Tumorigenesis:Clockwork Kristine Novak The daily oscillations of biological processes, known as circadian rhythms, are regulated by genetically controlled endogenous clocks. Disruptions in circadian rhythms have been associated with cancer - people and animals with irregular sleep-wake cycles are more susceptible to certain cancers, and the efficacy and toxicity of some chemotherapy agents correlate with the timing of drug delivery. A recent study by Fu et al. reported that mice with targeted disruption in a circadian control gene develop tumours, providing the opportunity to study the molecular basis of this relationship. So far, eight core circadian genes have been identified. Among these are the Per1, 2 and 3 genes, which encode non-DNA-binding nuclear factors. The expression of these genes oscillates over the 24-hour circadian period. Mice with a homozygous mutation in Per2 (mPer2m/m) have been previously reported to be deficient in circadian clock function. In the 4 October issue of Cell, Fu et al. report that these mice have neoplastic phenotypes, such as salivary-gland hyperplasia and teratoma formation, reduced levels of thymic apoptosis . Nature Reviews Cancer (2002) Thanks to Healthday.com, 11/03 Proceeding of the National Acadmeny of Sciences, 2/05 Remember we are NOT Doctors and have NO medical training. This site is like an Encylopedia - there are many pages, many links on many topics. Support our work with any size DONATION - see left side of any page - for how to donate. You can help raise awareness of CAM.