Researchers at Washington University School of Medicine in St. Louis uncovered this biochemical switch in a protein called Bcl-xL, according to a study in current issue of Cell.
DNA-damaged chemotherapy drugs are carried in the blood and work by gumming up DNA in rapidly-dividing tumor cells. That damage to the DNA causes the tumor cells to self-destruct through a process called apoptosis.
The drugs can also trigger apoptosis in healthy cells that are rapidly dividing, such as hair follicle cells. But the drugs don't trigger apoptosis in normal healthy cells that aren't dividing. The researchers wanted to find out the reasons for that.
"Our findings show that normal cells somehow suppress the signal that throws the switch and avoid self-destructing," says researcher Dr. Steve J. Weintraub, an assistant professor of surgery, medicine and cell biology and physiology.
Find out more about chemotherapy at the U.S National Cancer Institute.