Final answer:
Methylation on lysine 9 and lysine 27 of histone H3 (H3K9 and H3K27) leads to gene silencing, which is often observed in cancer cells through a combination of DNA methylation and histone deacetylation, making these epigenetic changes possible targets for therapeutic intervention.
Step-by-step explanation:
The process of epigenetic modification leading to gene silencing can be achieved through DNA methylation and alterations to histone proteins. In the context of histone modifications, methylation on specific lysines on histone proteins can lead to silencing. Particularly, methylation on lysine 9 and lysine 27 of histone H3 (H3K9 and H3K27) is often associated with gene silencing.
In cancer cells, gene silencing is a common epigenetic alteration. Cancer and Epigenetic Alterations typically involve a combination of DNA methylation in CpG islands and histone deacetylation, resulting in a tightly coiled, transcriptionally inactive chromatin structure. Furthermore, the reversal of these epigenetic modifications is a potential therapeutic strategy to reactivate silenced genes in cancer.
Examples of histone methylation leading to silencing are the role of Histone-lysine N-methyltransferase EZH2 in trimethylating H3K27, which is linked to gene silencing. Similarly, DNA methylation in promoter regions is a significant contributor to gene silencing, which can be transmitted through generations or be influenced by environmental factors.