Tumour prompts the immune system to betray us: here is the protein that can stop it

Migration and Invasion Inhibitory Protein identified that can prevent the tumour from 'reprogramming' our defences and becoming more invasive

by Maria Rita Montebelli

20 March 2026

Researcher working with microplate panel for diseases diagnosis in the laboratory. Doctor working with microplate for elisa analysis angellodeco - stock.adobe.com

3' min read

Translated by AI

Versione italiana

3' min read

Translated by AI

Versione italiana

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.

The outcome of the experimental models

And this is not just theory. In experimental models, increasing MIIP means less tumour volume, fewer metastases and a less favourable immune environment for cancer development. And one small detail has raised the researchers' antennae: by intervening in one of the key steps of this circuit, the STING signal, it is even possible to reverse the process. Translated into practice, this means that, at least in theory, it would be possible to turn a tumour 'invisible' to the immune system into a clear and therefore attackable target.

It is this passage (and the great hope) that makes this discovery so much more than good laboratory news. Today, one of the great challenges in oncology is precisely this: many colon tumours do not respond to immunotherapy, which has revolutionised the natural history and prognosis of other tumour types. And this is because many of these tumours are 'cold' (unable to activate an effective anti-tumour immune response) and therefore unresponsive to immunotherapy. Understanding how to 'warm' them up is one of the keys to the future of treatment.

New therapeutic perspectives

And MIIP could be a valuable tool in this regard. Not only as an 'enhancer' of immunotherapy, but also as a biomarker to understand which patients are more likely to respond to certain therapies. Which means, fewer empty treatment attempts and more tailored and effective therapies.

In short, this discovery opens up new possibilities for precision immunotherapy of colorectal cancer, but also opens up broader perspectives. It is also a conceptual revolution: it is no longer just a question of destroying the tumour, but of rewriting the rules of the environment in which it develops (the tumour microenvironment) and remodelling the behaviour of the immune cells.

MIIP could in fact deprive cancer of its internal accomplices, the 'hacked' immune system cells. Because in this case the problem is not only the enemy, but also and above all those who are helping it, without even knowing it.