February 5, 2009

Disrupting circadian clock may slow cancer

Disrupting the body's time-keeping system, the circadian clock, may help slow cancer growth, U.S. researchers say.

In a mouse model used to investigate cancer, genetically altering one of four essential clock genes suppressed cancer growth -- perhaps due to intracellular signals that make cancer cells more likely to commit cell suicide -- a process known as apoptosis.

Adjusting the clock in this way could certainly be a new target for cancer treatment, senior study author Dr. Aziz Sancar of the University of North Carolina at Chapel Hill said in a statement. Our study indicates that interfering with the function of these clock genes in cancer tissue may be an effective way to kill cancer cells, and could be a way to improve upon traditional chemotherapy.

The findings appear online in the Proceedings of the National Academy of Sciences.

Previous research had linked disruption of body's natural circadian rhythms to the increased incidence of cancer in night-shift nurses and transatlantic flight attendants.

Sancar and colleagues found altering the clock gene did not predispose a normal mouse model to cancer, so in this study they disrupted the clock gene in mice with a defect in the P53 gene predisposing them to cancer, and found it actually extended life by 50 percent, the researchers say.