Stem Cells May Help Control Cancer

The development of cancer and a host of other diseases is controlled by certain genes, which are either turned on or off to promote or inhibit progress. Researchers in the United States have just recently finished mapping a DNA modification in stem cells, whose power could be harnessed for new cures.

University of California in Los Angeles (UCLA) experts completed the first genome-wide mapping of 5-hydroxymethylcytosine (5hmC). This is a modification in deoxyribonucleic acid (DNA) that is often referred to as the sixth nucleotide.

DNA is made up of four letters, or nucleotides, called adenine (A), guanine (G), cytosine (C) and thymine (T). RNA substitutes one of these letters for uracil (U). These are the five known letters, and 5hmC is colloquially referred to as the sixth.

What is remarkable about this molecule is that it's most often found in genes that are active, or turned on. Now that the new map is complete, experts know where 5hmC is found in the genome at all times.

Controlling this molecule could enable researchers to develop new ways of keeping cancer in check, in addition to other conditions where gene expression dictates the course of development. Granted, it will take a few years for this to happen, but at least now experts have something to go on.

The investigation was conducted by scientists at the UCLA Eli and Edythe Broad Center of Regenerative Medicine and Stem Cell Research. Details of the work are published in the July issue of the medical journal Genome Biology.

The paper explains that 5hmC is formed following a process called DNA methylation, during which a single methyl group is added to cytosine. After this process concludes, an extra hydroxy group is added to the nucleotide as well.

This newly developed hydroxymethyl group can then switch certain genes on or off. It is conceivable that future therapies against a wide array of conditions could rely on forcing this switch to turn genes favoring the development of a condition off.

“Any way you can control genes will be hugely important for human disease and cancer. Cancer is generally a problem of genes being inappropriately turned off or mutated, like tumor suppressors genes, or genes that should be off getting switched on,” Steven E. Jacobsen explains.

The expert is a Howard Hughes Medical Institute investigator, and a professor of molecular, cell and developmental biology at the UCLA Division of Life Sciences. He says that the new work provides geneticists with a map of where 5hmC is located in the genome.

“That is important to know, because it helps you to understand how it is functioning and what it's being used for,. We had known that DNA could be modified by 5hmC, but it wasn't clear where on the genome this was occurring,” he concludes.

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