ANTHRAX AND CANCER

[Guest guest]

Anthrax to fight cancer?

Anthrax can be disabled and turned into a cancer-fighting weapon that shows

real promise against some types of the disease, scientists have announced

Researchers led by Shihui Liu and Hannah son at the US National

Institutes of Health in Bethesda, land, said the anthrax bacteria -- often

considered a biological weapon -- can be turned from a military killer into a

potential cure. Their paper is published in the journal Proceedings of the

National

Academy of Science.

In it, the authors describe how a modified form of anthrax, injected into

mice, killed three types of tumours with no apparent toxic effects on other

tissue. After only one treatment, the toxin reduced the size of tumours in the

mice

by between 65 and 92 per cent. Two treatments completely abolished 88 per

cent of fibrosarcomas, or malignant tumours, and 17 per cent of melanomas (skin

and peripheral organ tumours). The anthrax was so lethal, tumour cells began

dying just 12 hours after treatment first began. Normally, the toxin produced by

a bacterium, Bacillus anthracis, is activated when it comes into contact with

furin, an enzyme found in all living cells. To render it safe, the scientists

genetically engineered the furin activation sequence out of the toxin, and

replaced it with an artificial peptide sequence that is activated by urokinase.

This is a protein found in very high levels in human tumour cells, making it

an ideal target for cancer treatment. Based on the results so far, researchers

say that melanoma, colon and breast tumours would be the most susceptible

cancers to the anthrax toxin. The team found that the toxin did not damage skin

cells or hair follicles surrounding the tumour, suggesting the treatment may not

have the same severe side effects as current cancer therap given the potent

toxic effects of anthrax, it will be several years before any treatment

involving the toxin is likely for human trials. Professor Kefford, a

cancer

specialist with Sydney's Westmead Hospital, was interested in the results but

not overly excited, saying it's far easier to cure cancer in mice than humans.

" We've seen it many times with different treatments -- curing cancer in mice

is a snap, but regrettably, when you get into humans, it's a lot more

complicated. " Kefford said other anti-cancer agents had proved problematic, such

as the

Onyx virus which targets cells with a mutation in the p53 gene, a gene

commonly found in cancer cells. " There are lots of problems and the treatment

can

have all sorts of unforeseen side effects on non-specific targets [such as other

tissues], " he said. " But having said this, it's still a very interesting new

aspect of a potential therapeutic agent. " Courtesy: ABC Science

OnlinePublished on 27th J