Breast cancer invades other organs in the final stage of the disease. Scientists have shown that circulating tumor cells are more aggressive at night, while patients sleep.
breast cancer most often manifests as a small, abnormal lump that, as the disease progresses, grows larger and eventually spreads to other organs. We then speak of breast cancer metastatic. If the tumor continues to progress, duration average life of women with metastatic breast cancer is two to three years.
To metastasize, the primary tumor produces tumor cells that join the bloodstream. These are the circulating tumor cells. They can then establish themselves anywhere in the body, which makes their detection difficult, but in the specific context of breast cancer, they are the bones, lungsthe liver and the brain who are most often affected.
The mechanisms that lead the primary tumor to produce metastases remain largely obscure. Some scientists believe they are produced continuously or as a result of damage physical or mental. Swiss researchers from the universities of Basel and Zurich have obtained surprising results that call into question this postulate. Their work has appeared in Nature a few days ago.
More aggressive tumor cells at night
Indeed, their research conducted on mice or people with breast cancer shows that circulating tumor cells undergo a “boost” of activity during sleep. They are more apt to form metastases than those produced during the day. This observation was made possible thanks to the analysis of RNA expressed by each circulating tumor cell.
RNAs – molecules intermediate between DNA and protein – are the reflection of the activity at a time T of a cell. Thus, during the night the circulating tumor cells very strongly express their Genoa mitotics that allow them to divide. This intense mitotic activity was exclusively observed during the night and is at the origin of the significant metastatic capacity of the circulating tumor cells created at night.
What is going on in our body at bedtime to have such an effect on circulating tumor cells? Researchers believe that the hormone have their say in this story. Melatonin, the sleep hormone, but also the testosterone and glucocorticoids, circulating hormones in the blood that act, among other things, on carbohydrate metabolism, dictate the production dynamics of circulating tumor cells. In conclusion, the production of circulating tumor cells with high metastatic potential is not continuous, but is only concentrated at night.
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