Clocking Cancer

Les Lang at the UNC Medical Center News Office now writes a blog - Hard Science. One recent post immediately caught my eye - Clocking Cancer:

You might say that Dr. Aziz Sancar is trying to clock cancer.

In a nifty double play involving a pair of recent publications in the Proceedings of the National Academy of Sciences (PNAS), the Sarah Graham Kenan professor of biochemistry and biophysics at UNC found in one study that tinkering with the circadian clock can suppress cancer growth, and in the other he and his lab team presented molecular data suggesting why timing just might be everything with regard to delivering chemotherapy for cancer.

Both studies involve the daily oscillatory rhythms of the cellular repair machinery. The main driver of these rhythms is the circadian clock, which keeps the biological, behavioral and physiological processes on a 24-hour cycle. Every cell in the body has its own internal clock, and each is synchronized by one master clock, located in a neuronal cluster in the brain. (No wonder we feel wound up sometimes.)

In the latter research, the Sancar team found that the ability of the cellular repair sytem known as nucleotide excision repair is linked to the circadian clock. Repair ability is at a minimum in the early morning and reaches a maximum in the evening hours. Moreover, this daily dance is due to changes in the levels of just one of six repair machinery components, an enzyme, at different times of day.

Of importance here is that the repair machinery in question usually fixes damage to DNA caused by chemotherapy or UV radiation exposure. So although the study involved murine brain tissue, chemotherapy delivery may be best early in the morning (6:00 a.m. to 10:00 a.m.).

Dr.Sankar explains the study in this video: