Chronodisruption, cell cycle checkpoints and DNA repair.

Chronodisruption, a disturbance in "natural" daily light/dark regulation, is possibly linked to disturbances in cell cycle homeostasis. The association and the synchronization between circadian rhythms and mitosis are not yet clear. The circadian oscillator is involved in the major cellular pathways of cell division. A molecular link between the circadian clock and the mammalian DNA damage checkpoints has been outlined. Analyses suggest an association between light disruption and obstruction of the cell cycle homeostasis. Disruption in the homeostatic control of the cell cycle has been associated with cancer and acceleration of malignant growth, possibly as a result of the interruption of DNA damage check-points. Studies further indicate that light signal during the dark phase affects the transcription level of a substantial number of genes that are associated with cell cycle progression, cell proliferation and tumorigenesis. Indeed, the International Agency for Research in Cancer categorized "shift work that involves circadian disruption" as possibly carcinogenic. In this review the current finding on light pollution and its potential influence on cell cycle check-points and DNA repair is presented.