Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Sea creature's toxin could lead to promising cancer treatment

07.02.2007
A toxin derived from a reclusive sea creature resembling a translucent doughnut has inspired UT Southwestern Medical Center researchers to develop a related compound that shows promise as a cancer treatment.

In a study appearing online this week in the Proceedings of the National Academy of Sciences, the UT Southwestern scientists detail how the toxin blocks uninhibited reproduction of cultured human cancer cells while leaving healthy cells unaffected.

An accompanying study in PNAS shows that, in pre-clinical trials, a synthetic form of the toxin reduced human tumors implanted in mice without the harmful side effects seen using other cancer drugs. "Diazonamide is a special molecule – it's teaching us more than we imagined," said Dr. Patrick Harran, professor of biochemistry and a senior author on both studies.

"This is a truly exciting result," said Dr. John Schwab, a program officer at the National Insti tutes of Health's National Institute of General Medical Sciences, which partly funded the work. "Not only has this UT Southwestern team identified a potent anti-cancer drug, but its unique mode of action avoids the kinds of side effects that make cancer chemotherapy so difficult. It's a great example of how NIH support for fundamental chemical research can benefit the American health-care consumer."

The animal, Diazona angulata, is a sea squirt a few inches wide that lives in colonies anchored to rocks. It was discovered offshore of the Philippines in 1990 as scientists were looking for species that might lead to useful drugs. From a few specimens, scientists extracted a tiny amount of a toxin, diazonamide A, which the animal probably uses to repel predators.

The toxin proved to kill cancer cells in culture, but so little of its natural form was available that a race soon began to synthesize it in the laboratory.

A chemical structure for diazonamide A was published in 1991, but in 2001, Dr. Harran's group showed that initial report to be incorrect, and uncovered the correct structure. In the first of the two new studies, Dr. Harran and his co-workers synthesized several variants of diazonamide A in order to pin down how it prevents cancer cells from dividing.

Normal cell division involves a structure called the mitotic spindle, which pulls apart the chromosomes before the cell splits. The spindle is primarily made out of a substance called tubulin. Some anti-cancer drugs attack tubulin, but they have serious side effects, such as nerve damage and depletion of bone marrow and white blood cells.

The UT Southwestern researchers found that while diazonamide A blocked cell division, it seemed not to bind directly to tubulin. Instead, Dr. Xiaodong Wang, professor of biochemistry, and Dr. Gelin Wang, instructor of biochemistry, found that the toxin interacted with an enzyme called OAT, which was known to be involved in cellular metabolism but had no previously known role in cell division.

Interestingly, diazonamide did not block OAT's enzyme activity, the researchers said. Rather, it uncovered a second function for the protein in cell division.

"The finding that OAT is the cellular target of diazonamide is surprising for two reasons: First, there is no previous report that a mitochondrial enzyme like OAT can play a direct role in mitosis; second, OAT seems dispensable for normal cell division occurring in mice and men but is required for the division of cancer cells. This may explain the cancer specificity of diazonamide," said Dr. Wang, who is also a Howard Hughes Medical Institute investigator.

Dr. Noelle Williams, assistant professor of biochemistry and internal medicine, led the second phase of the research, which tested the effect of a variant of diazonamide A, called AB-5, in mice with tumors.

AB-5 has a structure nearly identical to diazonamide A and is indistinguishable in its biological action, but is easier to synthesize in the lab.

The researchers tested AB-5's effectiveness against cancer by implanting human tumor cells under the skin of m ice and treating them with either paclitaxel (Taxol) or vinblastine – both approved drugs currently used – or AB-5. The trial used tumor cells from human prostate, breast and colon cancers.

While all three drugs reduced tumors in the mice, the known drugs caused significant weight loss and loss of white blood cells while AB-5 caused neither side effect. "That the diazonamide toxin blocks mitosis selectively in cancer cells is almost too desirable an outcome to be true," said Dr. Steven McKnight, chairman of biochemistry and senior author of the second study. "As with any other unanticipated scientific discovery, the validity of these observations will be held to appropriately diligent scrutiny."

Aline McKenzie | EurekAlert!
Further information:
http://www.utsouthwestern.edu

Further reports about: Biochemistry Cancer OAT Toxin diazonamide structure white blood cell

More articles from Life Sciences:

nachricht The birth of a new protein
20.10.2017 | University of Arizona

nachricht Building New Moss Factories
20.10.2017 | Albert-Ludwigs-Universität Freiburg im Breisgau

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Neutron star merger directly observed for the first time

University of Maryland researchers contribute to historic detection of gravitational waves and light created by event

On August 17, 2017, at 12:41:04 UTC, scientists made the first direct observation of a merger between two neutron stars--the dense, collapsed cores that remain...

Im Focus: Breaking: the first light from two neutron stars merging

Seven new papers describe the first-ever detection of light from a gravitational wave source. The event, caused by two neutron stars colliding and merging together, was dubbed GW170817 because it sent ripples through space-time that reached Earth on 2017 August 17. Around the world, hundreds of excited astronomers mobilized quickly and were able to observe the event using numerous telescopes, providing a wealth of new data.

Previous detections of gravitational waves have all involved the merger of two black holes, a feat that won the 2017 Nobel Prize in Physics earlier this month....

Im Focus: Smart sensors for efficient processes

Material defects in end products can quickly result in failures in many areas of industry, and have a massive impact on the safe use of their products. This is why, in the field of quality assurance, intelligent, nondestructive sensor systems play a key role. They allow testing components and parts in a rapid and cost-efficient manner without destroying the actual product or changing its surface. Experts from the Fraunhofer IZFP in Saarbrücken will be presenting two exhibits at the Blechexpo in Stuttgart from 7–10 November 2017 that allow fast, reliable, and automated characterization of materials and detection of defects (Hall 5, Booth 5306).

When quality testing uses time-consuming destructive test methods, it can result in enormous costs due to damaging or destroying the products. And given that...

Im Focus: Cold molecules on collision course

Using a new cooling technique MPQ scientists succeed at observing collisions in a dense beam of cold and slow dipolar molecules.

How do chemical reactions proceed at extremely low temperatures? The answer requires the investigation of molecular samples that are cold, dense, and slow at...

Im Focus: Shrinking the proton again!

Scientists from the Max Planck Institute of Quantum Optics, using high precision laser spectroscopy of atomic hydrogen, confirm the surprisingly small value of the proton radius determined from muonic hydrogen.

It was one of the breakthroughs of the year 2010: Laser spectroscopy of muonic hydrogen resulted in a value for the proton charge radius that was significantly...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ASEAN Member States discuss the future role of renewable energy

17.10.2017 | Event News

World Health Summit 2017: International experts set the course for the future of Global Health

10.10.2017 | Event News

Climate Engineering Conference 2017 Opens in Berlin

10.10.2017 | Event News

 
Latest News

Terahertz spectroscopy goes nano

20.10.2017 | Information Technology

Strange but true: Turning a material upside down can sometimes make it softer

20.10.2017 | Materials Sciences

NRL clarifies valley polarization for electronic and optoelectronic technologies

20.10.2017 | Interdisciplinary Research

VideoLinks
B2B-VideoLinks
More VideoLinks >>>