Inflammation might be known as the body's natural defense mechanism. But it is also linked to cancer progression for long. The actual process by which inflammation triggers cancer has been uncovered by scientists with A*STAR's Singapore Immunology Network (SIgN) .
They have shown for the first time that a certain type of immune cell can accelerate the growth and spread of cancerous tumours directly.
Using a mouse model of melanoma, one of the most aggressive types of skin cancer, Benjamin Toh, an A*STAR scholar working under the supervision of Professor Jean-Pierre Abastado, a Principal Investigator of SIgN, discovered that the primary tumour first produces a unique protein "CXCL5".
That in turn attracts the PMN-MDSC immune cells to the primary tumour, accelerating its growth. These PMN-MDSC immune cells also reactivate an innate cellular programme in early skin growth, which causes the cancer cells to detach and spread from the primary tumour to other parts of the body. However, this migratory ability is transient; migrating cancer cells can spontaneously lose their migratory potential and form a new tumour in another site.
Said Prof Abastado, "We are really excited because our finding is a clear mechanistic explanation for the long-recognized link between inflammation and cancer progression. It may have significant and far-reaching clinical implications in the way we treat cancer. This study will certainly prompt us to re-think about cancer therapies that aim at boosting the immune system."
This latest finding on the cancer cells' transient migratory ability also reinforced the team's earlier studies which showed that cancer cells can in fact detach and migrate away from the primary tumour at a very early stage, often before the primary tumour is even detected. This challenges the current theory that cancer progression is a linear process, where the developing cancer cell sequentially accumulates mutations that give it the ability to metastasize i.e. to migrate from the primary tumour and settle in a new site to establish a new tumour.
Prof Paola Castagnoli, Scientific Director of SIgN added, "This study has definitely opened a new area in cancer research where more specific therapeutic targets might be uncovered within our body's immune system. It is such new knowledge discovered through fundamental research that we are able to find new strategies to combat complex clinical conditions like cancer with a more holistic and effective approach."
The research findings are published in PLoS Biology.