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Detection of Modified Forms of Cytosine Using Sensitive Immunohistochemistry
Published on: August 16, 2016
Detection of DNA methylation. Potential applications to diagnostic cytopathology
1Division of Cytopathology, Department of Pathology, Johns Hopkins Medical Institutions, Baltimore, Maryland, USA.
Abstract:
Inactivation of tumor suppressor genes is often the result of genetic mutations or deletions. However, another mechanism for silencing genes involves DNA methylation. In this setting, a methyl group is added to cytosine residues within the gene promoter region; that prevents transcription. Tumors usually contain multiple genes that have been silenced by methylation, unlike normal tissues, in which gene methylation events are less common. The list of genes methylated in a given tumor is often referred to as a gene methylation profile. Gene methylation profiles may be almost unique for each type of tumor. Methylation-specific polymerase chain reaction is a sensitive technique that can detect gene methylation in cytologic samples. Application of this technique to cytologic cancer screening tests may increase their sensitivity. Also, the introduction of novel chemotherapeutic drugs that target DNA methylation may utilize gene methylation assays on fine needle aspiration biopsies of tumors.
Insights
Gene methylation, a process silencing tumor suppressor genes, is common in cancers. Methylation-specific PCR can detect these changes in cytologic samples, improving cancer screening and guiding targeted therapies.
Area of Science:
- Molecular Biology
- Cancer Genetics
- Epigenetics
Background:
- Tumor suppressor gene inactivation is crucial in cancer development.
- Mechanisms include genetic mutations, deletions, and epigenetic silencing via DNA methylation.
- DNA methylation involves adding methyl groups to cytosine, inhibiting gene transcription.
Purpose of the Study:
- To explore DNA methylation as a mechanism for gene silencing in tumors.
- To highlight the potential of gene methylation profiles in cancer diagnostics.
- To assess the utility of methylation-specific PCR in cancer screening and therapy.
Main Methods:
- Review of DNA methylation mechanisms in gene silencing.
- Description of gene methylation profiles in tumors versus normal tissues.
- Introduction to methylation-specific polymerase chain reaction (PCR) for detecting gene methylation.
Main Results:
- Tumors exhibit widespread gene silencing through methylation, unlike normal tissues.
- Gene methylation profiles can be highly specific to tumor types.
- Methylation-specific PCR is a sensitive method for detecting gene methylation in cytologic samples.
Conclusions:
- DNA methylation is a significant mechanism for tumor suppressor gene inactivation in cancer.
- Gene methylation profiling offers potential for tumor-specific diagnostics.
- Methylation-specific PCR can enhance cancer screening sensitivity and inform novel therapeutic strategies targeting DNA methylation.
