The Roles of microRNA miR-185 in Digestive Tract Cancers.

Digestive tract cancers represent a serious public health issue. In recent years, evidence has accumulated that microRNA miR-185 is implicated in the pathogenesis of this group of highly malignant tumors. Its expression variations correlate with clinical features, such as tumor size, lymph node metastasis, tumor node metastatic stage, survival, recurrence and response to adjuvant therapy, and have diagnostic and prognostic potential. In this review, we compile, evaluate and discuss the current knowledge about the roles of miR-185 in digestive tract cancers. Interestingly, miR-185 is apparently involved in regulating both tumor suppressive and oncogenic processes. We look at downstream effects as well as upstream regulation. In addition, we discuss the utility of miR-185 for diagnosis and its potential concerning novel therapeutic approaches.

The effect of benzo[alpha]pyrene on DNA methylation and telomerase activity in human normal and cancer cells.

Benzo[a]pyrene (BaP) exposure has been associated with an increased risk of carcinogenesis. We investigated the effects of BaP on cell viability, the promoter methylation of 11 tumor-associated genes, the global DNA methylation, and telomerase enzyme activity in 5 human cancer cell lines (HCT116, PC3, MDA-MB-231, A549, and HepG2) and normal human peripheral blood mononuclear cells (PBMCs) and adipose-derived mesenchymal stem cells (AD-MSCs). BaP inhibited the proliferation of cells in a dose-dependent manner, as measured by MTT assay. Human normal cells were more sensitive to BaP cytotoxicity than cancer cells. After treatment with the minimally toxic concentration of BaP (5 µM for 72 h), 3 differentially methylated genes (genes with different promoter methylation status) were identified between BaP-treated and untreated control cells, as verified by MSP analysis. BaP induced hypomethylation of COX-2 and MSH2 in normal PBMCs and hypermethylation of APC in HCT116 CRC cells. BaP also non-significantly decreased global methylation levels in 3 cancer cell lines (HCT16, PC3, and A549), as measured by ELISA assay. BaP also reduced telomerase enzyme activity in human AD-MSC cells in a dose-dependent manner. To our knowledge, this is the first report of BaP-effects on telomerase activity and DNA methylation in human normal and cancer cells.

Bilirubin and Epigenetic Modifications in Metabolic and Immunometabolic Disorders.

Bilirubin is the main waste product of heme catabolism. At high concentrations, bilirubin may cause toxicity, especially in the brain, kidney, and erythrocytes. Membrane and mitochondrial dysfunction, oxidative stress, apoptosis, necrosis, endoplasmic reticulum stress, excitotoxicity, inflammation, and epigenetic modifications are the main mechanisms of toxicity triggered by bilirubin in susceptible organs. Many studies have shown that there is an interaction between bilirubin and epigenetic modifications in metabolic and immune diseases. In this review, we first outline the toxicity mediated by bilirubin and then summarize the current knowledge linking bilirubin and epigenetic modifications in metabolic and immunometabolic disorders.

Effects of Pistacia atlantica on Oxidative Stress Markers and Antioxidant Enzymes Expression in Diabetic Rats.

INTRODUCTION: Diabetes mellitus (DM) affects many patients all over the world. It involves different parts of the body, such as brain, eyes, kidneys, vessels, and so on. The lack of balance between free radicals and antioxidants is a possible mechanism involved in the pathogenesis of diabetes. Antioxidant treatment, especially natural forms, can be a beneficial solution. Therefore, we evaluated the effects of Pistacia atlantica oleoresin (PAO) on oxidative stress markers and antioxidant enzymes expression in diabetic rats. METHOD: Fifty adult male Wistar rats were allotted randomly into five groups as follow: control group, diabetic control group, glibenclamide control group, diabetic glibenclamide group, diabetic treated group with 200 mg/kg PAO. Then PAO was prepared and analyzed by gas chromatography/mass spectroscopy (GC/MS). LD50 was also estimated for essential oil. Oxidative stress markers and antioxidant enzyme including malondialdehyde (MDA), glutathione (GSH), glutathione peroxidase (GPx), catalase (CAT), and superoxide dismutase (SOD) were also measured. The expression of GPx, CAT, and SOD genes was investigated using real-time polymerase chain reaction (PCR). RESULTS: The main constituents of essential oil gum were beta-pinene (29.38%), followed by alpha-pinene (18.15%), myrcene (7.36%), trans-pinocarveol (7.15%), and camphene (4.12%). Diabetes induced an increased level of MDA (69.92 ± 3.92 vs. 43.76 ± 3.73) and decreased levels of GSH (2.57 ± 0.40 vs. 7.05 ± 1.59), GPx (11.66 ± 2.2 vs. 16.38 ± 2.1), CAT (12.17 ± 3.38 vs. 18.7 ± 2.66), and SOD (0.78 ± 0.67 vs. 2.41 ± 0.46). In contrast, PAO treatment significantly decreased MDA (54.59 ± 12.54 vs. 69.92 ± 3.92) and increased GSH (4.5 ± 0.89 vs. 2.57 ± 0.40), GPx (25.86 ± 5.37 vs. 11.66 ± 2.2), CAT (22.69 ± 0.36 vs. 12.17 ± 3.38), and SOD (3.65 ± 1.08 vs. 0.78 ± 0.67) (p < 0.05). Moreover, our results indicated that both GPx and CAT mRNA levels significantly increased approximately 4.46 and 6.23 times in rats fed with 200 mg/kg of PAO, more than that of the healthy control group, respectively (p < 0.01 and p < 0.001, respectively). Also, the average expression level of SOD was also significantly 1.57 higher in rats fed with 200 mg/kg of PAO in comparison to the diabetic control group (p < 0.05). CONCLUSION: The results indicated that PAO could be propose as an agent that protects the body against diseases that are associated with oxidative stress.

The impact of polyunsaturated fatty acids on DNA methylation and expression of DNMTs in human colorectal cancer cells.

Growing evidence suggests a role of polyunsaturated fatty acids (PUFA) in the prevention of various types of malignancy, including colorectal cancer (CRC). No published studies have yet examined the direct effect of PUFA treatment on DNA methylation in CRC cells. In this study, 5 human CRC cells were treated with 100 µM DHA, EPA, and LA for 6 days and changes in their global- and gene-specific DNA methylation status as well as expression of DNA methyl transferases (DNMT) were investigated. Cell-type specific differences in DNA methylation and expression of DNMTs were observed in PUFA-treated cells. DHA and EPA treatment induced global hypermethylation in HT29/219 and HCT116 cells, but reduced methylation in Caco2 cells (p < 0.05). Among 10 tumor related genes tested in 5 CRC cell lines, DHA and EPA induced promoter demethylation of Cox2 in HT29/219, p14 and PPARγ in HCT116, and ECAD in SW742 cells. Cell-type specific differences in expression of DNMT1, DNMT3a, and 3b genes were also observed between PUFA-treated and control cells (p < 0.05). Overall, treatment of PUFAs coordinately induced the expression of DNMTs in HT29/219, but suppressed in other 4 cell lines investigated in this study.

Association of DNA methyltransferases expression with global and gene-specific DNA methylation in colorectal cancer cells.

There are conflicting reports regarding the association between DNA methyltransferases (DNMTs) expression and global or gene-specific DNA methylation in colorectal cancer (CRC) cells. To correlate DNMTs expression with DNA methylation, we quantified DNMT1, DNMT3A and DNMT3B mRNA levels in five CRC cell lines (HCT116, LS180, HT29/219, Caco2 and SW742) by real-time reverse-transcriptase polymerase chain reaction (PCR) assay. In addition, we examined the global 5-methyl cytosine levels and the methylation patterns of 12 CpG islands in these CRC cells by enzyme-linked immunosorbent assay and methylation-specific PCR methods, respectively. The average expression levels of three DNMTs in HCT116, Caco2, HT29/219 and SW742, relative to the expression level in LS180 (taken to be 1), were 90.1, 31.6, 2.66 and 1.86. Our data indicated that overall about 1.45%, 1.03%, 0.98%, 0.86% and 0.85% of the cytosines were methylated in the genome of HCT116, Caco2, HT29/219, SW742 and LS180 cells, respectively. The 5-mC percentages were positively correlated with the relative cellular DNMTs expression in five CRC cell lines as verified by Pearson correlation test. However, we found no positive correlation between mRNA expression of DNMTs and gene promoter hypermethylation in these cells. Our results suggest that cellular DNMT expression is positively correlated with global DNA methylation level but not with regional DNA hypermethylation at each locus.

MGMT-B gene promoter hypermethylation in patients with inflammatory bowel disease - a novel finding.

Inflammatory bowel disease (IBD) is a disease strongly associated with colorectal cancer (CRC) as a well-known precancerous condition. Alterations in DNA methylation and mutation in K-ras are believed to play an early etiopathogenic role in CRC and may also an initiating event through deregulation of molecular signaling. Epigenetic silencing of APC and SFRP2 in the WNT signaling pathway may also be involved in IBD-CRC. The role of aberrant DNA methylation in precancerous state of colorectal cancer (CRC) is under intensive investigation worldwide. The aim of this study was to investigate the status of promoter methylation of MGMT-B, APC1A and SFRP2 genes, in inflamed and normal colon tissues of patients with IBD compared with control normal tissues. A total of 52 IBD tissues as well as corresponding normal tissues and 30 samples from healthy participants were obtained. We determined promoter methylation status of MGMT-B, SFRP2 and APC1A genes by chemical treatment with sodium bisulfite and subsequent MSP. The most frequently methylated locus was MGMT-B (71%; 34 of 48), followed by SFRP2 (66.6 %; 32 of 48), and APC1A (43.7%; 21 of 48). Our study demonstrated for the first time that hypermethylation of the MGMT-B and the SFRP2 gene promoter regions might be involved in IBD development. Methylation of MGMT-B and SFRP2 in IBD patients may provide a method for early detection of IBD-associated neoplasia.

Promoter Methylation Status of Two Novel Human Genes, UBE2Q1 and UBE2Q2, in Colorectal Cancer: a New Finding in Iranian Patients.

BACKGROUND: The ubiquitin-proteasome system (UPS) degrades a variety of proteins which attach to specific signals. The ubiquitination pathway facilitates degradation of damaged proteins and regulates growth and stress responses. This pathway is altered in various cancers, including acute lymphoblastic leukemia, head and neck squamous cell carcinoma and breast cancer. Recently it has been reported that expression of newly characterized human genes, UBE2Q1 and UBE2Q2, putative members of ubiquitin-conjugating enzyme family (E2), has been also changed in colorectal cancer. Epigenetics is one of the fastest-growing areas of science and nowadays has become a central issue in biological studies of diseases. According to the lack of information about the role of epigenetic changes on gene expression profiling of UBE2Q1 and UBE2Q2, and the presence of CpG islands in the promoter of these two human genes, we decided to evaluate the promoter methylation status of these genes as a first step. MATERIALS AND METHODS: The promoter methylation status of UBE2Q1 and UBE2Q2 was studied by methylation-specific PCR (MSP) in tumor samples of 60 colorectal cancer patients compared to adjacent normal tissues and 20 non-malignant controls. The frequency of the methylation for each gene was analyzed by chi-square method. RESULTS: MSP results revealed that UBE2Q2 gene promoter were more unmethylated, while a higher level of methylated allele was observed for UBE2Q1 in tumor tissues compared to the adjacent normal tissues and the non malignant controls. CONCLUSIONS: UBE2Q1 and UBE2Q2 genes show different methylation profiles in CRC cases.