Could a Cellular Doorway for Iron Help Deliver Cancer Drugs?
By LIDA TUNESI
Sometimes called the “iron door”, the protein CD71 lives in the membrane of human cells. It’s not made of iron — rather, CD71 acts as a doorway for iron to enter cells. The protein is a receptor for the biomolecules that ferry iron around the body.
Ferritin is one such biomolecule. Scientists think they can exploit the relationship between ferritin and the “iron door” for a new form of cancer treatment and to fight certain pathogens, but until now the interaction between the two was not well understood.
Professor Amédée des Georges of The City College of New York and The Advanced Science Research Center at The Graduate Center, CUNY, along with colleagues in Italy, determined the structure of the ferritin-CD71 complex using a Nobel Prize-winning method that provides ultra-high resolution. Their work appears in Nature Communications.
Some of the most common types of cancer cells have extra “iron door” receptors. This, coupled with the fact that ferritin can carry small molecules, could make ferritin and CD71 a good cancer-fighting team. The idea is to use ferritin, or a polymer chain of ferritins, to relay a radioactive tracer or a drug right to the afflicted cell.
A better understanding of how ferritin and CD71 interact could let researchers engineer ferritins that bind even more strongly to the receptor and better target cancer cells.
Certain pathogens such as the malaria parasite and human arenaviruses mimic the way ferritin complexes with CD71 to gain access to cells, like using a disguise to get past a guard. Knowing how that complex works could help scientists find ways to block those pathogens from getting in.
The study also helps clarify how our cells are supplied with this important element.
“More fundamentally,” said des Georges, “this structure allows us to better understand the process of iron entry into the cell: how it is mediated by different processes and different transporters, but all using the same receptor — the ‘iron door.’”