Tagging DNA: Mislabelling the Cancer Genome


your body is made up of billions of tiny cells cells that work together to make up tissues organs and systems almost every cell in your body contains the same DNA the same DNA code so how can cells that contain the same DNA be so different what makes a bone cell a bone cell or a liver cell a liver cell different cells use the information contained within the DNA in different ways some parts of the DNA in one cell will be active but not in another this genetic information is encoded within the letters or bases of our DNA sequence inside ourselves DNA is wrapped around proteins called histones the DNA can be loose allowing genes to be switched on or it can be tight causing genes to be switched off one of the ways genes can be switched off is by adding tiny chemical tags called methyl groups shown here as bright particles here the enzyme dnmt attaches to the DNA and a methyl group is transferred to a cytosine base that has rotated out from the DNA strand this process called methylation mainly occurs where cytosine is followed by guanine or CPG sites each cell type has a unique pattern of methylation and unlike the DNA sequence which cannot be easily changed the methylation or epigenetic pattern can be altered methylation and D methylation of DNA occurs in a delicate balance that is potentially influenced by environmental triggers such as diet or disease to affect gene expression here we see the enzyme tet binding to methylated DNA and causing a chemical change to the metal tag in cancer the pattern of methylation changes the DNA becomes highly disorganized as methyl groups are added and removed from the DNA these causes some genes that should be off to be switched on and some genes that should be on to be switched off although it is not possible to reverse the genetic changes that occur in cancer the epigenetic changes can potentially be reversed with drug treatment epigenetic changes can also be used to identify cancer DNA for early detection and monitoring disease progression cancer drug treatments that target these epigenetic mistakes offer new and exciting ways to treat cancer giving hope to current and future cancer patients

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