Washington: Scientists have identified a molecule in immune cells that inhibits melanoma growth in mice, a landmark finding which they say could shape the future treatment of the dangerous skin cancer.
Researchers from Brigham and Women`s Hospital (BWH) in Boston, the US, found that high expression of a cell-signaling molecule, known as interleukin-9, in immune cells inhibits melanoma growth.
After observing mice without the genes, responsible for development of an immune cell called T helper cell 17 (TH17), the researchers found that the mice had significant resistance to melanoma tumor growth, suggesting that blockade of the TH17 cell pathway favoured tumour inhibition.
The scientists, who detailed their finding in the journal Nature Medicine, also noticed that the mice expressed high amounts of interleukin-9.
"These were unexpected results, which led us to examine a possible contribution of interleukin-9 to cancer growth suppression." said study co-author Rahel Purwar, a PhD scholar at BWH`s Department of Dermatology.
The team next treated melanoma-bearing mice with T helper cell 9 (TH9), an immune cell that produces interleukin-9. They saw that these mice also had a profound resistance to melanoma growth. This is the first reported finding showing an anti-tumour effect of TH9 cells, the researchers said.
Moreover, they were able to detect TH9 cells in both normal human blood and skin, specifically in skin-resident memory T cells and memory T cells in peripheral blood mononuclear cells.
In contrast, TH9 cells were either absent or present at very low levels in human melanoma. This new finding paves the way for future studies to assess the role of interleukin-9 and TH9 cells in human cancer therapy, they said.
"Immunotherapy of cancer is coming of age, and there have been exciting recent results in patients with melanoma treated with drugs that stimulate the immune system," said lead author Thomas Kupper, chair of the BWH Department of Dermatology.
"We hope that our results will also translate to the treatment of melanoma patients, but much work still needs to be done," Kupper said.
Other cell-signalling molecules have been used in treating melanoma; however, this study is the first to investigate the role of interleukin-9 in melanoma tumour immunity, he added.
Melanoma is the most dangerous form of skin cancer, which kills about 9,000 people a year in the US alone. It is curable if recognised and treated early.