Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Bacterial protein kills tumors

28.10.2002


New weapon in the fight against cancer?



The use of live bacteria to treat cancer goes back a hundred years. But while the therapy can sometimes shrink tumors, the treatment usually leads to toxicity, limiting its value in medicine.

Now, researchers at the University of Illinois at Chicago have isolated a protein secreted by bacteria that kills cancer cells but appears to have no harmful side effects. Tested in mice injected with human melanomas, the protein shrank the malignancies, but, in contrast with other studies using whole bacteria, caused no deaths or adverse reactions in the laboratory animals.


"Bacterial proteins could well be a new weapon in the war against cancer," said Ananda Chakrabarty, distinguished professor of microbiology and immunology and one of the study’s investigators.

Results of the three-year-long study are published in the October 29 issue of the Proceedings of the National Academy of Sciences.

Oddly, the protein the researchers isolated is a well-studied molecule called azurin that is involved in the everyday process cells use to generate energy. This is the first report, however, that azurin is an effective anticancer agent.

The protein was isolated from the growth medium of Pseudomonas aeruginosa, a bacterium that is often resistant to antibiotics and causes serious respiratory infections in people who are particularly susceptible, such as patients with cystic fibrosis or severe burns. The bacterium protects itself from destruction by killing macrophages, the immune system’s first line of attack against a foreign body.

In the UIC study, specially-bred immunodeficient mice implanted with human melanoma were treated with half a milligram of azurin daily for 22 days. At the conclusion of the trial, the average size of the tumors in these mice was 60 percent smaller than those in untreated mice. None of the mice showed signs of illness or loss of weight.

The researchers said that azurin appears to work by stabilizing the p53 protein, a product of the p53 gene, known as a tumor suppressor because it prevents the formation of cancers through a cascade of molecular events that either stops cells from dividing or induces a process called programmed cell death. Normally, the p53 protein is short-lived, surviving just a few minutes in the cell before degrading. But azurin winds its way into the nucleus of the tumor cell, where it binds to the p53 protein and protects it from degradation, thus raising its level within the cell.

According to Dr. Tapas Das Gupta, a co-investigator and head of surgical oncology at UIC, preliminary data show that azurin kills several types of cancer cells, including breast and colon cancer.

"These results suggest that azurin could be a useful anticancer agent not just for melanoma but for different kinds of tumors," Das Gupta said. But he cautioned that extensive studies are needed to confirm the inital laboratory results.

The first observation that bacteria can thwart tumors was made in 1893 by New York physician William Coley, who found that bone cancer patients who contracted bacterial infections survived longer.

Much more recently, researchers at Johns Hopkins University used anaerobic bacteria, bacteria that thrive without oxygen, to destroy the hard cores of tumors. Radiation and chemotherapy are ineffective in these areas because they lack blood and oxygen. In the Hopkins studies, whole "de-fanged" bacteria were used. But although their tumors shrank, a large proportion of the experimental mice died, presumably because of toxins released either by the bacteria or the dying cancer cells.

"Our research suggests we can achieve a therapeutic outcome using bacterial proteins, without the toxicity associated with live bacteria," Chakrabarty said.


Other authors of the study were UIC researchers Tohru Yamada, Masatoshi Goto, Vasu Punj, Olga Zaborina, Mei Ling Chen, Kazuhide Kimbara, Dibyen Majumdar and Elizabeth Cunningham.

The study was supported by grants from the National Institute of Environmental Health Sciences, the National Institute of Allergy and Infectious Diseases and the National Cancer Institute.

Sharon Butler | EurekAlert!
Further information:
http://www.uic.edu

More articles from Health and Medicine:

nachricht Laser activated gold pyramids could deliver drugs, DNA into cells without harm
24.03.2017 | Harvard John A. Paulson School of Engineering and Applied Sciences

nachricht What does congenital Zika syndrome look like?
24.03.2017 | University of California - San Diego

All articles from Health and Medicine >>>

The most recent press releases about innovation >>>

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

Im Focus: Giant Magnetic Fields in the Universe

Astronomers from Bonn and Tautenburg in Thuringia (Germany) used the 100-m radio telescope at Effelsberg to observe several galaxy clusters. At the edges of these large accumulations of dark matter, stellar systems (galaxies), hot gas, and charged particles, they found magnetic fields that are exceptionally ordered over distances of many million light years. This makes them the most extended magnetic fields in the universe known so far.

The results will be published on March 22 in the journal „Astronomy & Astrophysics“.

Galaxy clusters are the largest gravitationally bound structures in the universe. With a typical extent of about 10 million light years, i.e. 100 times the...

Im Focus: Tracing down linear ubiquitination

Researchers at the Goethe University Frankfurt, together with partners from the University of Tübingen in Germany and Queen Mary University as well as Francis Crick Institute from London (UK) have developed a novel technology to decipher the secret ubiquitin code.

Ubiquitin is a small protein that can be linked to other cellular proteins, thereby controlling and modulating their functions. The attachment occurs in many...

Im Focus: Perovskite edges can be tuned for optoelectronic performance

Layered 2D material improves efficiency for solar cells and LEDs

In the eternal search for next generation high-efficiency solar cells and LEDs, scientists at Los Alamos National Laboratory and their partners are creating...

Im Focus: Polymer-coated silicon nanosheets as alternative to graphene: A perfect team for nanoelectronics

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are less stable. Now researchers at the Technical University of Munich (TUM) have, for the first time ever, produced a composite material combining silicon nanosheets and a polymer that is both UV-resistant and easy to process. This brings the scientists a significant step closer to industrial applications like flexible displays and photosensors.

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are...

Im Focus: Researchers Imitate Molecular Crowding in Cells

Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to simulate these confined natural conditions in artificial vesicles for the first time. As reported in the academic journal Small, the results are offering better insight into the development of nanoreactors and artificial organelles.

Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

International Land Use Symposium ILUS 2017: Call for Abstracts and Registration open

20.03.2017 | Event News

CONNECT 2017: International congress on connective tissue

14.03.2017 | Event News

ICTM Conference: Turbine Construction between Big Data and Additive Manufacturing

07.03.2017 | Event News

 
Latest News

Argon is not the 'dope' for metallic hydrogen

24.03.2017 | Materials Sciences

Astronomers find unexpected, dust-obscured star formation in distant galaxy

24.03.2017 | Physics and Astronomy

Gravitational wave kicks monster black hole out of galactic core

24.03.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>