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Updated: Dec 25, 2025
Methyl-binding DNA capture Sequencing for Patient Tissues
Published on: October 31, 2016
Demethylation Status of Somatic DNA Extracted From Pituitary Neuroendocrine Tumors Indicates Proliferative Behavior
Borbála Szabó1,2, Kinga Németh3, Katalin Mészáros3
12nd Department of Internal Medicine, Semmelweis University, Budapest, Hungary.
Background:
Cytosine intermediaries 5-methylcytosine (5mC) and 5-hydroxymethylcytosine (5hmC), epigenetic hallmarks, have never been investigated in pituitary neuroendocrine tumors (PitNET).
Objective:
To examine methylation-demethylation status of global deoxyribonucleic acid (DNA) in PitNET tissues and to assess its correlation with clinical and biological parameters.
Materials And Methods:
Altogether, 57 PitNET and 25 corresponding plasma samples were collected. 5mC and 5hmC were investigated using liquid chromatography-tandem mass spectrometry. Expression of DNA methyltransferase 1 (DNMT1); tet methylcytosine dioxygenase 1 through 3 (TET1-3); and ubiquitin-like, containing PHD and RING finger domains 1 and 2 (UHRF1-2) were measured by reverse transcription-polymerase chain reaction. Levels of 5hmC and UHRF1-2 were explored by immunohistochemistry. Effect of demethylating agent decitabine was tested on pituitary cell lines.
Results:
5hmC/5mC ratio was higher in less differentiated PitNET samples. A negative correlation between Ki-67 proliferation index and 5hmC, 5hmC to 5mC ratio were revealed. Higher 5mC was observed in SF-1 + gonadotroph adenomas with a higher Ki-67 index. Expressions of TET2 and TET3 were significantly higher in adenomas with higher proliferation rate. UHRF1 showed gradually increased expression in higher proliferative adenoma samples, and a significant positive correlation was detected between UHRF2 expression and 5hmC level. Decitabine treatment significantly decreased 5mC and increased 5hmC levels in both cell lines, accompanied with decreased cell viability and proliferation.
Conclusion:
The demethylation process negatively correlated with proliferation rate and the ratio of 5hmC to 5mC was higher in less differentiated adenomas. Therefore, epigenetic markers can be potential biomarkers for PitNET behavior. Altering the epigenome in adenoma cells by decitabine decreased proliferation, suggesting that this treatment might be a novel medical treatment for PitNET.
Insights
Epigenetic modifications, including 5-methylcytosine (5mC) and 5-hydroxymethylcytosine (5hmC), were analyzed in pituitary neuroendocrine tumors (PitNET). Findings suggest these epigenetic markers correlate with tumor behavior and may offer novel therapeutic targets.
Area of Science:
- Endocrinology
- Epigenetics
- Oncology
Background:
- Epigenetic modifications like 5-methylcytosine (5mC) and 5-hydroxymethylcytosine (5hmC) are crucial in cellular function.
- These epigenetic marks have not been previously studied in pituitary neuroendocrine tumors (PitNET).
Purpose of the Study:
- To investigate the global DNA methylation and demethylation status in PitNET tissues.
- To correlate these epigenetic changes with clinical and biological characteristics of PitNET.
Main Methods:
- Analysis of 5mC and 5hmC levels in 57 PitNET and 25 plasma samples using liquid chromatography-tandem mass spectrometry.
- Measurement of DNA methyltransferase (DNMT1), TET methylcytosine dioxygenase (TET1-3), and UHRF1-2 gene expression via RT-PCR.
- Assessment of decitabine's effect on pituitary cell lines.
Main Results:
- A higher 5hmC/5mC ratio was observed in less differentiated PitNET.
- The 5hmC level and 5hmC/5mC ratio negatively correlated with the Ki-67 proliferation index.
- Decitabine treatment reduced 5mC, increased 5hmC, and decreased cell viability and proliferation in pituitary cell lines.
Conclusions:
- Demethylation processes are inversely related to proliferation rates in PitNET.
- Epigenetic markers like 5hmC and 5mC show potential as biomarkers for predicting PitNET behavior.
- Targeting the epigenome with agents like decitabine may represent a novel therapeutic strategy for PitNET.
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