BRISTOL, England, July 1 (UPI) -- Researchers have found that inflammatory cells sent by the immune system to the site of a wound for healing are redirected to pre-cancerous cells they help grow.
While tissue damage and cancer have been linked before, researchers have now seen inflammatory cells called neutrophils be diverted from wounds to pre-cancerous cells in adult zebrafish.
"There is a longstanding association between wound healing and cancer, with cancer often described as a 'wound that does not heal,'" said Dr. Nicole Antonio, of the School of Biochemistry at Bristol University, in a press release. "Surgery is a key cancer therapy and is still the most effective method to treat human solid cancers that have not yet metastasized. However, tissue damage has been previously linked to cancer development and progression. Therefore it is important that we understand the dynamic molecular mechanisms for this process and uncover how clinicians can minimise the risks for cancer patients."
Researchers started off with zebrafish larvae that had been genetically modified to produce pre-cancerous cells, watching as neutrophils sent by the immune system to heal a wound were diverted away to nearby pre-cancerous cells, helping them grow. This growth is caused by the release of a signaling molecule called prostaglandin-E2, which is released by the immune cells.
The same process was then shown to happen in adult zebrafish models, where repeated wounding led to an increase in melanoma formation.
"Our results provide direct visual evidence of a physical link between wound-associated inflammation and the development of skin cancer," says EMBO Member Paul Martin, professor at Bristol University and the University of Cardiff. "White blood cells, in particular neutrophils, that typically serve as part of the body's built-in immune system are usurped by nearby precancerous skin cells in a way that leads to the proliferation of tumour cells in our zebrafish model experimental system of human melanoma."
The researchers then compared the inflammatory response in human melanoma samples that were either intact or had "ulcerated" open wounds. A strong presence of neutrophils was seen at the sites of melanoma ulceration and cancer cell division, raising researchers' concerns that an inflammatory response to cancer surgery, or even biopsy collection, could cause growth of remaining cancer.
"Surgery plays a vital role in helping thousands of people survive cancer every year," said Dr. Emma Smith, senior science information officer at Cancer Research UK. "This study, mostly in zebrafish, suggests that the immune response caused by wounds may encourage cancer cells to grow, but there's no proof yet that having surgery causes the same thing in patients. If the immune response triggered by surgery is linked to cancer growth, then understanding this relationship could lead to ways of blocking it."
The study is published in The EMBO Journal.