Most cells have something like an internal clock. Centrally, this inner Clock is controlled by the brain. A permanent disturbance of the day-night rhythm leads to an imbalance in reading of tumor-promoting and tumor-inhibiting genes, which is seen as the cause of tumor growth.

In order to assess the feasibility of an in vitro approach to studying the effects of disturbances of the circadian rhythm, the scientists, led by Prof Amita Sehgal from the Perelman School of Medince at the University of Pennsylvania, have used a common circadian model. It consists of a human bone cancer cell line in which a luciferase reporter gene has been incorporated. This reporter cell line enables the measurement of cellular rhythms. At regular intervals Dexamethasone was added to the nutrient solution thus simulating jet lag. Dexamethasone is a synthetic glucocorticoid normally used to treat inflammation.  

The scientists were able to observe that the cells showed an increase in cell proliferation dependent on circadian rhythm. Among other things, they produced an increased amount of cyclin D1, a protein that accelerates one step of the cell division process.

The research team now wants to test drugs for their suitability of a cancer-inhibiting effect.

The scientists have published their findings in the journal PLoS Biology:
Yool Lee et al (2019). G1/S cell cycle regulators mediate effects of circadian dysregulation on tumor growth and provide targets for timed anticancer treatment. PLoS Biology. https://journals.plos.org/plosbiology/article?id=10.1371/journal.pbio.3000228

Source:
https://www.wissenschaft-aktuell.de/artikel/Wie_Jetlags_or_Schichtarbeit_das_Krebsrisiko_erhoehen1771015590695.html