcinoma patients

Lung adenocarcinoma (LACA) is the leading cause of cancer-associated death worldwide. The present study intended to identify DNA methylation patterns that may serve as diagnostic and prognostic biomarkers for LACA. Data on DNA methylation and the survival data of the patients of LACA were obtained from The Cancer Genome Atlas. Kaplan-Meier curves and receiver operating characteristic curve analysis were utilized to build diagnostic and prognostic models. A total of 13 CpG sites were identified and validated as the optimal diagnostic and prognostic signature for overall survival. It was concluded that the CpG-based signature is a reliable predictor for the diagnosis and prognosis of patients with LACA.

Base-Resolution Methylome of Retinal Pigment Epithelial Cells Used in the First Trial of Human Induced Pluripotent Stem Cell-Based Autologous Transplantation

The first-in-human trial of induced pluripotent stem cell (iPSC)-based autologous transplantation was successfully performed on a female patient with age-related macular degeneration. Here we delineated the base-resolution methylome of the iPSC-derived retinal pigment epithelium (iRPE) used in this trial. The methylome of iRPE closely resembled that of native RPE (nRPE), although partially methylated domains (PMDs) emerged in iRPE but not nRPE. Most differentially methylated regions between iRPE and nRPE appeared to originate from (de)methylation errors during differentiation, whereas errors at reprogramming resulted in aberrant genomic imprinting and X chromosome reactivation. Moreover, non-CpG methylation was prominent in nRPE but not iRPE. Intriguingly, xenotransplantation to mouse remodeled the iRPE methylome to demethylate a subset of suppressed genes and accumulate non-CpG methylation, but failed to resolve PMDs and hypermethylated CpG islands. Although the impacts of these alterations remain elusive, our findings should provide a useful guide for methylome analyses of other iPSC-derived cells.

•

The methylome of iPSC-derived RPE closely resembled that of native RPE

•

Most methylomic differences originated from errors during differentiation

•

Errors at reprogramming induced loss of imprinting and X chromosome reactivation

•

Some of the differences were mitigated by xenotransplantation to mouse

Human placental methylome in the interplay of adverse placental health, environmental exposure, and pregnancy outcome

The placenta is the interface between maternal and fetal circulations, integrating maternal and fetal signals to selectively regulate nutrient, gas, and waste exchange, as well as secrete hormones. In turn, the placenta helps create the in utero environment and control fetal growth and development. The unique epigenetic profile of the human placenta likely reflects its early developmental separation from the fetus proper and its role in mediating maternal–fetal exchange that leaves it open to a range of exogenous exposures in the maternal circulation. In this review, we cover recent advances in DNA methylation in the context of placental function and development, as well as the interaction between the pregnancy and the environment.

DNA methylation-based classification and identification of renal cell carcinoma prognosis-subgroups

BACKGROUND

Renal cell carcinoma (RCC) is the most common kidney cancer and includes several molecular and histological subtypes with different clinical characteristics. The combination of DNA methylation and gene expression data can improve the classification of tumor heterogeneity, by incorporating differences at the epigenetic level and clinical features.

METHODS

In this study, we identified the prognostic methylation and constructed specific prognosis-subgroups based on the DNA methylation spectrum of RCC from the TCGA database.

RESULTS

Significant differences in DNA methylation profiles among the seven subgroups were revealed by consistent clustering using 3389 CpGs that indicated that were significant differences in prognosis. The specific DNA methylation patterns reflected differentially in the clinical index, including TNM classification, pathological grade, clinical stage, and age. In addition, 437 CpGs corresponding to 477 genes of 151 samples were identified as specific hyper/hypomethylation sites for each specific subgroup. A total of 277 and 212 genes corresponding to DNA methylation at promoter sites were enriched in transcription factor of GKLF and RREB-1, respectively. Finally, Bayesian network classifier with specific methylation sites was constructed and was used to verify the test set of prognoses into DNA methylation subgroups, which was found to be consistent with the classification results of the train set. DNA methylation-based classification can be used to identify the distinct subtypes of renal cell carcinoma.

CONCLUSIONS

This study shows that DNA methylation-based classification is highly relevant for future diagnosis and treatment of renal cell carcinoma as it identifies the prognostic value of each epigenetic subtype.

DNA hypermethylation in disease: mechanisms and clinical relevance

Increasing numbers of studies implicate abnormal DNA methylation in cancer and many non-malignant diseases. This is consistent with numerous findings about differentiation-associated changes in DNA methylation at promoters, enhancers, gene bodies, and sites that control higher-order chromatin structure. Abnormal increases or decreases in DNA methylation contribute to or are markers for cancer formation and tumour progression. Aberrant DNA methylation is also associated with neurological diseases, immunological diseases, atherosclerosis, and osteoporosis. In this review, I discuss DNA hypermethylation in disease and its interrelationships with normal development as well as proposed mechanisms for the origin of and pathogenic consequences of disease-associated hypermethylation. Disease-linked DNA hypermethylation can help drive oncogenesis partly by its effects on cancer stem cells and by the CpG island methylator phenotype (CIMP); atherosclerosis by disease-related cell transdifferentiation; autoimmune and neurological diseases through abnormal perturbations of cell memory; and diverse age-associated diseases by age-related accumulation of epigenetic alterations.

Deregulation of miR-324/KISS1/kisspeptin in early ectopic pregnancy: mechanistic findings with clinical and diagnostic implications

BACKGROUND

Ectopic pregnancy is a life-threatening condition for which novel screening tools that would enable early accurate diagnosis would improve clinical outcomes. Kisspeptins, encoded by KISS1, play an essential role in human reproduction, at least partially by regulating placental function and possibly embryo implantation. Kisspeptin levels are elevated massively in normal pregnancy and reportedly altered in various gestational pathologic diseases. Yet, the pathophysiologic role of KISS1/kisspeptin in ectopic pregnancy has not been investigated previously.

OBJECTIVE

The purpose of this study was to evaluate changes of KISS1/kisspeptin levels in ectopic pregnancy and their underlaying molecular mechanisms and to ascertain the diagnostic implications of these changes.

STUDY DESIGN

A total of 122 women with normal pregnancy who underwent voluntary termination of pregnancy and 84 patients who experienced tubal ectopic pregnancy were recruited. Measurements of plasma kisspeptins and KISS1 expression analyses in human embryonic/placental tissue were conducted in ectopic pregnancy and voluntary termination of pregnancy control subjects during the early gestational window (<12 weeks). Putative microRNA regulators of KISS1 were predicted in silico, followed by expression analyses of selected microRNAs and validation of repressive interactions in vitro. Circulating levels of these microRNAs were also assayed in ectopic pregnancy vs voluntary termination of pregnancy.

RESULTS

Circulating kisspeptins gradually increased during the first trimester of normal pregnancy but were reduced markedly in ectopic pregnancy. This profile correlated with the expression levels of KISS1 in human embryonic/placental tissue, which increased in voluntary termination of pregnancy but remained suppressed in ectopic pregnancy. Bioinformatic predictions and expression analyses identified miR-27b-3p and miR-324-3p as putative repressors of KISS1 in human embryonic/placental tissue at <12 weeks gestation, when expression of microRNAs was low in voluntary termination of pregnancy control subjects but significantly increased in ectopic pregnancy. Yet, a significant repressive interaction was documented only for miR-324-3p, occurring at the predicted 3'-UTR of KISS1. Interestingly, circulating levels of miR-324-3p, but not of miR-27b-3p, were suppressed distinctly in ectopic pregnancy, despite elevated tissue expression of the pre-microRNA. A decision-tree model that used kisspeptin and miR-324-3p levels was successful in discriminating ectopic pregnancy vs voluntary termination of pregnancy, with a receiver-operating characteristic area under the curve of 0.95±0.02 (95% confidence interval).

CONCLUSION

Our results document a significant down-regulation of KISS1/kisspeptins in early stages of ectopic pregnancy via, at least partially, a repressive interaction with miR-324-3p. Our data identify circulating kisspeptins and miR-324-3p as putative biomarkers for accurate screening of ectopic pregnancy at early gestational ages.

Association of GSTP1 and P16 promoter methylation with the risk of HBV-related hepatocellular carcinoma: a meta-analysis

Background

Study on the relationship between glutathione-S-transferase Pi 1 (GSTP1) and P16 promoter region methylation and the risk of hepatitis B virus-related hepatocellular carcinoma (HBV-related HCC) has produced inconsistent results.

Objectives

To assess the correlation between GSTP1 and P16 promoter methylation frequency and HBV-related HCC susceptibility.

Methods

All relevant studies were identified by searching PubMed, Embase, Web of Science, and China National Knowledge Infrastructure literature databases before December, 2017. The OR and the corresponding 95% CI were calculated to investigate the risk of GSTP1 and P16 promoter methylation rate and HBV-related HCC. Sensitivity analysis was performed and publication bias was estimated using the Begg’s and Egger’s test.

Results

Our meta-analysis identified the relationships of GSTP1 (six studies including 213 HBV-related HCC tumor tissues) and P16 (nine studies with 287 HBV-related HCC tumor tissue) promoter methylation with HCC risk. Compared with normal liver tissue and cirrhosis, the pooled ORs of GSTP1 promoter region methylation in HBV-related HCC cancer tissues were 6.05 (95% CI =1.20–30.52) and 5.21 (95% CI =2.19–12.41), respectively. Compared with paracancerous tissue, normal liver tissue, cirrhosis, and chronic hepatitis B as controls, the pooled ORs of P16 promoter region methylation in HBV-related HCC cancer tissues were 7.18 (95% CI =2.31–22.33), 24.89 (95% CI =3.38–183.03), 5.92 (95% CI =1.78–19.68), and 12.12 (95% CI =0.75–196.50).

Conclusion

In summary, our meta-analysis found strong associations between GSTP1 and P16 gene promoter methylation and an increased HBV-related HCC susceptibility. Moreover, GSTP1 and P16 methylation in promoter region could obviously increase the risk of HBV-related HCC in patients with cirrhosis, indicating that these would be promising biomarkers for early clinical diagnosis of HBV-related HCC.

Epigenetic silencing of SFRP5 promotes the metastasis and invasion of chondrosarcoma by expression inhibition and Wnt signaling pathway activation

BACKGROUD/AIMS

Abnormal activation of the Wnt/β-catenin signaling, which may be antagonized by the members of secreted frizzled-related proteins family (SFRPs), is implicated in tumor occurrence and development. However, the function of SFRP5 relating to Wnt/β-catenin pathway in chondrosarcoma is not clear yet. This study was undertaken to investigate the potential role of SFRP5 promoter methylation in chondrosarcoma metastasis and invasion through activating canonical Wnt signaling pathway.

METHODS AND RESULTS

The results demonstrated that SFRP5 promoter was hypermethylated and SFRP5 expression was significantly reduced in chondrosarcoma cell lines at the mRNA and protein levels. The canonical Wnt/β-catenin signaling was observably activated with β-catenin stabilization by dephosphorylation and translocation into the nuclear. 5-Aza-2'-deoxycytidine (5-Aza-dC), the DNA methyltransferase inhibitor, significantly inhibited the proliferation of chondrosarcoma cells by cell cycle arrest through repressing the methylation of SFRP5 and promoting its expression. Both 5-Aza-dC treatment and SFRP5 overexpression could significantly inhibited the metastasis and invasion of chondrosarcoma cells by inactivating Wnt/β-catenin signaling pathway and promoting chondrosarcoma cells mesenchymal-epithelial transition (MET). 5-Aza-dC also inhibited the xenograft growth and lung metastasis of chondrosarcoma cells in vivo via suppressing SFRP5 promotor methylation, inactivating Wnt/β-catenin pathway and inducing epithelial markers expression.

CONCLUSION

All of our results revealed the epigenetic silencing of SFRP5 by promoter methylation plays pivotal roles in chondrosarcoma development and metastasis through SFRP5/Wnt/β-catenin signaling axis. Modulation of their levels may serve as potential targets and diagnostic tools for novel therapeutic strategies of chondrosarcoma.