Fig. 7

Model for the suppressive effect of clock activation on tumor growth. Untreated cancer cells harbor an inactive circadian clock and exhibit fast cell cycle progression and fast tumor growth (left). Dexamethasone (DEX), Forskolin (FSK), serum shock or heat shock activate the circadian clock in cancer cells, which regulates circadian expression of cell cycle checkpoint genes (in particular factors regulating G1-to-S transition), which results in slower tumor growth (right). Treatment of cancer cells transfected with Bmal1 shRNA does not result in an activation of the circadian clock and thus no rhythmic cell cycle gene expression, which results in fast tumor growth (left). See Discussion for details