We are all aware of how dangerous cancer can be, especially when concentrated in the brain, which is responsible for most bodily functions. But how do cancerous cells manage to proliferate so quickly and have enough resources to do so?
There are of course different types of tumors, and their correct classification is necessary for good patient outcomes. Unfortunately, not all cancers are easily treatable, so let’s discuss the most aggressive type of malignant brain tumor - glioblastoma. They fall into the 4th category of gliomas, where the higher the grade is, the more aggressive the cancer can get. These tumors are the number one cause of brain cancer in adults and the elderly. They derive from astrocytes, a type of glial (“helper”) cell in the brain, and they are known to spread rapidly and into multiple areas of the brain, commonly also infiltrating surrounding brain tissue.
Scientists hypothesized that it’s possible glioblastoma can spread so effectively because it tunes in on our body clock - the circadian rhythm. And they were actually correct! It was found that glucocorticoids (when used in treatment outside of our normal hormone production) can, depending on the time of day and the activity of clock genes (Bmal1 and Cry), both either promote or suppress the tumor growth through the glucocorticoid receptor signaling. Blocking circadian signals then results in dramatic slowing of glioblastoma growth and disease progression.
Basically, this tumor functions on the same rhythm as one of the hormones that can possibly be used in treatment. It’s also suggested this hormone can both help and cause trouble because of that, but it is very dependent on timing, the same goes for the rest of the treatment. There have been different outcomes with different timings of treatments, but there are of course more variables that could play a role.
So just remember that when in our lives someone can take advantage, it can happen similarly in our body as well, and the circadian rhythm was the target in this particular situation. That brings the question of what other mechanisms can be exploited similarly by other types of cancer, or other diseases altogether. Maybe we will find out in the future…
Resources:
Gonzalez-Aponte, M. F., Damato, A. R., Simon, T., Aripova, N., Darby, F., Jeon, M. S., Luo, J., Rubin, J. B., Herzog, E. D. (2024) Daily glucocorticoids promote glioblastoma growth and circadian synchrony to the host.
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