Cell breakthrough in cancer fight

Australian researchers have made a breakthrough in the fight against cancer and are working to find a way to get the body's natural killer cells to eliminate cancerous cells.

Researchers at Melbourne's Peter MacCallum Cancer Centre have discovered a new molecule that a cancer cell can produce on its surface to convince the body's natural killer cells it poses no danger.

The research team, led by Dr Dan Andrews and Professor Mark Smyth from the Cellular Immunology Laboratory at the centre, says the cancer cells fool the body's natural immune defences into ignoring their threat.

Dr Andrews said the discovery would open the door to the development of new treatments to interrupt this deception.

The findings were published overnight in the prestigious scientific journal Nature Immunology.

Dr Andrews says each natural killer cell is part of a roving biological security team, performing sweeping scans by temporarily binding one of its receptors to a corresponding molecule on every cell's surface, like a key into a lock.

"When a cell becomes infected or damaged, it loses these surface molecules; when a natural killer cell cannot find a lock to bind to, it recognises that cell as a threat and destroys it," he says.

Researchers from around the world have been hunting for each lock to correspond to the 10 identified natural killer cell surface keys, but only investigating the MHC-I class of molecule, or classical MHC-I.

The lock Dr Andrews and his team have discovered, called H2-M3, is a non-classical MHC-I molecule.

"Now we have identified the role H2-M3 plays in cancer growth, we can learn more about how it binds to natural killer cell receptors and plan new therapies to specifically target these types of interactions," Dr Andrews said.

"Blocking this exchange could prevent natural killer cells from binding to cancerous cells and accepting them as harmless, instead prompting the natural killer cells to recognise and destroy them efficiently, as they would any other disease, invading virus or bacteria."

Dr Andrews said that understanding how natural killer cells recognise the H2-M3 lock is a huge step forward in the journey toward new immunotherapies for patients.

"Although these are early days, it is very exciting to make discoveries that may very well result in new ways to help a patient's immune system fight cancer," he said.

"Right now, we have one more molecule to work on, and the possibility of many more tomorrow."