Key to metastasis from lung and breast cancer discovered by Spanish scientist Joan Massagué
According to a study on breast cancer led by Joan Massagué, director of the Biology and Genetic Cancer Programme in the Memorial Sloan-Kettering Cancer Centre in New York (MSKCC) and director of the Biomedical Research Institute in Barcelona (IRB), reported in El País today, just a few genes provide the conditions necessary for a malignant cell to form a new tumour in a distant organ, leading to metastasis. The study found that certain genes are responsible for the formation of new capillaries where a malignant cell from a primary tumour can escape from.
The investigative team has identified to date a group of 18 genes which are strongly implicated in the spread of tumours. This latest study by Massagué has discovered that out of all these 18 genes there are 4 which provoke at least 2 circumstances in which the spread of a cancer can take place. On the one hand the formation of new blood vessels around the tumour and on the other hand, the perforation of small capillaries which feed and give oxygen to a certain organ.
The study carried out by Massagué, published today in Nature magazine, looked specifically at the breast and lungs.
This latest research has discovered that 4 proteins acting together cause the formation of new blood vessels around a tumour, as demonstrated in experiments on mice. It is these new vessels which are responsible for giving oxygen and feeding the tumour which in turn favours its growth. However, these vessels are imperfect in that they are porous and it is through these pores that malignant cells can escape into the blood stream. Massagué pointed out that it was already known that for every cubic centimetre of a tumour a million malignant cells could escape, however what was unknown until now was which genes or specific proteins were implicated in this.
It was also known that once cancer cells reach the blood stream they needed to be sufficiently prepared in order to resist attacks by the body’s own natural defence system in order to reach a distant organ. The study by Massagué and his research team explains how a malignant cell can leave the capillaries surrounding the lungs and survive in the blood stream.
Again it is the action of 4 proteins that allow a cancerous cell to leave the cells that form the walls of a tiny capillary. It was discovered that the way that they do this is by almost sliding between the substances that cement the cells of the capillary.
In another study published in the magazine PNAS, Massagué and other scientists from other countries investigate the role that the group of 18 genes play in breast cancer and the way it spreads to the lungs.
Massagué thinks that more than half of the 18 genes could have a relevant role in the spread of this type of cancer.