Figure 2.

Epigenetic alterations in cancer cells. In non-neoplasic cells, CpG islands of tumor suppressor gene promoters are generally unmethylated and acetylated, resulting in transcriptional activation and expression. In contrast, non-coding regions and repetitive elements are hypermethylated, ensuring chromosome stability. Gene bodies are normally methylated, enhancing transcription. Neoplasic cells are characterized by global hypomethylation and local CpG island hypermethylation, especially at tumor suppressor gene promoters, resulting in aberrant transcription and genomic instability.