Health - Researchers find trigger for killer protein (V.G.Read)

CHICAGO (Reuters) - U.S. researchers have found a way to switch on a cell-killing protein in the body, a finding that could lead to new ways to treat diseases like cancer in which cells grow out of control.

The body naturally activates this protein, called BAX, to kill off unwanted or defective cells in a process of programed cell suicide called apoptosis.

Researchers at Harvard's Dana-Farber Cancer Institute now think they have found a way to trigger this process.

"We identified a switch that turns BAX on, and we believe this discovery can be used to develop drugs that turn on or turn off cell death in human disease," said Dana-Farber's Dr. Loren Walensky, who reported his findings on Wednesday in the journal Nature.

Walensky said his team was able to activate this switch by making a carefully shaped peptide -- a small chain of amino acids -- that fit perfectly into the trigger mechanism.

When this peptide attached correctly, the BAX protein started killing off cells by poking holes in the membranes of mitochondria, which make energy in cells.

Walensky, who is co-founder of Aileron Therapeutics, a biotech company in Cambridge, Massachusetts, thinks this mechanism may be useful in drug development.

"Because BAX lies at the crossroads of the cell's decision to live or die, drugs that directly activate BAX could kill diseased cells like in cancer and BAX-blocking drugs could potentially prevent unwanted cell death, such as in heart attack, stroke, and neurodegeneration," Walensky said in a statement.

Aileron is testing a cancer drug that targets this trigger and hopes to begin human trials within a year.

(Reporting by Julie Steenhuysen; Editing by Maggie Fox and Jackie Frank