Pro-inflammatory M1 macrophages involved in immune responses accelerate the progression of melanoma through the extracellular vesicles they secrete, a recent study from the University of Eastern Finland shows. The findings were published in Cell Communication and Signaling.
The study, conducted in the Institute of Biomedicine at the University of Eastern Finland, and supported by iCANDoc, Cancer Foundation Finland, the North Savo Cancer Association, the Finnish Cultural Foundation, Paavo Koistinen Foundation, Orion Research Foundation, and the Kuopio University Foundation, explored the molecular mechanisms by which extracellular vesicles secreted by pro-inflammatory M1 macrophages affect melanoma cells. Extracellular vesicles are small membrane-bound particles secreted by cells and used for intercellular communication. All cells secrete extracellular vesicles; however, they seem to play a particularly important role in intercellular communication in the tumor microenvironment.
Macrophages are white blood cells that migrate into the tumour microenvironment in many cancers. A high macrophage count has been associated with a poor prognosis, including in melanoma.
The new study demonstrated that extracellular vesicles secreted by M1 macrophages contain inflammatory mediators such as TNFα and IL-1β, and that these signalling molecules are delivered to cancer cells via extracellular vesicles. The study also showed that extracellular vesicles secreted by M1 macrophages activate the NF-κB signalling pathway in target cells, which plays a central role in inflammation. The resulting inflammatory environment increases the aggressiveness and invasiveness of cancer cells, i.e., their ability to penetrate into surrounding tissue.
Tumour cells and macrophages in their microenvironment are in constant interaction with one another. Understanding these interaction mechanisms is essential for identifying new targets for cancer therapy.
“We showed that extracellular vesicles secreted by M1 macrophages can enhance melanoma cell motility and, as a result, melanoma progression. They enhance inflammatory signals within the tumour microenvironment and create a favourable, self-sustaining inflammatory cycle for cancer cells to thrive in,” explained Doctoral Researcher Kaisa Mäki-Mantila of the University of Eastern Finland.
The findings reveal a key mechanism by which macrophages and cancer cells communicate. This opens up new avenues for discovering methods that could break the inflammatory cycle that fuels tumour growth.
Reference
[1] Mäki-Mantila K, Niskanen EA, Kainulainen K, Pardas LP, Aaltonen N, Wahbi W, Takabe P, Rönkä A, Rilla K, Pasonen-Seppänen S. Extracellular vesicles derived from pro-inflammatory M1 macrophages induce an inflammatory and invasive phenotype in melanoma cells. Cell Commun Signal. 2025 Dec 3;24(1):10. doi: 10.1186/s12964-025-02571-8. PMID: 41339851; PMCID: PMC12781609.[Download the full article]
Featured image: Melanoma cells with the cell membrane protein CD44 stained in red and the nucleus in blue. Dil-labelled extracellular vesicles taken up by cancer cells are shown in green. Image courtesy © 2026 Kaisa Mäki-Mantila. Used with permission.
