scholarly journals Multiplexed profiling of candidate genes for CpG island methylation status using a flexible PCR/LDR/Universal Array assay

2005 ◽  
Vol 16 (2) ◽  
pp. 282-289 ◽  
Author(s):  
Y.-W. Cheng
Keyword(s):  
Candidate Genes ◽  
Cpg Island ◽  
Methylation Status ◽  
Universal Array ◽  
Cpg Island Methylation

scholarly journals CpG Island Methylation of the MLH1, MGMT, DAPK, and CASP8 Genes in Cancerous and Adjacent Noncancerous Stomach Tissues

Medicina ◽  
2013 ◽  
Vol 49 (8) ◽  
pp. 56
Author(s):  
Rita Kupčinskaitė-Noreikienė ◽  
Jurgita Skiecevičienė ◽  
Laimas Jonaitis ◽  
Rasa Ugenskienė ◽  
Juozas Kupčinskas ◽  
...  
Keyword(s):  
Gastric Adenocarcinoma ◽  
Cpg Island ◽  
Methylation Status ◽  
Inverse Correlation ◽  
Clinicopathological Characteristics ◽  
Tnm Staging ◽  
Tumor Type ◽  
Gene Promoters ◽  
Methylation Frequency ◽  
Cpg Island Methylation

Background and Objective. Many factors are involved in the development of gastric adenocarcinoma. The CpG island methylation of apoptosis and mismatch repair genes by the loss of their function is important in gastric adenocarcinoma. The aim of this study was to determine the methylation frequency of MLH1, MGMT, CASP8, and DAPK in cancerous and adjacent noncancerous stomach tissues, to determine possible associations with the selected clinicopathological characteristics, and to identify possible correlation between the methylation of individual genes. Material and Methods. The methylation status of MLH1, MGMT, DAPK, and CASP8 was investigated in 69 patients with gastric adenocarcinoma by using methylation-specific polymerase chain reaction. The associations between patients’ clinical characteristics and methylation status were assessed. Results. The methylation frequency of the MLH1, DAPK, MGMT, and CASP8 gene promoters in cancerous and adjacent noncancerous tissues was 31.9% and 27.5%; 47.8% and 46.4%; 36.2% and 44.9%; and 5.8% and 5.8%, respectively, but the differences were not significant. There was no significant association between the methylation status of the mentioned genes and clinicopathological characteristics, such as age, sex, tumor type by the Lauren classification, degree of differentiation G, and TNM staging. An inverse correlation between the methylation of the DAPK and MLH1 gene promoters in cancerous and surrounding noncancerous tissues was found. Conclusions. The methylation of the MLH1, MGMT, DAPK, and CASP8 genes was found to occur both in cancerous and noncancerous stomach tissues. These findings provide additional insights into gene methylation patterns in gastric adenocarcinoma.

scholarly journals Epigenomic Silencing of the BMP-4 Gene in Pituitary Adenomas: A Potential Target for Epidrug-Induced Re-expression

Endocrinology ◽  
2012 ◽  
Vol 153 (8) ◽  
pp. 3603-3612 ◽  
Author(s):  
Kiren Yacqub-Usman ◽  
Cuong V. Duong ◽  
Richard N. Clayton ◽  
William E. Farrell
Keyword(s):  
Cpg Island ◽  
Trichostatin A ◽  
Expression Patterns ◽  
Methylation Status ◽  
Hormone Secretion ◽  
Treatment Strategies ◽  
Histone Tail ◽  
Histone Deacetylase Inhibitor Trichostatin ◽  
Cpg Island Methylation ◽  
New Treatment

Bone morphogenetic protein (BMP)-4 is a key mediator of anterior pituitary organogenesis. However, through inappropriate expression patterns, BMP-4 is also pathogenic in a pituitary adenoma subtype-specific context. In these cases, increase or decrease in BMP-4 in lactotroph- and corticotroph-derived adenomas, respectively, is consistent with a bifunction role for this protein toward either promotion or inhibition of cell proliferation and hormone secretion. To gain insight into the aberrations responsible for differential expression, we examined BMP-4 transcript and protein expression patterns in the major adenomas subtypes. BMP-4 transcript and protein are differentially expressed and show increase in the majority of prolactinomas relative to normal pituitary, whereas the majority of other adenoma subtypes show reduced expression relative to both prolactinoma and normal pituitaries. Reduced expression of BMP-4 is not associated with change in CpG island methylation status. However, histone tail modifications are apparent, as enrichment for a modification associated with silent genes, H3K27me3, and depletion of a modification associated with active genes, H3K9Ac. In pituitary cell lines, reduced BMP-4 expression is also associated with similar histone tail modifications and contemporaneous increase in CpG island methylation. In these cells, coincubation with the demethylating agent zebularine and histone deacetylase inhibitor, trichostatin A, reversed epigenetic changes and restored expression of BMP-4. These studies show that, in contrast to prolactinomas, other adenoma subtypes show reduced expression of BMP-4 where epidrug induced reexpression, alone or in combination with conventional therapies, may offer new treatment strategies.

scholarly journals De novo methylation of CpG island sequences in human fibroblasts overexpressing DNA (cytosine-5-)-methyltransferase.

1996 ◽  
Vol 16 (8) ◽  
pp. 4555-4565 ◽  
Author(s):  
P M Vertino ◽  
R W Yen ◽  
J Gao ◽  
S B Baylin
Keyword(s):  
Enzyme Activity ◽  
De Novo ◽  
Cpg Island ◽  
Human Fibroblasts ◽  
Methylation Status ◽  
Cpg Islands ◽  
Parental Cell Line ◽  
Direct Role ◽  
Cpg Island Methylation ◽  
De Novo Methylation

Recent studies showing a correlation between the levels of DNA (cytosine-5-)-methyltransferase (DNA MTase) enzyme activity and tumorigenicity have implicated this enzyme in the carcinogenic process. Moreover, hypermethylation of CpG island-containing promoters is associated with the inactivation of genes important to tumor initiation and progression. One proposed role for DNA MTase in tumorigenesis is therefore a direct role in the de novo methylation of these otherwise unmethylated CpG islands. In this study, we sought to determine whether increased levels of DNA MTase could directly affect CpG island methylation. A full-length cDNA for human DNA MTase driven by the cytomegalovirus promoter was constitutively expressed in human fibroblasts. Individual clones derived from cells transfected with DNA MTase (HMT) expressed 1- to 50-fold the level of DNA MTase protein and enzyme activity of the parental cell line or clones transfected with the control vector alone (Neo). To determine the effects of DNA MTase overexpression on CpG island methylation, we examined 12 endogenous CpG island loci in the HMT clones. HMT clones expressing > or = 9-fold the parental levels of DNA MTase activity were significantly hypermethylated relative to at least 11 Neo clones at five CpG island loci. In the HMT clones, methylation reached nearly 100% at susceptible CpG island loci with time in culture. In contrast, there was little change in the methylation status in the Neo clones over the same time frame. Taken together, the data indicate that overexpression of DNA MTase can drive the de novo methylation of susceptible CpG island loci, thus providing support for the idea that DNA MTase can contribute to tumor progression through CpG island methylation-mediated gene inactivation.

Mechanisms of Telomere Maintenance Dysfunction in B-Chronic Lymphocytic Leukemia Through CpG Island Methylation

Blood ◽  
2012 ◽  
Vol 120 (21) ◽  
pp. 3489-3489 ◽  
Author(s):  
Morgan Auchter ◽  
Sandrine Medves ◽  
Laetitia Chambeau ◽  
Sophie Gazzo ◽  
Etienne Moussay ◽  
...  
Keyword(s):  
Chronic Lymphocytic Leukemia ◽  
Telomere Length ◽  
Dna Sequences ◽  
Conflicts Of Interest ◽  
Cpg Island ◽  
Methylation Status ◽  
Telomerase Activity ◽  
Lymphocytic Leukemia ◽  
Telomere Maintenance ◽  
Cpg Island Methylation

Abstract Abstract 3489 Telomeres are a repetitive DNA sequences associated with a protein complex named shelterin that protect chromosome ends. Two types of mechanisms maintain telomere in cancer cells. The first involves telomerase an enzyme able to copy the telomeric motif that consists of three principal subunits, including the telomerase reverse transcriptase hTERT. The second, named ALT (Alternative Lengthening of Telomere), corresponds to the recombination between telomeres that involves notably a complex formed by the topoisomerase III alpha (hTopoIIIa), BLM, RMI1 and RMI2. Little is known about the involvement of the ALT mechanism in B-chronic lymphocytic leukemia (B-CLL). In fact this leukemic disease shows low telomerase activity, shelterin defect and telomeric dysfunction. In an effort to characterize ALT cells from 31 B-CLL patients, we analyzed their telomere length and telomerase activity. B-CLL patients showed almost no hTERT transcript (detected in three cases), low telomerase activity (detected in 7 cases) and a telomere average size ranging from 3 to 10 kb. Moreover, a strong deregulation of genes encoding three shelterin proteins, TRF1, TRF2, Pot1, and an at least two fold downregulation of hTopoIIIa gene expression in 21 cases were observed, suggesting the presence of a telomere maintenance dysfunction affecting both mechanisms, telomerase dependent and ALT. CpG island methylation has been mapped for both promoters and if hTERT shows a disseminated methylation profile in 22 patients, for hTopoIIIα we identified nine CpG upstream the minimal promoter, being methylated in 19 of our 31 analyzed patients. We then performed luciferase experiments and we showed that methylation in this 9 CpG induced a strong inhibition of hTopoIIIa transcription. Finally we correlated telomere length and hTopoIIIa methylation status as we observed that 25.4% of the hTopoIIIa promoters were methylated in patients with shorter chromosomes and only 11.1 % were methylated in patients with longer telomeres (p<0.0025). As nearly no telomerase activity have been detected in our patients and as downregulation of hTopoIIIa could increase recombination rate between sister chromatid, methylation of hTERT and hTopoIIIa promoter CpG islands may lead to telomere dysfunction and increased genetic instability in B-CLL. Disclosures: No relevant conflicts of interest to declare.

Sign in / Sign up

Export Citation Format

Share Document