Epigenetic down-regulation of SOX2 is an independent poor prognostic factor for hypopharyngeal cancers

Diagnostic value of plasma RNF180 gene methylation for gastric cancer: A systematic review and meta-analysis

Objective

A systematic evaluation of the diagnostic value of Ring finger protein 180 (RNF180) gene methylation as a novel tumor marker for gastric cancer (GC) is required to improve the early diagnosis of gastric cancer patients.

Methods

Computer searches of PubMed, Web of Science, Embase, The Cochrane Library, CNKI, CBM, WanFang Data, National Research Register, Cclinical Controlled Trials, Opengrey and VIP databases were conducted from the database's inception to September 1, 2022. Two researchers independently screened the literature, extracted information, and assessed the risk of bias in studies that were included. The meta-analysis was carried out using RevMan 5.3 and Stata 16.0 software.

Results

A total of 9 studies with a total of 1531 subjects were included. A random-effects meta-analysis revealed that the combined sensitivity (SEN), specificity (SPE), positive likelihood ratio (PLR), negative likelihood ratio (NLR), and diagnostic odds ratio (DOR) of plasma RNF180 gene methylation for the diagnosis of GC were: 0.54 [95% CI (0.45, 0.62)], 0.80 [95% CI (0.72, 0.87)], 2.73 [95% CI (2.09, 3.57)], 0.58 [95% CI (0.51, 0.65)], 4.74 [95% CI (3.59, 6.62)], respectively.

Conclusion

The detection of RNF180 gene methylation in plasma has a high diagnostic value for GC and is expected to be a potential biomarker for the diagnosis of gastric cancer, according to current evidence.

Systematic review registration

https://www.crd.york.ac.uk/PROSPERO/display_record.php?RecordID=370903, identifier CRD42022370903.

Understanding the function and regulation of Sox2 for its therapeutic potential in breast cancer

Sox family of transcriptional factors play essential functions in development and are implicated in multiple clinical disorders, including cancer. Sox2 being their most prominent member and performing a critical role in reprogramming differentiated adult cells to an embryonic phenotype is frequently upregulated in multiple cancers. High Sox2 levels are detected in breast tumor tissues and correlate with a worse prognosis. In addition, Sox2 expression is connected with resistance to conventional anticancer therapy. Together, it can be said that inhibiting Sox2 expression can reduce the malignant features associated with breast cancer, including invasion, migration, proliferation, stemness, and chemoresistance. This review highlights the critical roles played by the Sox gene family members in initiating or suppressing breast tumor development, while primarily focusing on Sox2 and its role in breast tumor initiation, maintenance, and progression, elucidates the probable mechanisms that control its activity, and puts forward potential therapeutic strategies to inhibit its expression.

Air pollution and DNA methylation in adults: A systematic review and meta-analysis of observational studies

This systematic review and meta-analysis aimed to investigate the association between air pollution and DNA methylation in adults from published observational studies. PubMed, Web of Science and Embase databases were systematically searched for available studies on the association between air pollution and DNA methylation published up to March 9, 2021. Three DNA methylation approaches were considered: global methylation, candidate-gene, and epigenome-wide association studies (EWAS). Meta-analysis was used to summarize the combined estimates for the association between air pollutants and global DNA methylation levels. Heterogeneity was assessed with the Cochran Q test and quantified with the I² statistic. In total, 38 articles were included in this study: 16 using global methylation, 18 using candidate genes, and 11 using EWAS, with 7 studies using more than one approach. Meta-analysis revealed an imprecise but inverse association between exposure to PM_2.5 and global DNA methylation (for each 10-μg/m³ PM_2.5, combined estimate: 0.39; 95% confidence interval: 0.97 - 0.19). The candidate-gene results were consistent for the ERCC3 and SOX2 genes, suggesting hypermethylation in ERCC3 associated with benzene and that in SOX2 associated with PM_2.5 exposure. EWAS identified 201 CpG sites and 148 differentially methylated regions that showed differential methylation associated with air pollution. Among the 307 genes investigated in 11 EWAS, a locus in nucleoredoxin gene was found to be positively associated with PM_2.5 in two studies. Current meta-analysis indicates that PM_2.5 is imprecisely and inversely associated with DNA methylation. The candidate-gene results consistently suggest hypermethylation in ERCC3 associated with benzene exposure and that in SOX2 associated with PM_2.5 exposure. The Kyoto Encyclopedia of Genes and Genomes (KEGG) network analyses revealed that these genes were associated with African trypanosomiasis, Malaria, Antifolate resistance, Graft-versus-host disease, and so on. More evidence is needed to clarify the association between air pollution and DNA methylation.

RNA methyltransferase NSUN2 promotes hypopharyngeal squamous cell carcinoma proliferation and migration by enhancing TEAD1 expression in an m5C-dependent manner

RNA methyltransferase NSUN2 is involved in cell proliferation and invasion in a variety of tumors. However, the expression, function, and mechanism of NSUN2 in hypopharyngeal squamous cell carcinoma (HPSCC) remains unknown. We used a bioinformatics database, polymerase chain reaction, cell culture and transfection, immunohistochemistry, cell proliferation assay, wound healing experiments, transwell assays, western blotting, RNA-seq detection, dual-luciferase reporter assay, in vivo experiments, and a dot blot assay to evaluate the role of NSUN2 in HPSCC. NSUN2 mRNA and protein were highly expressed in HPSCC; NSUN2 knockdown in vitro and in vivo decreased cell proliferation and invasion. Studies have shown that TEAD1, a transcription factor, may act downstream of NSUN2 in HPSCC. NSUN2 was found to promote the proliferation and invasion of HPSCC by upregulating TEAD1 in an 5-methylcytosine-dependent manner, thereby representing an oncogene and potential new target for treating HPSCC.

Identification of High-Frequency Methylation Sites in RNF180 Promoter Region Affecting Expression and Their Relationship with Prognosis of Gastric Cancer

Background

Ring finger protein 180 (RNF180) is a tumor suppressor gene regulated by promoter methylation. We previously demonstrated that the RNF180 promoter methylation could be a risk factor for gastric cancer (GC); and eight high-frequency hypermethylated CpG sites were associated with GC. However, it is not clear whether these key sites can affect gene expression and involve in prognosis. The aim of this study was to investigate the effects of above CpG sites on the gene expression and prognosis of GC.

Patients and Methods

A total of 164 GC tissues were enrolled and followed up. Tissue samples were used for DNA and RNA isolation. Methylation status of RNF180 was detected using bisulfite sequencing PCR (BSP). Expression levels of RNF180 were detected using quantitative real-time reverse transcription-polymerase chain reaction (qRT-PCR). JASPAR and PROMO databases were used to predict the transcription factors (TFs) binding to the CpG site.

Results

The methylation in RNF180 promoter region increased and mRNA expression decreased in GC tissue. Correlation analysis revealed that the average methylation rate (AMR) and four CpG sites methylation rate were negatively related to RNF180 expression, including M3(−165)(Chr5:64165942), M5(−148)(Chr5:64,165,959), M7(−133)(Chr5:64,165,974) and M8(−130)(Chr5:64,165,977). Furthermore, the methylation rate of M5(−148)(Chr5:64,165,959) and M27(−26)(Chr5:64,166,081) above 0.3 indicated poor prognosis (P_M5 = 0.008, P_M27 = 0.003, HR_M5(−148) = 2.000 (1.201,3.332), HR_M27(−26)=2.389 (1.336,4.271)), which could be independent factors of prognosis.

Conclusion

By focusing on the methylation sites in the RNF180 promoter region, we identified two high-frequency methylation sites, M5(−148)(Chr5:64,165,959) and M27(−26)(Chr5:64,166,081), which could affect gene expression and predict the prognosis of GC. In the future, the possible molecular mechanism involved needs to be further studied.

Blood-Based SOX2-Promoter Methylation in Relation to Exercise and PM2.5 Exposure among Taiwanese Adults

Increased ventilation during exercise in polluted areas could trigger airway inflammation. We evaluated blood DNA methylation of the SOX2-promoter region in relation to exercise and PM_2.5 in Taiwanese adults. Data of 948 participants aged 30–70 years were retrieved from the Taiwan Biobank Database (2008–2015) and the Air Quality Monitoring Database (2006–2011). PM_2.5 was positively associated with SOX2-promoter methylation (β = 0.000216; p < 0.0001). The interaction between PM_2.5 and exercise on SOX2-promoter methylation was significant (p = 0.0146). After stratification by exercise habits, PM_2.5 was positively associated with SOX2 methylation in only individuals who did regular exercise (β = 0.0003490; p < 0.0001). After stratification by exercise habits and residential areas, SOX2-promoter methylation levels in those who lived in the southern area were higher for both the regular exercise (β = 0.00272; p = 0.0172) and no regular exercise groups (β = 0.002610 and p = 0.0162). SOX2-promoter methylation levels in those who lived in the northern area and did regular exercise were lower; β = -0.00314 (p = 0.0036). In conclusion, PM_2.5 was positively associated with SOX2-promoter methylation in participants who did regular exercise. Living in the southern area was positively associated with SOX2-promoter methylation regardless of exercise habits.

Leading edge or tumor core: Intratumor cancer stem cell niches in oral cavity squamous cell carcinoma and their association with stem cell function

OBJECTIVES

To describe differences in cancer stem cell (CSC) presence and behavior associated with their intratumor compartment of origin using a patient-derived xenograft (PDX) model of oral cavity squamous cell carcinoma (OCSCC).

MATERIALS AND METHODS

Four HPV-negative OCSCC PDX cases were selected (CUHN004, CUHN013, CUHN096, CUHN111) and the percentage of CSCs (ALDH⁺CD44^high) was measured in the tumor Leading Edge (LE) and Core compartments of each PDX tumor case via fluorescence activated cell sorting (FACS). The fraction of cells in the proliferative phase was measured by Ki-67 labelling index of paraffin embedded tissue. The proliferation and invasion of LE versus Core CSCs were compared using sphere and Matrigel invasion assays, respectively.

RESULTS

Both CUHN111 and CUHN004 demonstrate CSC enrichment in their LE compartments while CUHN013 and CUHN096 show no intratumor difference. Cases with LE CSC enrichment demonstrate greater Ki-67 labelling at the LE. CSC proliferative potential, assessed by sphere formation, reveals greater sphere formation in CUHN111 LE CSCs, but no difference between CUHN013 LE and Core CSCs. CUHN111 CSCs do not demonstrate an intratumor difference in invasiveness while CUHN013 LE CSCs are more invasive than Core CSCs.

CONCLUSION

A discrete intratumor CSC niche is present in a subset of OCSCC PDX tumors. The CSC functional phenotype with regard to proliferation and invasion is associated with the intratumor compartment of origin of the CSC: LE or Core. These individual functional characteristics appear to be modulated independently of one another and independently of the presence of an intratumor CSC niche.

SOX2 promoter hypermethylation in non-smoking Taiwanese adults residing in air pollution areas

BACKGROUND

Both SOX2 promoter methylation and air pollution have been associated with lung cancer risk. However, little has been done to assess SOX2 promoter methylation in individuals living in air pollution areas. The aim of this study was to investigate SOX2 promoter methylation in non-smoking Taiwanese adults living in areas with different levels of air pollution especially particulate matter with diameter < 2.5 μm (PM2.5).

METHODS

A total of 1142 individuals aged 30-70 years were recruited. Data on SOX2 methylation, residence, age, and exposure to second-hand smoke (SHS) among others were extracted from the Taiwan Biobank dataset (2008-2015). After excluding former and current smokers, alongside those with incomplete information, a total of 461 non-smokers comprising 176 men and 285 women were included in the study. Participants' residences were grouped under northern and central/southern areas because air pollution (PM2.5) is lower in northern compared to central and southern areas.

RESULTS

The methylation levels in men (0.16310 ± 0.01230) and women (0.15740 ± 0.01240) were significantly different (P < .0001). In both sexes, the SOX2 promoter region was shown to be significantly hypermethylated in central and southern areas compared with the northern areas. The regression coefficient (β) was 0.00331 (P = 0.0257) in men and 0.00514 (P < .0001) in women.

CONCLUSION

SOX2 was significantly hypermethylated in both men and women residing in central and southern areas. The consistency in the results for both sexes shows that SOX2 promoter methylation could serve as a potential biomarker for industrial air pollution exposure. Moreover, it might reflect predisposition to cancer. Hence, healthy non-smokers at precancerous stages who have not been clinically diagnosed could be identified.