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Updated: Jul 13, 2026
Genome-Wide Analysis of DNA Methylation in Gastrointestinal Cancer
Published on: September 18, 2020
Identification of methylation-associated gene expression in neuroendocrine pancreatic tumor cells
Nils Habbe1, Tillmann Bert, Babette Simon
1Department of Gastroenterology and Endocrinology, Philipps-University Marburg, Marburg, Germany. habbe@med.uni-marburg.de
Background:
CpG islands methylation is the main epigenetic modification found in human tumors leading to transcriptional silencing of certain tumor suppressor genes. Reacquisition of p16/CDKN2A tumor suppressor gene expression by 5-aza-2'-deoxycytidine results in concurrent growth inhibition of neuroendocrine pancreatic tumor cells. However, the growth suppressive effects of 5-aza-2'-deoxycytidine is unlikely to be solely attributable to the restored p16/CDKN2A function, but rather a consequence of re-expression of additional genes silenced by de novo methylation. In an effort to validate DNA methylation as an important mechanism in neuroendocrine tumorigenesis and metastatic spread, we attempted to isolate methylation-specific transcripts in neuroendocrine pancreatic tumor cells.
Methods:
Differentially expressed methylation-associated genes were identified by cDNA-representational difference analysis (cDNA-RDA). Differential expression was confirmed by semiquantitative RT-PCR using insert specific primers.
Results:
We identified 48 differently expressed gene fragments and methylation-associated expression was confirmed by semi-quantitative RT-PCR. 52,3% (25 of 48) showed elevated expression levels after 5-aza-2'-deoxycytidine treatment, whereas 47.7% revealed lower expression levels. 7 fragments showed homology to genes with unknown function. Interestingly, 5-aza-2'-deoxycytidine treatment led to re-expression of cofillin whereas matriptase expression levels were significantly lower. Both genes have been associated with metastatic spread and tissue invasion. The other differentially expressed genes play an unknown role in the course of neuroendocrine tumorigenesis.
Conclusion:
DNA methylation appears to be an important molecular mechanism in the process of neuroendocrine pancreatic tumorigenesis and metastatic spread. The definition of DNA methylation patterns associated with neuroendocrine pancreatic tumors might open up the potential for a new sensitive diagnostic tool and might serve as a new antitumor target.
Insights
DNA methylation is crucial in neuroendocrine pancreatic tumors, silencing genes and promoting spread. Identifying these methylation patterns could lead to new diagnostic tools and cancer treatments.
Area of Science:
- Oncology
- Epigenetics
- Molecular Biology
Background:
- DNA methylation, a key epigenetic modification, silences tumor suppressor genes in human cancers.
- 5-aza-2'-deoxycytidine treatment inhibits neuroendocrine pancreatic tumor cell growth by restoring p16/CDKN2A expression.
- Tumor suppressor gene re-expression is likely due to additional silenced genes, not just p16/CDKN2A, being reactivated.
Purpose of the Study:
- To investigate DNA methylation as a mechanism in neuroendocrine pancreatic tumorigenesis and metastasis.
- To identify specific gene transcripts affected by DNA methylation in these tumors.
Main Methods:
- cDNA-representational difference analysis (cDNA-RDA) to identify differentially expressed methylation-associated genes.
- Semi-quantitative RT-PCR with insert-specific primers to confirm differential gene expression.
Main Results:
- 48 differentially expressed gene fragments were identified and confirmed via RT-PCR.
- 52.3% of genes showed increased expression, while 47.7% showed decreased expression after 5-aza-2'-deoxycytidine treatment.
- Re-expression of cofillin and reduced matriptase levels were observed, both linked to metastasis and invasion.
Conclusions:
- DNA methylation is a significant factor in neuroendocrine pancreatic tumor development and spread.
- Characterizing DNA methylation patterns could yield novel diagnostic markers for these tumors.
- These findings may pave the way for new therapeutic targets in neuroendocrine pancreatic cancer treatment.
