New technique may lead to early liver cancer diagnosis

Exposure to a fungal toxin - a potent carcinogen - may cause up to 80 per cent of liver cancer around the world, say MIT scientists who have developed a new way to detect early signs of the deadly disease.
Researchers from Massachusetts Institute of Technology (MIT) in the US exposed mice to a single dose of aflatoxin, four days after birth. After this exposure, all of the mice eventually developed liver cancer.
They then sequenced DNA from those tumours and also from liver cells removed only 10 weeks after exposure, before tumours developed.
To find mutations at about 10 weeks, the researchers used a powerful genome sequencing technique that combines data from two complementary strands of DNA.

"What we are doing is creating a fingerprint," said John Essigmann, of MIT.
"It is really a measure of prior exposure to something that causes cancer," he added.

Researchers found that at 10 weeks, a distinctive pattern of mutations that can serve as a 'fingerprint' for aflatoxin exposure had already emerged.
Specifically, about 25 per cent of the mutations occurred in CGC sequences. For reasons not yet known, aflatoxin is much more likely to produce mutations in guanine when it is flanked by cytosine on both sides, researchers said.
This fungus is often found in corn, peanuts, and other crops that are dietary staples in Southeast Asia and sub-Saharan Africa regions.

The study was published in the journal Proceedings of the National Academy of Sciences.