Cytogenix (fka CYGX)

[Tatonkano62]

Hey, I'm all for giving Chen the 18 million shares. But the clowns haven't done anything with his technology. This article is from 2001.


Assembly line

13:28 09 January 2001
From New Scientist Print Edition. Subscribe and get 4 free issues.
Philip Cohen, Snowbird


A new technology that allows mammalian cells to produce tiny strands of biochemically active DNA may open the door to new types of gene therapy.

Yin Chen of CytoGenix, a biotech company in Houston, Texas, and his colleagues have already shown they can use the technique in the test tube to produce DNA enzymes and drive cancer cells to self-destruct.

"This is pretty nice and there is so much they could do with this," says Gerald Joyce of the Scripps Research Institute, a pioneer in the design of DNA enzymes.

Joyce points out that small pieces of DNA produced by the technique could alter cell biology in many other ways. They can simply bind to RNA, grab other complex molecules or squeeze into an existing DNA double helix. Chen says his group has ongoing collaborations to look at these different applications.

DNA in action
In its natural role in the cell, DNA only stores information. Before its genetic data is put to use, the DNA must be copied into RNA, which is shuttled to cellular factories to make proteins. Proteins, in turn, provide the biochemical muscle that drives the biology of the cell.

Yet biologists have been able to design small, single-stranded DNA enzymes that have the chemical capability to slice RNA. For years, medicinal chemists have been investigating the use of these talented enzymes as drugs.

For chronic diseases, a continual dose of this complex medicine would be required, so it would be better to get cells to produce DNA enzymes themselves. But no-one had figured out how to persuade cells to make such unnatural molecules.

Complex strategy
Chen's team pulled off this feat by combining a number of known genetic tricks into a complex production scheme, worthy of Heath Robinson or Rube Goldberg. They used the gene for a 40 letter DNA enzyme that chops the RNA of a cancer gene called c-raf.

First, they put the gene on a large circular piece of DNA called a plasmid, along with the gene for a reverse transcriptase (RT), a viral protein that copies RNA back into DNA.

When the plasmid was injected into a lung cancer cell, it produced a long RNA strand containing a copy of both genes. The cell used the RNA to make the RT protein which, in turn, began to copy the RNA back into the DNA enzyme.

When the RT got to the end of the tiny DNA fragment, it was pushed off by a twist that had been engineered into the RNA. Once derailed, the RT displayed another ability: it chewed the RNA away, releasing the DNA enzyme.

Once free, the DNA enzyme was able to chop up about 65 per cent of the c-raf RNA in 48 hours. Even this amount of DNA-induced destruction was enough to stop the cancer program of many of the cells and drive them to self-destruct.

"This is only the beginning," says Chen. "We are still trying to improve the system."

This work was presented at the Gene Therapy 2001: A Gene Odyssey meeting in Snowbird, Utah, US. See our special section for more coverage.


http://www.newscientist.com/article.ns?id=dn308