Study catches picture of deadly cancer enzyme

WASHINGTON (Reuters) - Scientists have captured an image ofan enzyme key to the progression of the deadliest cancers andsaid on Wednesday their findings may lead to new therapiesagainst not only cancer, but HIV and diabetes too.

They caught in the act a mutant version of an enzyme calledp300/CBP, which is involved in pancreatic, colon, and lungcancers, thyroid cancer and some leukaemias.

The image of this structure might provide a way to design adrug that blocks it, and perhaps stop some tumour-causingmutations.

The same structure is involved in infection with the AIDSvirus and diabetes, as well, said Dr. Philip Cole, a professorand director of pharmacology and molecular sciences at JohnsHopkins University in Baltimore.

"If we could wipe all those, we would have a lot fewerdeaths," Cole said in a telephone interview.

Writing in the journal Nature, Cole and colleagues at theWistar Institute and the University of Pennsylvania said theenzyme acted in a hit-and-run fashion, working so quickly ithad been difficult to image it. Without an image, it is hard toknow precisely how to counter its effects.

The enzyme p300/CBP is a transcription factor, one of alarge family of enzymes that unwrap DNA from around otherproteins known as histones.

Cole said a delicate balance of p300 was needed, as eithertoo much or too little can both lead to cancer.

"There is definitely some evidence that blocking thisenzyme in the host may make it harder for HIV to bepathogenic," Cole added.

His lab has a compound that interferes with p300 but now itmay be possible to make a better one, he said.

"We've had a chemical inhibitor of p300 for about nineyears now, but without the structure, we had no idea how it wasworking or, more importantly, how to improve on it," he said.

"We're still in our infancy of understanding how to goafter cancer," Cole added. "But this definitely is a step inthe right direction."

The study may also help explain how some natural productscan affect cancer. Curcumin, the compound that makes the spiceturmeric yellow, has been shown in studies to interfere withp300/CBP.

(Editing by Will Dunham and Peter Cooney)