Research shows that breast cancer cells are more likely to enter the blood when patients sleep

When tumor cells in the body enter the blood and move to new sites “ Take root and sprout ” when , The fatal risk of cancer is also the highest , This process is called transfer （metastasis）. A new study finds , For breast cancer patients , These are called circulating tumor cells （circulating tumour cell,CTC） Of “ rogue ” Cells enter the blood more easily at night than during the day .

 

Figure 1 : Metastatic cancer cells will move from one location in the body to another , Form new tumors . source ：Science Photo Library

This discovery reveals some basic physiological characteristics of the human body that have not been noticed before , Better monitoring of cancer progression is expected , Time biologist at the University of Manchester, UK Qing-Jun Meng say .

How does the circadian rhythm of the body affect the development of cancer , This is a problem that the scientific research community has explored for decades . With this research , We can now be sure “ The tumor will wake up when the patient sleeps ”, Co author of the paper 、 Cancer biologist at the Federal Institute of technology in Zurich Nicola Aceto say , This is a progress in the study of tumor metastasis .“ In the long run , Any progress is good for patients .” The study 6 month 22 Published on 《 natural 》[1].

Cancer clock

2007 year , The international agency for research on cancer lists the disordered circadian rhythm as a “ Probably ” Carcinogen , Previous long-term research found , People who work irregular hours have a higher risk of breast cancer , Such as flight attendants and night nurses [2]. The reason for this phenomenon has not been decided .

In one day 24 In the hours , A person's circadian clock is controlled by different genes that express specific molecules . Circadian biological clock will affect various physiological processes in the body , Including metabolism and sleep . However ,Aceto say , Most researchers thought it was messy at first 、 Highly variable cancer cells do not have this rhythm .

For tumor metastasis , The first hint that the above view may not be completely correct , Appear when Aceto And colleagues noticed Tumor mice CTC The level will change with the time of blood drawing . This discovery made Aceto Decide to collect at two time points 30 Blood samples from female hospitalized patients with breast cancer , Once in the early morning 4 spot , Once in the morning 10 spot .

The team found , Most of what they detected in blood samples CTC—— Almost account for 80%—— All appear in the early morning 4 Among the samples collected at point , That is, when the patient is still sleeping .Aceto say , In limine “ I was surprised , Because classic textbooks say , Tumors release circulating cells all the time . But our data is beyond doubt . therefore , After a short surprise , We began to feel excited .”

Next , The team wants to verify whether this phenomenon can be extrapolated to these few patients . So , The team first transplanted breast cancer tumors into mice , These mice were monitored for CTC level . The circadian rhythm of mice is opposite to that of humans —— They are most active at night , During the day, rest is the main . The team found , The of these mice CTC The level peaked during the day , That is, when the mouse is still sleeping , Sometimes CTC The content can reach the baseline level 88 times .

Besides , The research team was still sleeping and active in mice , For their bodies CTC Samples were taken . They labeled the two groups of cells with different fluorescence , Then inject these cells back into the mice . Most of the cells that grow into new tumors are collected when the mice sleep , Prompt these CTC Have stronger transfer ability for some reason .

This discovery “ Shocking ”, Cancer biologist at the Ludwig Cancer Institute in New York City Chi Van Dang say . The doctor will measure the blood CTC level —— As a kind of liquid biopsy to help judge the cancer progress of patients , therefore “ My first reaction was , Blood taken at different times of the day may give misleading information ,” He said , This means that doctors may need to think twice when monitoring cancer progression .

Don't treat sleep as an enemy

Aceto say , Why human breast cancer cells are more active at night , This may depend on many factors that remain to be studied . Hormones are the body that tells us when to get up 、 A signal of when to go to bed , It may have played a role . The team found , Using testosterone or insulin on mice will affect CTC level —— Make it lower or higher , It depends on the time of hormone use .

Understand the mechanism behind this phenomenon , It is expected to find better cancer therapies in the future ,Dang say , But this day may have to wait a long time . He said , More research is urgently needed , To clarify the complex relationship between circadian rhythm and cancer .

meanwhile ,Meng Also remind Sleep should not be regarded as the enemy of patients with breast cancer . Studies have shown that , Sleep time every night is long-term insufficient 7 Hours of cancer patients , The risk of death is also higher [3]; Disrupting the circadian rhythm of mice will also speed up cancer metastasis [4]. The results of this study are not saying “ Don't sleep or sleep less ”, He explained. ,“ The results only show that these cells prefer one day 24 Enter the blood at a specific time in the hour .”

reference ：

1. Diamantopoulou, Z. et al. Nature https://doi.org/10.1038/s41586-022-04875-y (2022).

2. Erren, T. C. et al. Dtsch. Arztebl. Int. 107, 657–662 (2010).

3. Cappuccio, F. P. et al. Sleep 33, 585-92 (2010).

4. Lawther, A. J. et al. Brain Behav. Immun. Health 21, 100428 (2022).