New therapeutic target for some breast cancers discovered
By ANISaturday, October 9, 2010
WASHINGTON - Scientists have discovered a new therapeutic target for some breast cancers.
A protein that pumps calcium out of cells also moonlights as a signal to get massive quantities of the stuff to flow in, according to Johns Hopkins scientists.
Their discovery of this surprisingly opposite function highlights the link between calcium and cancer and holds the promise of a new therapeutic target for certain breast cancers.
The Hopkins study focused on the enigmatic molecular machines known as SPCA2 that are found in very high levels in human breast cancer cells.
Historically, SPCA2 were assumed to be redundant and less essential versions of better-known calcium pumps that scavenge calcium inside of cells everywhere in the body and store it away.
Mingye Feng, a graduate student of physiology in the Johns Hopkins University School of Medicine, learned that wasn’t necessarily the case as he conducted a standard control experiment and put the gene that codes for the SPCA2 pump into an ordinary human cell.
He expected that if the pump were functional, calcium levels in the cell would decrease and if it were not, the levels wouldn’t change much or at all. Instead, the calcium levels rose dramatically.
Experiments showed that SPCA2 actually moves from its normal location inside cells to the cell surface, where it interacts with porelike openings called calcium channels. SPCA2 activated the channels, essentially calling all calcium into the cells.
This newly discovered mechanism may provide an underlying cause for the microcalcifications (deposits of calcium) in breast tissue that, detectable by mammograms, may signal cancer,says Rajini Rao, Ph.D., a professor of physiology in the Johns Hopkins University School of Medicine.
The study has been reported Oct. 1 in Cell. (ANI)
