What happens when your circadian rhythms are out of whack?

Scientists have discovered an important molecular link between lung tumor growth and disrupted circadian rhythms, according to a new paper co-authored by a University of Rochester Wilmot Cancer Institute investigator and led by Scripps Research in California.

Circadian rhythms, sometimes called "biological clocks," are the cellular processes that rule sleep-wake cycles. The World Health Organization states that disrupted circadian rhythms are probable carcinogens.

The latest research, published in the journal Science Advances, describes how the circadian clock gets off track, and implicates a cancer-signature gene known as HSF1 that can trigger lung tumors. Lungs are under tight circadian control and seem to be particularly vulnerable to a disrupted biological clock.

The paper describes in mouse models the role of HSF1 signaling, a previously unknown mechanism that may explain tumor formation in response to rhythm disruption.

The U.S. National Science Foundation-supported findings also suggest that it may be possible to target HSF1 with drug therapy to prevent cancer in people with frequently disturbed circadian rhythms.

Although this study was done in mice, other data link circadian disruption to human tumors, said co-author Brian Altman of the University of Rochester. "Everything points in the same direction," he said. He noted that when the circadian clocks in mice are disrupted by inconsistent sleep, for example, the outcomes are relevant to people who work night shifts or rotating schedules.

"This research focuses on the structure and function of macromolecules and their impacts on biological processes such as immune systems and brain function," says Peter McCartney, a program director in NSF's Division of Biological Infrastructure, which funded the study through a Research Experiences for Undergraduates grant. "This project engages young scientists in fundamental research that can have significant implications for understanding relationships between natural phenomena and human health."