Scientists have pinpointed a cancer protein which controls the disease's spread from the skin to other organs, and proposed on Wednesday that blocking it may be an effective treatment. Working with mice genetically engineered to develop human skin cancers, the team discovered that the protein plays a key role promoting - or inhibiting - metastasis, the spread of cancer from one area or organ to another.
Dubbed MIDKINE, the protein is secreted by melanomas - the most serious type of skin cancer - before travelling to a different part of the mouse body to kickstart cancer formation, they said. In subsequent observations in humans, high levels of MIDKINE in the lymph nodes of skin cancer patients were predictive of "significantly worse" outcomes, the team reported in the science journal Nature.
This was the case even if there were no tumour cells in the lymph nodes. "In MIDKINE we have found a possible strategy that merits consideration for drug development," said Marisol Soengas of the Spanish National Cancer Research Centre in Madrid, a co-author of the study. Early detection is important in melanoma. After it starts spreading, patient prognosis is usually poor.
It was long thought that melanoma prepares the organs it intends to colonise by activating the growth of fluid-transporting lymph vessels - first in and around the primary tumour, then the surrounding lymph nodes, and so on.
However, removing lymph nodes next to a melanoma tumour does not prevent metastases, meaning there is "something missing" in our understanding of the spread mechanism, said the researchers. The new study offers a possible answer. "When these tumours are aggressive, they act at a distance much earlier than previously thought," said the authors. MIDKINE travelled directly to the new cancer site irrespective of lymph vessel formation around the original tumour.