Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:


Bacterial protein kills tumors


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:

More articles from Health and Medicine:

nachricht Advanced analysis of brain structure shape may track progression to Alzheimer's disease
26.10.2016 | Massachusetts General Hospital

nachricht Indian roadside refuse fires produce toxic rainbow
26.10.2016 | Duke University

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: Etching Microstructures with Lasers

Ultrafast lasers have introduced new possibilities in engraving ultrafine structures, and scientists are now also investigating how to use them to etch microstructures into thin glass. There are possible applications in analytics (lab on a chip) and especially in electronics and the consumer sector, where great interest has been shown.

This new method was born of a surprising phenomenon: irradiating glass in a particular way with an ultrafast laser has the effect of making the glass up to a...

Im Focus: Light-driven atomic rotations excite magnetic waves

Terahertz excitation of selected crystal vibrations leads to an effective magnetic field that drives coherent spin motion

Controlling functional properties by light is one of the grand goals in modern condensed matter physics and materials science. A new study now demonstrates how...

Im Focus: New 3-D wiring technique brings scalable quantum computers closer to reality

Researchers from the Institute for Quantum Computing (IQC) at the University of Waterloo led the development of a new extensible wiring technique capable of controlling superconducting quantum bits, representing a significant step towards to the realization of a scalable quantum computer.

"The quantum socket is a wiring method that uses three-dimensional wires based on spring-loaded pins to address individual qubits," said Jeremy Béjanin, a PhD...

Im Focus: Scientists develop a semiconductor nanocomposite material that moves in response to light

In a paper in Scientific Reports, a research team at Worcester Polytechnic Institute describes a novel light-activated phenomenon that could become the basis for applications as diverse as microscopic robotic grippers and more efficient solar cells.

A research team at Worcester Polytechnic Institute (WPI) has developed a revolutionary, light-activated semiconductor nanocomposite material that can be used...

Im Focus: Diamonds aren't forever: Sandia, Harvard team create first quantum computer bridge

By forcefully embedding two silicon atoms in a diamond matrix, Sandia researchers have demonstrated for the first time on a single chip all the components needed to create a quantum bridge to link quantum computers together.

"People have already built small quantum computers," says Sandia researcher Ryan Camacho. "Maybe the first useful one won't be a single giant quantum computer...

All Focus news of the innovation-report >>>



Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

Agricultural Trade Developments and Potentials in Central Asia and the South Caucasus

14.10.2016 | Event News

World Health Summit – Day Three: A Call to Action

12.10.2016 | Event News

Latest News

The gene of autumn colours

27.10.2016 | Life Sciences

Polymer scaffolds build a better pill to swallow

27.10.2016 | Life Sciences

Greater Range and Longer Lifetime

26.10.2016 | Power and Electrical Engineering

More VideoLinks >>>