Chemical messengers, which traditionally fight infection and help to heal the body, can turn traitor and cause ovarian cancer to spread, says a study1 published today.
Cancer Research UK scientists have discovered that one of these chemicals, detected in ovarian cancer, actually encourages the growth and spread of ovarian tumours.
A scientific study led by Professor Frances Balkwill at Cancer Research UK’s translational oncology laboratory in London, has identified an individual chemical messenger, known as a chemokine, that increases the ability of ovarian cancer cells to move around the body. Moreover, this chemokine may help the ovarian cancers to grow when they reach other organs.
Chemokines usually fight infections and boost immune responses by attracting healing cells to troubled areas.
They are generally regarded as the “good guys” which work to heal the body. But they can have a dark side when it comes to the spread of cancer.
“If chemokines are made in the right place at the right time in the correct amount for the correct period of time then they are really very useful,” says Prof Balkwill, of Queen Mary’s Medical School, London. “But if they are made in the wrong place at the wrong time and for too long that’s when they cause a problem.
“Chemokines appear to behave in a contradictory way because while their primary function is to move ‘good’ cells around the body to fight infection, they also play a harmful role in encouraging cancer cells to spread.”
Other studies have identified different chemokines in a variety of other cancers. For instance, a different chemokine encourages breast cancer cells to spread to lymph nodes.
This latest discovery is a new piece in the jigsaw puzzle of how ovarian cancer spreads.
The next stage is for scientists to find what will inhibit these unwanted actions of chemokines. There is evidence that some drugs, currently used in the treatment of advanced cases of HIV/AIDS, do stop cells responding to the chemokine.
“We hope that further scientific tests might show that these types of drugs can be useful in the treatment of cancer,” says Prof Balkwill.
Sir Paul Nurse, chief executive of Cancer Research UK, says: “Each new discovery that tells us something about the way tumours behave and how they spread in the body is very important in adding to the bank of information that will ultimately enable us to control the progress of cancer.”
- Cancer Research: 62; pp.5930-8
The human body produces a number of different chemokines that are very important in controlling the movement of cells, especially cells of the immune system, around the body.
Chemokines, for instance, will direct white blood cells from the bone marrow where they are made, to the sites in the body where they will be needed to guard against infection. When immune cells encounter an infection in the body, it is chemokines that guide them to lymph nodes where they can initiate and control the immune response.
The chemokine that is important in ovarian cancer is called CXCL12. It makes cancer cells move by binding to a receptor called CXCR4 that is found on the surface of the cancer cells. Often cells will have a number of chemokine receptors on their surface, but ovarian cancer cells only express CXCR4.