title: Circadian clocks, epigenetics, and cancer.
abstract: OBJECTIVE
  The interplay between circadian rhythm and cancer has been suggested for more than a decade based on the observations that shift work and cancer incidence are linked. Accumulating evidence implicates the circadian clock in cancer survival and proliferation pathways. At the molecular level, multiple control mechanisms have been proposed to link circadian transcription and cell-cycle control to tumorigenesis.
  
  
  RESULTS
  The circadian gating of the cell cycle and subsequent control of cell proliferation is an area of active investigation. Moreover, the circadian clock is a transcriptional system that is intricately regulated at the epigenetic level. Interestingly, the epigenetic landscape at the level of histone modifications, DNA methylation, and small regulatory RNAs are differentially controlled in cancer cells. This concept raises the possibility that epigenetic control is a common thread linking the clock with cancer, though little scientific evidence is known to date.
  
  
  CONCLUSIONS
  This review focuses on the link between circadian clock and cancer, and speculates on the possible connections at the epigenetic level that could further link the circadian clock to tumor initiation or progression.
authors.affiliation: Department of Biological Chemistry, Center for Epigenetics and Metabolism, University of California, Irvine, Irvine, California, USA.
authors.forename: Selma
authors.initials: S
authors.lastname: Masri
authors.forename: Kenichiro
authors.initials: K
authors.lastname: Kinouchi
authors.forename: Paolo
authors.initials: P
authors.lastname: Sassone-Corsi
mesh_terms: D063646:Carcinogenesis / Q000235:genetics; D002453:Cell Cycle / Q000502:physiology; D049109:Cell Proliferation / Q000235:genetics / Q000502:physiology; D002471:Cell Transformation, Neoplastic / Q000235:genetics; D057906:Circadian Clocks / Q000502:physiology*; D002940:Circadian Rhythm / Q000502:physiology*; D004734:Energy Metabolism / Q000502:physiology; D044127:Epigenesis, Genetic; D006801:Humans; D009369:Neoplasms / Q000235:genetics / Q000378:metabolism / Q000503:physiopathology