Discovery of Protein Structure May Help Fight Cancer, HIV

Scientists have discovered the structure of a receptor protein known to play roles in cancer growth and HIV infection. The finding paves the way for understanding how the receptor, nicknamed CXCR4, works, and finding a way to control its activity, the researchers said.

"No one knew what the structure of the receptor looked like," which is a key step in finding a way to stop its action, said study researcher Raymond C. Stevens of the Scripps Research Institute in California.

Stevens and other scientists spent three years using an imaging technique called X-ray crystallography, and found CXCR4's molecules form pairs. The pairs are what allow the receptor to receive signals from outside the cell.

"By knowing what the CXCR4 receptor looks like, one can block its binding site," Stevens told MyHealthNewsDaily. This would be similar to filling a keyhole with glue to disable a lock, he said.

CXCR4 is part of a family of proteins that transmit outside signals to the inside of cells. Many drugs already target this group of proteins because they control fundamental processes such as cell growth and hormone production.

Researchers have long known CXCR4 activates the immune system and spurs cell movement. It can enable cancer cells to grow and spread, when other cell signals aren't working properly, and it helps HIV infect white blood cells by allowing the virus to bind and enter into cells.

The imaging technique revealed that the protein is shaped like two wine glasses that touch in a toast, and has inhibitors for signaling at its sides, Stevens said.

Now, drug researchers need to find a way to manipulate CXCR4 in order to hamper its ability to spur cancer growth and HIV infection, Stevens said.

The findings were published online today (Oct. 7) in the journal Science.