Colon cancer is not just a matter of crazy cells growing out of control. It is, increasingly, a story of bad relationships. And of dangerous alliances. That between the tumour itself and our immune system which, instead of defending us, ends up lending a hand to the enemy. And it is precisely in the context of this ambiguous game that comes a discovery capable of interrupting this ‘hijacking’ and, in the long run, also of leading to new treatments.
A group of Chinese researchers (first name Shuai Chen of the Institute of Oncology at Tianjin University) has identified a protein, MIIP (Migration and Invasion Inhibitory Protein), which could play a decisive role: it acts as a hidden brake, capable of preventing the tumour from ‘reprogramming’ our defences and directing them against it. When this brake works, the immune system stays on the right side and fights the tumour. When, on the other hand, it is blocked, the tumour takes control and becomes more and more invasive.
The biology of tumours
To understand why MIIP is so important, we need to look at one of the most fascinating and disturbing mechanisms in cancer biology. Macrophages are the cells of the immune system that should always be on the front line against threats. But in the presence of a tumour they are sometimes ‘persuaded’ to switch sides and become accomplices of the enemy. In their ‘M2’ version, instead of attacking, they ‘protect’ the tumour cells, promote their growth and, above all, their spread to other organs, practically preparing the ground for metastasis, which is the real cause of cancer mortality in most cases.
And this is where the MIIP protein comes in. The study published in Cancer Biology & Medicine shows that this protein is able to block the signal that turns macrophages into tumour allies. It is as if it prevents the cancer from ‘talking’ to the immune system and, in so doing, manipulating it. When MIIP is present in adequate quantities, this toxic dialogue is interrupted and the tumour loses one of its main allies: an immune system ‘corrupted’ in its favour.
In contrast, when the MIIP protein is missing or scarce, a complex chain of signals (STING-NFκB2-IL10 axis) is activated that completely reverses the situation. Tumour cells start producing substances that ‘numb’ the immune response and turn macrophages into powerful allies of the disease. Hence, a vicious circle is triggered: the more the tumour grows, the more it strengthens its self-protection system, thus becoming increasingly difficult to target.
