A DRUG that blocks a human enzyme hijacked by many bacteria and viruses could improve treatments for a range of diseases, including sepsis, anthrax and Ebola. It might even form part of a novel anti-cancer therapy.
鈥淟et me put it this way,鈥� says Iris Lindberg of Louisiana State University. 鈥淚f I thought I had anthrax or Ebola I would take this drug straight away.鈥�
Furin, a protein-cutting enzyme, is found on the surface of most human cells and activates many proteins. Some bacteria exploit it to slice up precursor molecules to produce deadly toxins. Lindberg鈥檚 team reasoned that blocking furin would also block the toxins. So Angus Cameron, now based in Britain at the University of Bristol, created a compound called D6R (hexa-d-arginine) that could do the job.
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When mice were injected with D6R and the toxin from Pseudomonas aeruginosa, which causes sepsis and is a major problem in hospitals, half survived. Those given the toxin alone died, showing that D6R protects against the toxin, the team reports in Infection and Immunity. No side effects were observed, although shutting off furin activity for several weeks would cause serious problems, Cameron thinks.
If proved safe, D6R could be given with regular antibiotics. And because it targets a human enzyme, bacteria are unlikely to develop resistance. 鈥淢icrobes could conceivably evolve so that they use another enzyme to do their protein cleaving, but that is a huge leap,鈥� says Cameron.
The drug could also be effective against viruses, such as Ebola, that use furin to cleave their coat proteins when they replicate. It is already known that small mutations that affect the way viral coat proteins are cut by furin can turn a deadly virus into a largely harmless one.
鈥淚t could also be important in cancer treatment,鈥� says Neil Taylor, a furin expert at the Catholic University of Leuven in Belgium. 鈥淚t鈥檚 well known that over-expression of furin can turn a benign tumour into a malignant one.鈥�