When the sleep cycle-regulating protein hPer2 is disrupted - such as through shift work - it may increase the risk of cancer development, according to researchers.
Lead author Tetsuya Gotoh, of the Department of Biological Sciences at Virginia Polytechnic Institute and State University (Virginia Tech), and colleagues found that a protein that regulates our sleep cycle, or circadian rhythm, also protects against cancer development.
As such, when our circadian rhythm is altered, so is the function of its regulating protein - called human period 2 (hPer2) - which may lead to cancer.
To reach their findings - published in the journalMolecular Biology of the Cell - Gotoh and colleagues analyzed an array of human and animal tumor cells.
They found that hPer2 interacts with a protein called human p53 (hp53) - a known tumor suppressor - in order to regulate cell division.
Suppressing the hPer2 gene, the researchers found, led to abnormal circadian rhythm and uncontrolled cell division.
"When hPer2 is non-functional because it is either mutated or somehow modified, then it is unable to do its job and prevent the cells from dividing at certain times of the day," explains Gotoh. "This is particularly a problem in cases where tumor suppressor genes are mutated, as it happens in more than 80% of all cancer cases."
Findings may lead to new cancer-prevention strategies for shift workers
The team notes that their study provides "the first evidence of direct protein-protein interaction between the clock factor hPer2 and the tumor suppressor hp53."
They add that their findings may lead to new cancer-prevention strategies for individuals who are at increased risk of the disease as a result of disruption to the sleep cycle, such as people who work night shifts.
Commenting on the team's findings, Ignacio Provencio, a professor of biology at the University of Virginia - who was not involved with the research - says:
"Over the past 2 decades we've learned a great deal about the inner workings of the circadian clock, the internal timepiece that controls our sleep-wake cycle and a whole host of other daily bodily rhythms.
The [research team] discovered that a molecular gear of this clock interacts directly with a well-studied protein whose role is to suppress tumor formation. This remarkable finding is likely to provide insight into how disruption of the internal clock can lead to cancer."
The researchers of that study, however, put the association down to the immune system. They found that the immune systems of sleep-disrupted mice were less able to stave off the early stages of cancer than those of control mice.