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)

Cancer Clocks as Therapy Target

Thanks to Healthday.com, 11/03

Circadian Rhythms' Effect on Immune Cells: Chemo TOXICITY

Proceeding of the National Acadmeny of Sciences, 2/05

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