Cancer stem cells in their niche - like embryos in a womb.

Stromae recently gained a lot of attention with his single ‘Quand est?’. In his macabre video he gets killed by cancer as he dances and tries to fight it. Throughout the video the cancer spreads and grasps everything that comes in her way: a true resemblance to what it does in real life. As all of you might have experienced in your daily life is cancer a devastating disease; killing thousands of people on a yearly basis. Cancer is an invasive disease that is hard to treat because of reoccurring cancerous cells; making it harder for doctors to eliminate the cancer cells. Recently, scientists had a breakthrough concerning these hard to eliminate cells. They discovered a sub set of cells among the cancer cells, named the cancer stem cells, and how they are maintained in tumours. If drugs are developed that could tackle these cancer stem cells, curing the disease wouldn’t be as difficult as it is today.

But before we dive into the still partly unknown world of cancer stem cells, we have to understand how normal stem cells in our body work. As we age, the tissues in our body get older. These tissues need to be renewed by healthy, new cells in order to maintain tissue functionality. Stem cells in our body are the chosen cells to do so. Stem cells have the capability to divide –we suspect- an infinite amount of times, creating daughter cells that are young and ready to renew tissues. What characterizes these stem cells is the fact that they also give birth to new stem cells, creating new cells that also can divide an infinite amount of times and thereby can keep renewing tissues.

Cancer stem cells act in a very similar manner. They might just be the most important cells in an entire tumour as they have the ability to renew and add cells to cancerous tissues, much like normal stem cells do in the healthy tissues of our body. More specifically, these cancer stem cells have the ability to renew continuously; making uncontrollable cell growth possible. In healthy situations, our body has internal mechanisms to stop the dividing of cells when our tissues are healthy and renewed sufficiently. In cancer, this mechanism is either not effective enough to result in a stop or it is inactive due to the errors in the DNA, that is, the information encoded within our DNA is altered in such a way that our control mechanisms are shut down.

What makes cancer stem cells incredibly hard to eliminate is the fact that they are surrounded by what is called a niche. The niche is an all surrounding safe harbour for cancer stem cells where they acquire nutrition and are protected against destructive influences from the external milieu; e.g. chemotherapy and radiation. The niche is for cancer stem cells what the womb is to an embryo: growth is stimulated by nutrition and protection is guaranteed.

This niche is particularly hard to target, mainly because it is still unknown which mechanisms are specifically responsible for the protection and nutrition of the cancer stem cells. Recently it was also discovered that niches could initiate other niches elsewhere in the body. For instance, a cancer stem cell niche in the liver can initiate a niche in the small intestine, thereby accommodating traveling cancer cells by giving them a new place full of nutrition to stay. This highly increases the chance of metastasis (spreading) of the cancer, worsening the patient’s prospect. Metastases are difficult to treat because the cancer cells are ‘on the loose’: they broke out of their original habitat and travelled through the body to reach another location. Hundreds of loose cells are hard to track down and target, resulting in loose cancerous cells throughout the entire body that could possibly initiate tumours elsewhere.

In conclusion, cancer stem cells and their surrounding niche are the initiating and maintaining force behind cancer. Developing medicine that targets the cancer stem cells and their niche, could drastically improve cancer treatment. Attacking the initiating cells could minimize tumour formation and depleting the maintaining forces (e.g. nutrition from the niche) could minimize further spreading of cancer. In this way many patients could have better prospects and lead a much less painful life. Let us all hope that researchers find answers to these problematic factors in cancer and that Stromae creates a new hit in ten years about a better, “cancerless” life.  

- Amy Kessler, 07/10/2015