as an office worker, many people have such a feeling, now life pressure is increasing, the rhythm is getting faster and faster, once busy as a gyroscope, stop and stop No, no. To make matters worse, many people still have to work night shifts. For Americans, the proportion of night shift workers has reached 15%. Many studies have found that night shift increases the risk of cancer, but the reason is always a mystery.
but recently a good news was sent, and scientists at the Massachusetts Institute of Technology (MIT) may have found a link between the night shift and the risk of cancer, and their research was published on the Cell Metabolism. (Circadian Rhythm Disruption Promotes Lung Tumorigenesis. Cell Metabolism, DOI: 10.1016/j.cmet.2016.07.001)
picture source: TV Drama Night doctor / > Light controlled circadian clocks can control physiological activities such as metabolism or cell division. The MIT team, through experiments on mice, found two miraculous genes that not only control the circadian rhythm of the cells, but also inhibit the tumor.
light controlled biological clock has important functions. Image sources: National Cancer Institute, Christine Daniloff/MIT
if there is a lack of these tumor inhibitors, such as gene knockout or normal daytime / night rhythm, the tumor may be out of control and grow uncontrollably.
Thales Papagiannakopoulos, the first author of this article, who worked at the Koch Institute for cancer research at the Massachusetts Institute of Technology, said, "no matter what means you use, once the biological clock is broken, the outcome is likely to lead to tumor growth."
break the biological clock
for humans, the core biological clock is located in the brain's suprachiasmatic nucleus (SCN), with the aid of the retina, here to receive information about the level of light. Next, through hormones and other signaling molecules, SCN transmits information to somatic cells.
in cells, a gene called Bmal1 is responsible for opening other genes that control circadian activity, including the so-called Per2 gene. In general, the protein levels encoded by these genes are fluctuating, however, once the normal light / dark cycle is broken, the fluctuation will disappear.
"cells need light as a clue, just like some restoration key. Once this clue is lost, the cells in the human body lose normal rhythm. Papagiannakopoulos is now an assistant professor of pathology at New York University School of medicine.
Papagiannakopoulos and colleagues began to study the possible relationship between cancer and these genes, and the subjects they chose were mice with non small cell lung cancer (say the mice were also mouldy because the researchers used genetic engineering to get them to get cancer).
the researchers divided the rats into two groups, corresponding to two different light / dark timetables. One group had a normal schedule: 12 hours of light and 12 hours in darkness. The other group's schedule is rather weird, which can be termed "time difference group": every two or three days, they will receive an additional 8 hours of illumination. The latter mimics the night shift or the jet lag. Compared with the control group,
tumors in the "jet lag" group grew faster and deteriorated more easily.
researchers then did an experiment that made the mice in a normal light / dark environment, but knocked out the Bmal1 gene and the Per2 gene. In this case, the tumor of these mice also grows very fast, just like an abnormal light / dark rhythm.
"if you destroy these genes in the body, even if you receive the normal light / dark information, it is also white, and the normal biological clock will be broken."