Chemo Patients Benefit From Hair Circadian Clock
May 21, 2013

Hair’s Circadian Clock May Help Reduce Hair Loss In Chemo Patients

redOrbit Staff & Wire Reports - Your Universe Online

The discovery that mouse hair operates on a circadian clock has given researchers hope that cancer radiotherapy and chemotherapy could be scheduled later in the day in order to minimize hair loss in patients.

According to the study, which was published online Monday in the Proceedings of the National Academy of Sciences (PNAS), experts from the Salk Institute for Biological Studies, the University of Southern California (USC) and the University of California, Irvine (UCI) have discovered that the rodents undergo a 24-hour cycle of hair growth followed by restorative repair.

They found that mice lost 85 percent of their hair if they received radiotherapy in the morning and just 17 percent if treatment occurred in the evening. The investigators were not only able to pinpoint the exact timing of the hair circadian clock; they also uncovered the biological processes behind the phenomenon — molecules which dictate to hair follicles when it is time to grow and when it is time to repair damage. They then put their findings to the test using radiotherapy.

“These findings are particularly exciting because they present a significant step towards developing new radiation therapy protocols that include minimizing negative side effects on normal tissues, such as hair or bone marrow, while maintaining the desired effects on cancer cells,” said first author Maksim Plikus, an assistant professor of developmental and cell biology at UCI. “We will now apply our findings to design novel circadian rhythm-based approaches to cancer therapy.”

The researchers said that while it will require additional research, they believe they can determine whether their findings will directly translate into human cancer patients. However, they note that it is becoming more and more clear that the body´s organs and tissues have their own circadian clocks, and that learning how they operate could help medical professional better understand exactly when to administer drug therapy to maximize benefits and minimize side effects.

“There are clocks everywhere in the body — clocks that have their own unique rhythm that, we found, have little to do with the central clock in our brains,” explained Satchidananda Panda, co-lead investigator of the study and an associate professor in Salk's Regulatory Biology Laboratory.

“This suggests that delivering a drug to an organ while it is largely inactive is not a good idea. You could do more damage to the organ than when it is awake, repairing and restoring itself,” he added. “If you know when an organ is mending itself, you might be able to deliver more potent doses of a drug or therapy. That might offer a better outcome while minimizing side effects.”