Salmonella to fight cancer

The way Salmonella bacteria infect humans could be exploited to kill cancerous cells say scientists at the University of Glasgow and the University of Massachusetts.

Salmonella uses caspase-3, an enzyme produced by the infected host cell to deliberately increase inflammation at the site of infection. Normally, the enzyme is involved in programmed cells death or apoptosis and removes damaged or malfunctioning cells, but a Salmonella protein called SipA can induce caspase-3 activation within a host cell – a process that could be exploited in cancer where apoptosis is defective.

“The novelty of this research is that we show how the bacteria are undermining the host cell and getting it to process the bacterial toxins into functional units,” said Dr Dónal Wall.

Caspase-3 only cuts specific sequences within proteins known as caspase-3 cleavage sites. These sites are also found in several Salmonella proteins which appear to be involved in bacterial entry or are used to overpower the host cell.

“The bacteria deliver large toxins into the cell and then use the host enzyme, caspase-3, to divide these proteins,” said Wall, “These toxin can then go to different parts of the cell to carry out their individual functions.”

Wall hopes the process could be exploited in cancer therapeutics to activate programmed cell death in cells which are in the early stages of the defective process.