Final answer:
DNA methylation is a biological process that adds a methyl group to DNA, leading to gene silencing and epigenetic modifications that regulate gene expression. This process is important for cellular function and development and can be manipulated for therapeutic purposes, especially in cancer treatment.
Step-by-step explanation:
DNA Methylation
DNA methylation is an epigenetic modification process by which a methyl group is added to the DNA molecule, usually at cytosine bases within CpG islands. This modification often leads to gene silencing as it attracts transcriptional repressors that can bind to methylated regions of DNA. These repressors hinder the binding of transcription factors to DNA, thus inhibiting gene expression. DNA methylation is most commonly used for regulating gene transcription in non-dividing cells or during interphase of the cell cycle, where it contributes to chromatin remodeling.
The epigenetic modification caused by DNA methylation changes the chromatin structure, making it more compact, particularly when DNA regions become hypermethylated with deacetylated histones. This tightly coiled, transcriptionally inactive chromatin leads to gene silencing. The CpG islands within promoter regions are key targets for methylation, which can regulate the inheritance of gene expression patterns from parent to offspring and respond to environmental conditions.
New therapeutic drugs that alter DNA methylation or prevent the removal of acetyl groups from histones are being explored for cancer treatment. By decreasing DNA methylation, these drugs may re-activate silenced genes, including tumor suppressor genes, aiding in killing tumor cells. Understanding gene expression patterns in cancer cells can provide insights into the specific characteristics and potential vulnerabilities of each particular cancer.