Epigenetics of SFRP1: The Dual Roles in Human Cancers

Transcription factor FOXC1 positively regulates SFRP1 expression in androgenetic alopecia

Androgenetic alopecia (AGA) is the most common type of hair loss dysfunction. Secreted frizzled related protein 1 (SFRP1) is found to be associated with hair loss, but its role in AGA and the regulation mechanism of its transcription level is unclear. The aim of our study is to explore the expression of SFRP1 in AGA samples and its transcriptional mechanism. Male frontal and occipital scalp hair follicles from AGA patients were collected, and human dermal papilla cells (DPCs) were isolated and cultured. SFRP1 gene was cloned and constructed into recombinant plasmids to perform dual-luciferase reporter assay. Transcription factor binding sites were predicted through the Jaspar website and further confirmed by the chromatin immunoprecipitation (ChIP) assay. Expression of genes in DPCs was determined by immunofluorescence (IF) staining, quantitative real-time PCR (qRT-PCR) and western blotting. Our findings showed that SFRP1 was highly expressed in DPCs of AGA patients. The core promoter region of SFRP1 was from -100 to +50 bp and was found to be positively regulated by forkhead box C1 (FOXC1), a transcription factor related to hair growth, both at mRNA and protein level in DPCs. Our study suggests that FOXC1 plays an important role in regulating SFRP1 transcription, which may provide new insights into the development of therapeutic strategies for the treatment of AGA.

Microsatellite Instability in Colorectal Cancer Liquid Biopsy-Current Updates on Its Potential in Non-Invasive Detection, Prognosis and as a Predictive Marker

Colorectal cancer (CRC) is the third most commonly-diagnosed cancer in the world and ranked second for cancer-related mortality in humans. Microsatellite instability (MSI) is an indicator for Lynch syndrome (LS), an inherited cancer predisposition, and a prognostic marker which predicts the response to immunotherapy. A recent trend in immunotherapy has transformed cancer treatment to provide medical alternatives that have not existed before. It is believed that MSI-high (MSI-H) CRC patients would benefit from immunotherapy due to their increased immune infiltration and higher neo-antigenic loads. MSI testing such as immunohistochemistry (IHC) and PCR MSI assay has historically been a tissue-based procedure that involves the testing of adequate tissue with a high concentration of cancer cells, in addition to the requirement for paired normal tissues. The invasive nature and specific prerequisite of such tests might hinder its application when surgery is not an option or when the tissues are insufficient. The application of next-generation sequencing, which is highly sensitive, in combination with liquid biopsy, therefore, presents an interesting possibility worth exploring. This review aimed to discuss the current body of evidence supporting the potential of liquid biopsy as a tool for MSI testing in CRC.

A single-cell atlas of the healthy breast tissues reveals clinically relevant clusters of breast epithelial cells

Single-cell RNA sequencing (scRNA-seq) is an evolving technology used to elucidate the cellular architecture of adult organs. Previous scRNA-seq on breast tissue utilized reduction mammoplasty samples, which are often histologically abnormal. We report a rapid tissue collection/processing protocol to perform scRNA-seq of breast biopsies of healthy women and identify 23 breast epithelial cell clusters. Putative cell-of-origin signatures derived from these clusters are applied to analyze transcriptomes of ~3,000 breast cancers. Gene signatures derived from mature luminal cell clusters are enriched in ~68% of breast cancers, whereas a signature from a luminal progenitor cluster is enriched in ~20% of breast cancers. Overexpression of luminal progenitor cluster-derived signatures in HER2+, but not in other subtypes, is associated with unfavorable outcome. We identify TBX3 and PDK4 as genes co-expressed with estrogen receptor (ER) in the normal breasts, and their expression analyses in >550 breast cancers enable prognostically relevant subclassification of ER+ breast cancers.

Circular RNA circ_0046264 Suppresses Osteosarcoma Progression via microRNA-940/Secreted Frizzled Related Protein 1 Axis

Circular RNAs (circRNAs) feature prominently in regulating tumor progression. The study aims to investigate the role and mechanism of circ_0046264 in osteosarcoma. In this study, dysregulated circRNAs in osteosarcoma tissues and adjacent tissues were screened out by analyzing circRNA microarray (GSE140256). The expressions of circ_0046264 in 58 osteosarcoma tissues and 4 osteosarcoma cell lines were detected by quantitative real-time polymerase chain reaction. Subsequently, the relationship of circ_0046264 expression level and clinical features were analyzed. Ethyldeoxyuridine assay and Transwell assay were employed to detect cell viability, migration and invasion. Dual-luciferase reporter assay was adopted to confirm the targeting relationships between circ_0046264 and microRNA-940 (miR-940), as well as miR-940 and secreted frizzled related protein 1 (SFRP1). SFRP1 expression was determined by western blot. Here, we demonstrated that circ_0046264 was greatly down-regulated in osteosarcoma and was inversely related to tumor size and Ki67 expression. Functional assays validated that circ_0046264 could restrain the proliferation, migration and invasion. Mechanistically, circ_0046264 could adsorb miR-940 and indirectly modulate SFRP1 expression. Furthermore, the transfection of miR-940 mimics or SFRP1 small interfering RNA could reverse the impact of circ_0046264 overexpression on the growth, migration and invasion of osteosarcoma cells. Taken together, circ_0046264 is a tumor suppressor to inhibit the osteosarcoma progression via modulating the miR-940 / SFRP1 axis.

DNA methylation analysis with methylation-sensitive high-resolution melting (MS-HRM) reveals gene panel for glioma characteristics

INTRODUCTION

Local DNA hypermethylation is a potential source of cancer biomarkers. While the evaluation of single gene methylation has limited value, their selected panel may provide better information.

AIMS

This study aimed to analyze the promoter methylation level in a 7-gene panel in brain tumors and verifies the usefulness of methylation-sensitive high-resolution melting (MS-HRM) for this purpose.

METHODS

Forty-six glioma samples and one non-neoplastic brain sample were analyzed by MS-HRM in terms of SFRP1, SFRP2, RUNX3, CBLN4, INA, MGMT, and RASSF1A promoter methylation. The results were correlated with patients' clinicopathological features.

RESULTS

DNA methylation level of all analyzed genes was significantly higher in brain tumor samples as compared to non-neoplastic brain and commercial, unmethylated DNA control. RASSF1A was the most frequently methylated gene, with statistically significant differences depending on the tumor WHO grade. Higher MGMT methylation levels were observed in females, whereas the levels of SFRP1 and INA promoter methylation significantly increased with patients' age. A positive correlation of promoter methylation levels was observed between pairs of genes, for example, CBLN4 and INA or MGMT and RASSF1A.

CONCLUSIONS

Our 7-gene panel of promoter methylation can be helpful in brain tumor diagnosis or characterization, and MS-HRM is a suitable method for its analysis.

A Novel Six-Gene Signature for Prognosis Prediction in Ovarian Cancer

Ovarian cancer (OC) is the most malignant tumor in the female reproductive tract. Although abundant molecular biomarkers have been identified, a robust and accurate gene expression signature is still essential to assist oncologists in evaluating the prognosis of OC patients. In this study, samples from 367 patients in The Cancer Genome Atlas (TCGA) database were subjected to mRNA expression profiling. Then, we used a gene set enrichment analysis (GSEA) to screen genes correlated with epithelial–mesenchymal transition (EMT) and assess their prognostic power with a Cox proportional regression model. Six genes (TGFBI, SFRP1, COL16A1, THY1, PPIB, BGN) associated with overall survival (OS) were used to construct a risk assessment model, after which the patients were divided into high-risk and low-risk groups. The six-gene signature was an independent prognostic biomarker of OS for OC patients based on the multivariate Cox regression analysis. In addition, the six-gene model was validated with samples from the Gene Expression Omnibus (GEO) database. In summary, we established a six-gene signature relevant to the prognosis of OC, which might become a therapeutic tool with clinical applications in the future.

Inactivation of Epigenetic Regulators due to Mutations in Solid Tumors

Main factors involved in carcinogenesis are associated with somatic mutations in oncogenes and tumor suppressor genes representing changes in the DNA nucleotide sequence. Epigenetic changes, such as aberrant DNA methylation, modifications of histone proteins, and chromatin remodeling, are equally important in the development of human neoplasms. From this perspective, mutations in the genes encoding key participants of epigenetic regulation are of particular interest including enzymes that methylate/demethylate DNA, enzymes that covalently attach or remove regulatory signals from histones, components of nucleosome remodeling multiprotein complexes, auxiliary proteins and cofactors of the above-mentioned molecules. This review describes both germline and somatic mutations in the key epigenetic regulators with emphasis on the latter ones in the solid human tumors, as well as considers functional consequences of these mutations on the cellular level. In addition, clinical associations of the somatic mutations in epigenetic regulators are presented, as well as DNA diagnostics of hereditary cancer syndromes due to germline mutations in the SMARC proteins and chemotherapy drugs directly affecting the altered epigenetic mechanisms for treatment of patients with solid neoplasms. The review is intended for a wide range of molecular biologists, geneticists, oncologists, and associated specialists.

EZH2 regulates sFRP4 expression without affecting the methylation of sFRP4 promoter DNA in colorectal cancer cell lines

Abnormal activation of the Wnt signaling pathway is found in 90% of colorectal cancers (CRCs). Secreted frizzled-related protein 4 (sFRP4) serves as an antagonist of the canonical Wnt signaling pathway. Epigenetic alterations, including changes in DNA methylation and histone methylation, may influence the expression of sFRP4. Polycomb group (PcG) proteins are epigenetic transcriptional repressors that selectively repress gene expression by forming polycomb repressive complexes (PRCs). Enhancer of zeste homolog 2 (EZH2), the core component of PRC2, is a histone-lysine N-methyltransferase that interacts with DNA methyltransferases. In the present study, the promoter DNA methylation status of sFRP4 in CRC cell lines was analyzed and the underlying mechanisms of action governing this modification was investigated. Firstly, the DNA methylation status of the sFRP4 promoter in CRC cell lines was assessed using methylation-specific PCR. Subsequently, the mRNA and protein levels of sFRP4 were measured using real-time qPCR and western blot analysis, respectively, to determine whether the DNA methylation status of the sFRP4 promoter is correlated with its transcriptional levels. To screen for important epigenetic modifiers that may regulate the promoter DNA methylation status of sFRP4, the expression levels of PcG proteins were examined by gene array analysis. ChIP-qPCR was performed to test whether the selected PcG proteins directly bind the promoter region of sFRP4. Finally, the downregulated PcG proteins EZH2, chromobox 7 (CBX7) and jumonji and AT-rich interaction domain containing 2 (JARID2) were identified and their association with sFRP4 expression levels and Wnt/β-catenin signaling pathway activity were investigated. The present study revealed that sFRP4 was hypermethylated in the promoter region and downregulated during the progression of the CRC cell lines from Dukes A to Dukes C. Expression levels of PcG proteins EZH2, CBX7 and JARID2 were upregulated and positively associated with the aberrantly activated Wnt signaling pathway in the CRC cell lines. EZH2, CBX7 and JARID2 were all enriched in the sFRP4 promoter region in CRC cells. EZH2 downregulation did not affect the promoter DNA methylation status of sFRP4 but increased its expression levels and decreased CRC cell proliferation. DNA methylation controls the expression of sFRP4. EZH2 regulates sFRP4 expression without affecting the DNA hypermethylation of the sFRP4 promoter and influences CRC cell proliferation and Wnt/β-catenin signaling pathway activities.

The mechanisms of sorafenib resistance in hepatocellular carcinoma: theoretical basis and therapeutic aspects

Sorafenib is a multikinase inhibitor capable of facilitating apoptosis, mitigating angiogenesis and suppressing tumor cell proliferation. In late-stage hepatocellular carcinoma (HCC), sorafenib is currently an effective first-line therapy. Unfortunately, the development of drug resistance to sorafenib is becoming increasingly common. This study aims to identify factors contributing to resistance and ways to mitigate resistance. Recent studies have shown that epigenetics, transport processes, regulated cell death, and the tumor microenvironment are involved in the development of sorafenib resistance in HCC and subsequent HCC progression. This study summarizes discoveries achieved recently in terms of the principles of sorafenib resistance and outlines approaches suitable for improving therapeutic outcomes for HCC patients.

Advanced glycation end products inhibit the osteogenic differentiation potential of adipose-derived stem cells by modulating Wnt/β-catenin signalling pathway via DNA methylation

Objectives

Advanced glycation end products (AGEs) are considered a cause of diabetic osteoporosis. Although adipose‐derived stem cells (ASCs) are widely used in the research of bone regeneration, the mechanisms of the osteogenic differentiation of ASCs from diabetic osteoporosis model remain unclear. This work aimed to investigate the influence and the molecular mechanisms of AGEs on the osteogenic potential of ASCs.

Materials and methods

Enzyme‐linked immunosorbent assay was used to measure the change of AGEs in diabetic osteoporotic and control C57BL/6 mice. ASCs were obtained from the inguinal fat of C57BL/6 mice. AGEs, 5‐aza2′‐deoxycytidine (5‐aza‐dC) and DKK‐1 were used to treat ASCs. Real‐time cell analysis and cell counting kit‐8 were used to monitor the proliferation of ASCs within and without AGEs. Real‐time PCR, Western blot and Immunofluorescence were used to analyse the genes and proteins expression of osteogenic factors, DNA methylation factors and Wnt/β‐catenin signalling pathway among the different groups.

Results

The AGEs and DNA methylation were increased in the adipose and bone tissue of the diabetic osteoporosis group. Untreated ASCs had higher cell proliferation activity than AGEs‐treatment group. The expression levels of osteogenic genes, Opn and Runx2, were lower, and mineralized nodules were less in AGEs‐treatment group. Meanwhile, DNA methylation was increased, and the Wnt signalling pathway markers, including β‐Catenin, Lef1 and P‐GSK‐3β, were inhibited. After treatment with 5‐aza‐dC, the osteogenic differentiation capacity of ASCs in the AGEs environment was restored and the Wnt signalling pathway was activated during this process.

Conclusions

Advanced glycation end products inhibit the osteogenic differentiation ability of ASCs by activating DNA methylation and inhibiting Wnt/β‐catenin pathway in vitro. Therefore, DNA methylation may be promising targets for the bone regeneration of ASCs with diabetic osteoporosis.

Plasma-Derived Extracellular Vesicles Convey Protein Signatures that Reflect Pathophysiology in Lung and Pancreatic Adenocarcinomas

Using a combination of mass-spectrometry and aptamer array-based proteomics, we characterized the protein features of circulating extracellular vesicles (EVs) in the context of lung (LUAD) and pancreatic ductal (PDAC) adenocarcinomas. We profiled EVs isolated from conditioned media of LUAD and PDAC cell lines to identify EV-associated protein cargoes released by these cancer cell types. Analysis of the resulting data identified LUAD and PDAC specific and pan-adenocarcinoma EV protein signatures. Bioinformatic analyses confirmed enrichment of proteins annotated to vesicle-associated processes and intracellular compartments, as well as representation of cancer hallmark functions and processes. Analysis of upstream regulator networks indicated significant enrichment of TP53, MYC, TGFB1 and KRAS-driven network effectors (p = 1.69 × 10^-77-2.93 × 10^-49) manifest in the adenocarcinoma sEV protein cargoes. We extended these findings by profiling the proteome of EVs isolated from lung (N = 15) and pancreatic ductal (N = 6) adenocarcinoma patient plasmas obtained at time of diagnosis, along with EVs derived from matched healthy controls (N = 21). Exploration of these proteomic data revealed abundant protein features in the plasma EVs with capacity to distinguish LUAD and PDAC cases from controls, including features yielding higher performance in the plasma EV isolates relative to unfractionated plasmas.