Scientists based at the University of Missouri have discovered that the drug 6-Thioguanine (6-TG) a chemotherapy treatment designed to destroy cancer cells in patients suffering with leukemia, could have a wider application. 6-TG is not currently in common use since medics have turned to other, more modern, drugs to tackle cancer of the blood.
The task of taking one drug, designed for a specific treatment, and using it for other treatments is called “repurposing,” and it is currently a “hot topic” in pharmacology and medicine. Repurposing is about studying a compound or biologic to treat one disease or condition to see if it is safe and effective for treating other diseases.
The re-examination of 6-TG was conducted by Jeffrey Bryan, an associate professor of oncology at the MU College of Veterinary Medicine. Bryan found that 6-TG does not only kill cancer cells, it can also alter how certain cancer cells function. This physiological and biochemical change weakens the cancer cells so they can be more readily killed by other anti-cancer drugs.
This research happened through investigations based on epigenetics. Each cell in the body has particular genetic characteristics called epigenetic markers. These biological markers provide instructions to cells about how to function, when to multiply and when to switch off (or die.) Cancer cells possess epigenetic markers that cause genes to be either switched off or to go out of control. Such markers trigger such cells to grow rapidly, become difficult to kill, and ultimately to harm the body.
By testing the drug on cells taken from dogs with different types of cancer, the Bryan and his science team discovered that 6-TG can affect these epigenetic markers in cancer cells through a chemical process called demethylation (the process of removal of a methyl group from nucleotides in DNA.) This process serves to turn off damaging epigenetic markers and turn on markers that make the cells act in a healthy manner. Bryan hopes that this discovery will lead to new cancer treatments that can be used in conjunction with multiple drugs to tackle cancer from different sides.
Bryan’s work has been published in the journal BMC Veterinary Research. The research is titled “6-Thioguanine and zebularine down-regulate DNMT1 and globally demethylate canine malignant lymphoid cells.”
