Genome-wide DNA methylation profiling in tongue squamous cell carcinoma.

OBJECTIVES: To provide a comprehensive characterization of DNA methylome of oral tongue squamous cell carcinoma (OTSCC) and identify novel tumor-specific DNA methylation markers for early detection using saliva. MATERIAL AND METHODS: Genome-wide DNA methylation analysis including six OTSCC matched adjacent non-tumoral tissue and saliva was performed using Infinium MethylationEPIC array. Differentially methylated levels of selected genes in our OTSCC cohort were further validated using OTSCC methylation data from The Cancer Genome Atlas database (TCGA). The methylation levels of a set of tumor-specific hypermethylated genes associated with a downregulated expression were evaluated in saliva. Receiver operating characteristic (ROC) curves were performed to assess the diagnostic value of DNA methylation markers. RESULTS: A total of 25,890 CpGs (20,505 hypomethylated and 5385 hypermethylated) were differentially methylated (DMCpGs) between OTSCC and adjacent non-tumoral tissue. Hypermethylation of 11 tumor-specific genes was validated in OTSCC TCGA cohort. Of these 11 genes, A2BP1, ANK1, ALDH1A2, GFRA1, TTYH1, and PDE4B were also hypermethylated in saliva. These six salivary methylated genes showed high diagnostic accuracy (≥0.800) for discriminating patients from controls. CONCLUSIONS: This is the first largest genome-wide DNA methylation study on OTSCC that identifies a group of novel tumor-specific DNA methylation markers with diagnostic potential in saliva.

Adipose tissue inflammation and VDR expression and methylation in colorectal cancer.

Background: Lack of vitamin D (VD) has been associated with colorectal cancer (CRC). VD has anti-inflammatory effects and regulates several cellular pathways by means of its receptor, including epigenetic modifications. Adipose tissue dysfunction has been related to low-grade inflammation, which is related to diseases like cancer. The aim of this study was to explore the relationship between serum 25-hydroxyvitamin D (25(OH)D), adipose tissue gene expression of VD receptor (VDR), pro-inflammatory markers, and the epigenetic factor DNA methyltransferase 3a (DNMT3A) as well as VDR promoter methylation in CRC. Methods: Blood and visceral adipose tissue from 57 CRC and 50 healthy control subjects were collected. CRC subjects had lower serum 25(OH)D levels and higher VDR gene expression, and these were negatively correlated in the CRC group. Results: Adipose tissue NFκB1, IL6, and IL1B gene expression were higher in the CRC subjects than in the control subjects. 25(OH)D correlated negatively with NFκB1 and CRP. In turn, CRP correlated positively with NFκB1, IL6, IL1B, and VDR gene expression as well as NFκB1 that correlated positively with IL6 and IL1B. DNMT3A mRNA was negatively correlated with serum 25(OH)D and positively correlated with VDR DNA methylation. VDR DNA methylation at position 4 had lower levels in the CRC group. Global NFκB1 methylation at dinucleotide 3 was lower in the CRC group. Conclusion: Our results suggest that adipose tissue may be a key factor in CRC development. The low 25(OH)D levels and high adipose tissue VDR expression in CRC may, at least in part, mediate this relationship by modifying adipose tissue DNA methylation and promoting inflammation.

Notch1 Pathway Activation Results from the Epigenetic Abrogation of Notch-Related MicroRNAs in Mycosis Fungoides.

Notch is a family of transmembrane receptors that participate in the regulation of cell differentiation, proliferation, and stemness. Notch pathway activation has also been found associated with different human cancers including primary cutaneous T-cell lymphomas (CTCL). The elucidation of the mechanisms driving Notch activation in these particular diseases has remained elusive. Here we studied the possibility that DNA methylation at Notch pathway gene promoters and/or deregulation of Notch-associated microRNAs contribute to activate Notch in mycosis fungoides (MF). By genome-wide DNA methylation analysis, we failed to detect any consistent methylation at the Notch1, the Notch-ligand Jagged1, or the Notch-target Hes1 gene promoters, but found a significant methylation of the Notch-related microRNAs, in particular miR-200c and miR-124. Downregulation of miR-200c is associated with overexpression of Jagged1, concomitant to Notch1 activation. CTCL cell lines were infected with lentiviral vector encoding for miR-200c and ectopic expression of miR-200c in CTCL lines resulted in Jagged1 protein downregulation associated with a reduction in the levels of active Notch1. Our study deciphers an epigenetic mechanism regulating the Notch pathway in (MF) that might contribute to the future design of more specific therapeutic strategies.

Preproghrelin expression is a key target for insulin action on adipogenesis.

This study aimed to investigate the role of preproghrelin-derived peptides in adipogenesis. Immunocytochemical analysis of 3T3-L1 adipocyte cells showed stronger preproghrelin expression compared with that observed in 3T3-L1 preadipocyte cells. Insulin promoted this expression throughout adipogenesis identifying mTORC1 as a critical downstream substrate for this profile. The role of preproghrelin-derived peptides on the differentiation process was supported by preproghrelin knockdown experiments, which revealed its contribution to adipogenesis. Neutralization of endogenous O-acyl ghrelin (acylated ghrelin), unacylated ghrelin, and obestatin by specific antibodies supported their adipogenic potential. Furthermore, a parallel increase in the expression of ghrelin-associated enzymatic machinery, prohormone convertase 1/3 (PC1/3) and membrane-bound O-acyltransferase 4 (MBOAT4), was dependent on the expression of preproghrelin in the course of insulin-induced adipogenesis. The coexpression of preproghrelin system and their receptors, GHSR1a and GPR39, during adipogenesis supports an autocrine/paracrine role for these peptides. Preproghrelin, PC1/3, and MBOAT4 exhibited dissimilar expression depending on the white fat depot, revealing their regulation in a positive energy balance situation in mice. The results underscore a key role for preproghrelin-derived peptides on adipogenesis through an autocrine/paracrine mechanism.

Obestatin as a regulator of adipocyte metabolism and adipogenesis.

The role of obestatin, a 23-amino-acid peptide encoded by the ghrelin gene, on the control of the metabolism of pre-adipocyte and adipocytes as well as on adipogenesis was determined. For in vitro assays, pre-adipocyte and adipocyte 3T3-L1 cells were used to assess the obestatin effect on cell metabolism and adipogenesis based on the regulation of the key enzymatic nodes, Akt and AMPK and their downstream targets. For in vivo assays, white adipose tissue (WAT) was obtained from male rats under continuous subcutaneous infusion of obestatin. Obestatin activated Akt and its downstream targets, GSK3α/ß, mTOR and S6K1, in 3T3-L1 adipocyte cells. Simultaneously, obestatin inactivated AMPK in this cell model. In keeping with this, ACC phosphorylation was also decreased. This fact was confirmed in vivo in white adipose tissue (omental, subcutaneous and gonadal) obtained from male rats under continuous sc infusion of obestatin (24 and 72 hrs). The relevance of obestatin as regulator of adipocyte metabolism was supported by AS160 phosphorylation, GLUT4 translocation and augment of glucose uptake in 3T3-L1 adipocyte cells. In contrast, obestatin failed to modify translocation of fatty acid transporters, FATP1, FATP4 and FAT/CD36, to plasma membrane. Obestatin treatment in combination with IBMX and DEX showed to regulate the expression of C/EBPα, C/EBPß, C/EBPδ and PPARγ promoting adipogenesis. Remarkable, preproghrelin expression, and thus obestatin expression, increased during adipogenesis being sustained throughout terminal differentiation. Neutralization of endogenous obestatin secreted by 3T3-L1 cells by anti-obestatin antibody decreased adipocyte differentiation. Furthermore, knockdown experiments by preproghrelin siRNA supported that obestatin contributes to adipogenesis. In summary, obestatin promotes adipogenesis in an autocrine/paracrine manner, being a regulator of adipocyte metabolism. These data point to a putative role in the pathogenesis of metabolic syndrome.

Inflammatory state and stress condition in weight-lowering Lys109Arg LEPR gene polymorphism carriers.

BACKGROUND AND AIMS: Carrying variants on the leptin receptor gene (LEPR) may have an impact on inflammatory and stress markers. Thus, the aim of the study was to analyze the role of the Lys109Arg LEPR gene polymorphism on inflammatory (leptin and IL-6) and stress (cortisol) markers in obese subjects who followed a hypocaloric diet designed to lose weight. METHODS: One hundred and seventy (80 females/90 males) Caucasian subjects (body mass index: 30.8 +/- 2.4 kg/m(2)), were genotyped for the Lys109Arg polymorphism by a PCR/RFLP procedure. Anthropometric measurements were assessed and blood samples were drawn in all the volunteers before and after an 8-week energy-restricted diet (-30% E). Plasma levels of leptin as well as interleukin-6 (IL-6) as proinflammatory markers and circulating cortisol concentrations as a stress hormone were measured. RESULTS: Weight loss (-6.1 +/- 2.7%; p <0.001) induced significant changes in anthropometric and biochemical determinations. The AA genotype group showed a higher fat mass loss as well as greater total cholesterol decrease compared with the minor allele carriers. Moreover, the G allele carriers were associated with a higher basal risk of inflammation (OR = 2.5; p = 0.042) and stress (OR = 3.3; p = 0.011), which were reduced after weight lowering (p >0.05). CONCLUSIONS: The Arg allele carriers of the Lys109Arg LEPR gene polymorphism were associated with an increased proinflammatory state and stress condition at baseline. These obesity-related markers were importantly decreased after following a hypocaloric diet.