title: Oscillation of clock and clock controlled genes induced by serum shock in human breast epithelial and breast cancer cells: regulation by melatonin.
abstract: This study investigates differences in expression of clock and clock-controlled genes (CCGs) between human breast epithelial and breast cancer cells and breast tumor xenografts in circadian intact rats and examines if the pineal hormone melatonin influences clock gene and CCG expression. Oscillation of clock gene expression was not observed under standard growth conditions in vitro, however, serum shock (50% horse serum for 2 h) induced oscillation of clock gene and CCG expression in MCF-10A cells, which was repressed or disrupted in MCF-7 cells. Melatonin administration following serum shock differentially suppressed or induced clock gene (Bmal1 and Per2) and CCG expression in MCF10A and MCF-7 cells. These studies demonstrate the lack of rhythmic expression of clock genes and CCGs of cells in vitro and that transplantation of breast cancer cells as xenografts into circadian competent hosts re-establishes a circadian rhythm in the peripheral clock genes of tumor cells.
authors.affiliation: Department of Structural and Cellular Biology, Tulane University School of Medicine, 1430 Tulane Avenue, New Orleans, LA 70112, USA.
authors.forename: S
authors.initials: S
authors.lastname: Xiang
authors.forename: L
authors.initials: L
authors.lastname: Mao
authors.forename: T
authors.initials: T
authors.lastname: Duplessis
authors.forename: L
authors.initials: L
authors.lastname: Yuan
authors.forename: R
authors.initials: R
authors.lastname: Dauchy
authors.forename: E
authors.initials: E
authors.lastname: Dauchy
authors.forename: D E
authors.initials: DE
authors.lastname: Blask
authors.forename: T
authors.initials: T
authors.lastname: Frasch
authors.forename: S M
authors.initials: SM
authors.lastname: Hill