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AML/MDS

Posted: Thu Jul 21, 2016 6:50 pm
by hiprock88
From Magic on SA:

From the Yahoo board:
Published on 19/07/2016
"Epigenetic landscape of the TERT promoter: a potential biomarker for high risk AML/MDS":
Telomerase reverse transcriptase promoter;methylation profile;mutation analysis;acute myeloid leukaemia;survival curve
Summary
Although recent observations implicate the importance of telomerase activity in acute myeloid leukaemia (AML), the roles of epigenetic regulations of the TERT gene in leukaemogenesis, drug resistance and clinical prognosis in AML are not fully understood. We developed a quantitative pyrosequencing-based methylation assay covering the TERT proximal promoter and a partial exon 1 (TERTpro/Ex1) region and tested both cell lines and primary leukaemia cells derived from AML and AML with preceding myelodysplastic syndrome (AML/MDS) patients (n = 43). Prognostic impact of methylation status of the upstream TERT promoter region was assessed by the Kaplan–Meier method. The activity of the telomerase inhibitor, imetelstat, was measured using leukaemia cell lines.
The TERTpro/Ex1 region was highly methylated in all cell lines and primary leukaemia cells showed diverse methylation profiles. Most cases showed hypermethylated regions at the upstream TERTpro/Ex1 region, which were associated with inferior patient survival.
TERTpro/Ex1 methylation status was correlated with the cytotoxicity to imetelstat and its combination with hypomethylating agent enhanced the cytotoxicity of imetelstat. AML cell lines and primary blasts harbour distinct TERTpro/Ex1 methylation profiles that could serve as a prognostic biomarker of AML.
However, validation in a large cohort of patients is necessary to confirm our findings.
http://tinyurl.com/zos...

Re: AML/MDS

Posted: Fri Jul 22, 2016 2:33 am
by cheng_ho
Why are these tert promoters in the leukemia cells methylated? In the bulk of genomic DNA, most CpG sites are heavily methylated while CpG islands (sites of CpG clusters) in germ-line tissues and located near promoters of normal somatic cells, remain unmethylated, thus allowing gene expression to occur. When a CpG island in the promoter region of a gene is methylated, expression of the gene is repressed (it is turned off).

Wouldn't we expect the tert promoter region in a cancer cell to be hypomethylated?

Re: AML/MDS

Posted: Sat Jul 23, 2016 11:02 pm
by Fishermangents
Cheng, I am sure it is a good question, but too technical for me to answer. Hopefully somebody with the proper knowledge is able to respond.