One of the most prevalent and lethal forms of gynecological cancer is ovarian cancer (OC), which is often diagnosed in its latter, deadly stages. The OC's high mortality and heterogeneity impede early identification and primary prevention. Thus, numerous studies have looked for biomarkers in OC tissue and blood samples to help early diagnosis and decrease the mortality rate using microRNAs (miRNAs). The miRNAs are short, noncoding RNAs (ncRNAs) that are typically approximately 22 nucleotides in length and act as oncogenic or tumor suppressors via degrading or impeding target mRNA translation. By regulating cellular activities and signaling pathways, miRNAs promote carcinogenesis and the invasiveness of OC cells. In this review, we explore the function of miRNAs in the pathophysiology of OC, their use as biomarkers, future implications, and the direction of future research. The review also underlines the involvement of miRNAs in the most significant pathways affecting the pathogenesis of OC and their relevance to treatment resistance. 

The role of miRNAs in ovarian cancer pathogenesis and therapeutic resistance - A focus on signaling pathways interplay.

Methylenetetrahydrofolate reductase (MTHFR) is a pivotal enzyme in the one-carbon metabolism, a metabolic pathway required for DNA synthesis and methylation reactions. MTHFR hypermethylation, resulting in reduced gene expression, can contribute to several human disorders, but little is still known about the factors that regulate MTHFR methylation levels. We performed the present study to investigate if common polymorphisms in one-carbon metabolism genes contribute to MTHFR methylation levels. MTHFR methylation was assessed in peripheral blood DNA samples from 206 healthy subjects with methylation-sensitive high-resolution melting (MS-HRM); genotyping was performed for MTHFR 677C>T (rs1801133) and 1298A>C (rs1801131), MTRR 66A>G (rs1801394), MTR 2756A>G (rs1805087), SLC19A1 (RFC1) 80G>A (rs1051266), TYMS 28-bp tandem repeats (rs34743033) and 1494 6-bp ins/del (rs34489327), DNMT3A -448A>G (rs1550117), and DNMT3B -149C>T (rs2424913) polymorphisms. We observed a statistically significant effect of the DNMT3B -149C>T polymorphism on mean MTHFR methylation levels, and particularly CT and TT carriers showed increased methylation levels than CC carriers. The present study revealed an association between a functional polymorphism of DNMT3B and MTHFR methylation levels that could be of relevance in those disorders, such as inborn defects, metabolic disorders and cancer, that have been linked to impaired DNA methylation.

https://www.mdpi.com/1422-0067/20/15/3754/pdf

Association of Polymorphisms in Genes Involved in One-Carbon Metabolism with MTHFR Methylation Levels

DNA methylation is an epigenetic mechanism for regulating the transcription of many genes and has been linked to the development of various diseases. A promising gene to investigate is methylenetetrahydrofolate reductase (MTHFR), since the enzyme methylenetetrahydrofolate reductase (MTHFR) promotes methyl radical synthesis in the homocysteine cycle and can provide methyl groups for DNA methylation. In addition, several studies have correlated gene polymorphisms of this enzyme with a greater risk of diabetes, but little is known regarding the relationship between epigenetic changes in this gene and diabetes and its complications. The aim of this study was to investigate the relationship between methylation profile in the MTHFR gene promoter and biochemical, inflammatory and oxidative stress markers in individuals with type 2 diabetes (T2DM) who have been diagnosed for 5–10 years with or without diabetic retinopathy (DR) and nephropathy (DN). Specific PCR for methylation (MSP) was used to analyze MTHFR methylation profile in leucocytes DNA. Biochemical markers (glycemia, glycated hemoglobin, total cholesterol, LDL, HDL, triglycerides, serum creatinine), inflammatory markers (C-reactive protein and alpha-1 acid glycoprotein) and oxidative stress (total antioxidant and malonaldehyde) were determined in peripheric blood samples and microalbuminuria in 24 h urine samples. The X2 and Mann–Whitney statistical tests were performed and p < 0.05 were considered significant. The hypermethylated profile was most frequently observed in individuals with retinopathy (p < 0.01) and was associated with higher total cholesterol and LDL levels (p = 0.0046, 0.0267, respectively). Individuals with DN and hypermethylated profiles had higher levels of alpha-1 acid glycoprotein (p = 0.0080) and total antioxidant capacity (p = 0.0169) compared to subjects without complications. Hypermethylation in the promoter of the MTHFR gene is associated with the occurrence of DR and with biochemical, inflammatory and oxidative stress parameters in the context of chronic complications

/pdf/hypermethylation-in-the-promoter-of-the-mthfr-gene-is-2wu8j2ajpq.pdf

Hypermethylation in the promoter of the MTHFR gene is associated with diabetic complications and biochemical indicators.

Despite that advanced maternal age at conception represents the major risk factor for the birth of a child with Down syndrome (DS), most of DS babies are born from women aging less than 35 years. Studies performed in peripheral lymphocytes of those women revealed several markers of global genome instability, including an increased frequency of micronuclei, shorter telomeres and impaired global DNA methylation. Furthermore, young mothers of DS individuals (MDS) are at increased risk to develop dementia later in life, suggesting that they might be "biologically older" than mothers of euploid babies of similar age. Mutations in folate pathway genes, and particularly in the methylenetetrahydrofolate reductase (MTHFR) one, have been often associated with maternal risk for a DS birth as well as with risk of dementia in the elderly. Recent studies pointed out that also changes in MTHFR methylation levels can contribute to human disease, but nothing is known about MTHFR methylation in MDS tissues. We investigated MTHFR promoter methylation in DNA extracted from perypheral lymphocytes of 40 MDS and 44 matched control women that coinceived their children before 35 years of age, observing a significantly increased MTHFR promoter methylation in the first group (33.3 ± 8.1% vs. 28.3 ± 5.8%; p=0.001). In addition, the frequency of micronucleated lymphocytes was available from the women included in the study, was higher in MDS than control mothers (16.1 ± 8.6‰ vs. 10.5 ± 4.3‰; p=0.0004), and correlated with MTHFR promoter methylation levels (r=0.33; p=0.006). Present data suggest that MTHFR epimutations are likely to contribute to the increased genomic instability observed in cells from MDS, and could play a role in the risk of birth of a child with DS as well as in the onset of age related diseases in those women.

/pdf/increased-mthfr-promoter-methylation-in-mothers-of-down-3vesxjzp8c.pdf

Increased MTHFR promoter methylation in mothers of Down syndrome individuals.

Preeclampsia (PE) is a pregnancy specific complication arises in presence of the placenta and disappears immediately after delivery. Therefore, the aim of the present study was to investigate the possible effects of the placental 3′-UTR rs1537514C>G and rs4846049 C>A polymorphisms and DNA methylation of the MTHFR gene on the MTHFR mRNA expression. The placenta of 74 PE pregnant women and 75 normotensive pregnant women were collected after delivery. The methylation status of the MTHFR promoter was assessed with Methylation Specific PCR(MSP). The rs1537514C>G and rs4846049C>A polymorphisms were genotyped using PCR- RFLP method. The mRNA expression levels were measured by Quantitative Real Time PCR. The results showed the lower MTHFR mRNA expression in the placenta of PE women. There was an association between hypermethylation and lower MTHFR mRNA expression in PE women and entire women but not normotensive pregnant women. The frequency of MTHFR rs1537514CG genotype was significantly lower in PE women, however; there was no association between MTHFR rs4846049C>A polymorphism and PE. The combination effects of MTHFR CG/AC genotypes and G-A haplotype of MTHFR rs1537514/ rs4846049 polymorphisms were associated with lower risk of PE. The MTHFR rs1537514G (4869G) allele was associated with higher MTHFR mRNA expression in both groups. However; there was no relation between MTHFR rs4846049C>A polymorphism and MTHFR mRNA expression. Our findings showed lower MTHFR mRNA expression in PE women. The MTHFR rs1537514C>G polymorphism was associated with lower PE risk and MTHFR mRNA expression. Lower expression of MTHFR mRNA was observed in the women with the hypermethylated promoter. This article is protected by copyright. All rights reserved

The association of the placental MTHFR 3'-UTR polymorphisms, promoter methylation, and MTHFR expression with preeclampsia.

We investigated the correlation between 5,10-methylenetetrahydrofolate reductase (MTHFR) gene methylation and pre-eclampsia, and its clinical significance, by comparing methylation in the MTHFR gene promoter of the placenta and peripheral venous blood in pre-eclampsia and normal gravidas. We enrolled 259 gravidas from the People's Liberation Army 202nd Hospital, China, between January 2011 and September 2011, including 127 pre-eclampsia and 132 nor-mal gravidas. Methylation levels of the MTHFR gene in placentas in two sets of gravidas were detected by methylation-specific polymerase chain reaction, plasma homocysteine levels were detected by enzyme-linked immunosorbent assay, and folic acid and vitamin B12 levels were detected by electrochemiluminescence. The chi-square test results were analyzed using the SPSS19.0 statistical software. In placentas, the methylation indices were 26.8% (34/127) and 15.2% (20/132) in the pre-eclampsia and normal groups, respectively (χ(2) = 5.30, P 0.05). Patients with pre-eclampsia have hypermethylation in the MTHFR gene promoter, which may be one of its causes.

/pdf/correlation-between-mthfr-gene-methylation-and-pre-eclampsia-4efdmrk8o9.pdf

Correlation between MTHFR gene methylation and pre-eclampsia, and its clinical significance.

Previous studies have revealed that miRNAs participate in the pathogenesis of ovarian cancer; however, whether miR-600 is also involved remains unclear. In this study, we aimed to investigated the role of miR-600 in ovarian cancer progression. Here, miR-600 expression was significantly upregulated in ovarian cancer tissues and stem cells. Functional studies showed that miR-600 promoted ovarian cancer cell stemness, proliferation and metastasis. Mechanistic studies revealed that Kruppel like factor 9 (KLF9) was indicated as the target of miR-600. The luciferase reporter assay suggested that miR-600 directly bound to the 3'-untranslated region of KLF9. Additionally, miR-600 expression was negatively associated with KLF9 expression in human ovarian cancer tissues. Si-KLF9 partially abolished the discrepancy of self-renewal, growth and metastasis capacity between miR-600 knockdown ovarian cancer cells and control cells. In conclusion, our results suggest that miR-600 promotes ovarian cancer cell stemness, proliferation and metastasis via directly downregulating KLF9, and impairing miR-600 levels may be a new treatment strategy for ovarian cancer in the future. 

/pdf/mir-600-promotes-ovarian-cancer-cells-stemness-proliferation-1p56mcwp.pdf

L L Shan

Papers

Correlation between MTHFR gene methylation and pre-eclampsia, and its clinical significance.

miR-600 promotes ovarian cancer cells stemness, proliferation and metastasis via targeting KLF9