scholarly journals A stem cell–like chromatin pattern may predispose tumor suppressor genes to DNA hypermethylation and heritable silencing

2007 ◽  
Vol 39 (2) ◽  
pp. 237-242 ◽  
Author(s):  
Joyce E Ohm ◽  
Kelly M McGarvey ◽  
Xiaobing Yu ◽  
Linzhao Cheng ◽  
Kornel E Schuebel ◽  
...  
Keyword(s):  
Stem Cell ◽  
Tumor Suppressor ◽  
Tumor Suppressor Genes ◽  
Dna Hypermethylation ◽  
Suppressor Genes ◽  
Chromatin Pattern

scholarly journals The role of XPC protein deficiency in tobacco smoke-induced DNA hypermethylation of tumor suppressor genes

2013 ◽  
Vol 03 (04) ◽  
pp. 285-293 ◽  
Author(s):  
Gan Wang ◽  
Le Wang ◽  
Vanitha Bhoopalan ◽  
Yue Xi ◽  
Deepak K. Bhalla ◽  
...  
Keyword(s):  
Tumor Suppressor ◽  
Tobacco Smoke ◽  
Tumor Suppressor Genes ◽  
Protein Deficiency ◽  
Dna Hypermethylation ◽  
Suppressor Genes

Strategies to Re-Express Epigenetically-Silenced Tumor Suppressor Genes Converge on the Requirement for Inhibition of the Histone Methyltransferase SUV39H1.

Blood ◽  
2008 ◽  
Vol 112 (11) ◽  
pp. 3357-3357
Author(s):  
Asha Lakshmikuttyamma ◽  
Stuart Scott ◽  
David P. Sheridan ◽  
John DeCoteau ◽  
Ron Geyer
Keyword(s):  
Tumor Suppressor ◽  
Cell Lines ◽  
Tumor Suppressor Genes ◽  
Fold Increase ◽  
Dna Demethylation ◽  
Dna Hypermethylation ◽  
Suppressor Genes ◽  
Promoter Dna Methylation ◽  
Promoter Dna ◽  
E Cadherin

Abstract Gene silencing mediated by aberrant promoter DNA hypermethylation represents a key mechanism by which tumor suppressor gene expression is silenced in cancer and it is associated with multiple repressive histone modifications. Histone H3 lysine 9 (H3K9) methylation is a key repressive chromatin modification with important implications for regulating cell proliferation, differentiation, and gene expression. SUV39H1 is a methyltransferase that catalyzes the addition of trimethyl groups to H3K9. SUV39H1 is associated with regions of hypermethylated CpG islands, with repressive complexes, such as RB/E2F, and with DNA-binding proteins involved in leukemogenesis, such as AML1 and PML-RAR, where its H3K9 trimethylation activity promotes heterochromatin formation and gene silencing. We studied the requirement of SUV39H1 in the epigenetic silencing of heavily methylated tumor suppressor genes p15INK4B and E-cadherin in acute myeloid leukemia (AML). Treatment of AML cell lines AML193, KG1a, and Kasumi with the DNA methyltransferase (DNMT) inhibitor 5-Aza-2’-deoxycytidine (5-Aza-dC) induces p15INK4B and E-cadeherin re-expression in association with dramatic decreases in p15INK4B and E-cadherin promoter DNA methylation and marked reductions in the levels of SUV39H1 and H3K9 trimethylation at these promoters. Interestingly, treatment of these cell lines with SUV39H1 shRNA, or the SUV39H1 inhibitor chaetocin, also induces p15INK4B and E-cadherin re-expression and H3K9 demethylation, without affecting promoter DNA methylation. Thus, re-expression of hypermethylated tumor suppressors requires histone H3K9 demethylation, which can be achieved indirectly by decreasing the amount of SUV39H1 associated with the promoter using 5-Aza-dC, or directly by inhibiting SUV39H1 expression or activity without requiring promoter DNA demethylation. Furthermore, we found that SUV39H1 shRNA or chaetocin in combination with 5-Aza-dC acts synergistically to re-express epigenetically silenced p15INK4B and E-cadherin in AML cell lines. Treatment of primary human AML blasts obtained from two patients with combinations of 5-Aza-C and chaetocin also results in synergistic re-expression of p15INK4B and E-cadherin (2–6 fold increase with 5-Aza-C or chaetocin treatment vs. 11–14 fold increase with co-treatment). Our study has important implications for developing novel epigenetic therapies of relevance to AML as it suggests that the re-expression of tumor suppressor genes silenced by aberrant promoter DNA hypermethylation converges on the requirement for SUV39H1 and H3K9 methylation inhibition but not promoter DNA demethylation. Our finding that SUV39H1 inhibition may function synergistically with DNMT inhibitors to enhance gene reactivation and chromatin changes also highlights the needs for developing more inhibitors of histone methyltransferases and for performing detailed drug interaction studies to identify the best drug combinations for optimal epigenetic therapies.

scholarly journals Germline Stem Cell Activity Is Sustained by SALL4-Dependent Silencing of Distinct Tumor Suppressor Genes

2017 ◽  
Vol 9 (3) ◽  
pp. 956-971 ◽  
Author(s):  
Ai-Leen Chan ◽  
Hue M. La ◽  
Julien M.D. Legrand ◽  
Juho-Antti Mäkelä ◽  
Michael Eichenlaub ◽  
...  
Keyword(s):  
Stem Cell ◽  
Tumor Suppressor ◽  
Tumor Suppressor Genes ◽  
Cell Activity ◽  
Germline Stem Cell ◽  
Suppressor Genes ◽  
Stem Cell Activity

scholarly journals Consistent DNA Hypermethylation Patterns in Laryngeal Papillomas

2010 ◽  
Vol 1 (2) ◽  
pp. 69-77 ◽  
Author(s):  
Josena K Stephen ◽  
Kang Mei Chen ◽  
Veena Shah ◽  
Vanessa G Schweitzer ◽  
Glendon Gardner ◽  
...  
Keyword(s):  
Dna Methylation ◽  
Tumor Suppressor ◽  
Tumor Suppressor Genes ◽  
Methylation Status ◽  
Promoter Hypermethylation ◽  
Aberrant Methylation ◽  
Dna Hypermethylation ◽  
Suppressor Genes ◽  
Multiple Tumor ◽  
Specific Pcr

Abstract Introduction This study examined the contribution of promoter hypermethylation to the pathogenesis of respiratory papillomatosis (RP), including recurrences (RRP) and progression to squamous cell carcinoma (SSC). Materials and methods A retrospective cohort of 25 laryngeal papilloma cases included 21 RRP, two of which progressed to SCC. Aberrant methylation status was determined using the multigene (22 tumor suppressor genes) methylation-specific multiplex ligationdependent probe amplification assay and confirmed using methylation specific PCR. Results Twenty genes had altered DNA methylation in 22 of 25 cases. Aberrant methylation of CDKN2B and TIMP3 was most frequent. Promoter hypermethylation of BRCA2, APC, CDKN2A and CDKN2B was detected in 2 RRP cases with subsequent progression to SCC. Of the 25 cases, 22 were positive for HPV-6, 2 for HPV-11 and 1 for HPV-16 and 33. Conclusion Consistent aberrant methylation of multiple tumor suppressor genes contributes to the pathogenesis of laryngeal papillomas. Persistent aberrant DNA methylation events in 2 RRP cases that progressed to cancer indicate an epigenetic monoclonal progression continuum to SCC.

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