Featured Research

from universities, journals, and other organizations

How a cancer-causing bacterium spurs cell death

Date:
November 2, 2011
Source:
University of Illinois at Urbana-Champaign
Summary:
Researchers report they have figured out how the cancer-causing bacterium Helicobacter pylori attacks a cell's energy infrastructure, sparking a series of events in the cell that ultimately lead it to self-destruct. H. pylori are the only bacteria known to survive in the human stomach. Infection with the bacterium is associated with an increased risk of gastric cancer, the second-leading cause of cancer-related deaths worldwide.

Microbiology professor Steven Blanke, right; doctoral student Prashant Jain and a colleague at Purdue University found a mechanism linking Helicobacter pylori infection, impairment of the mitochondria and cell death.
Credit: L. Brian Stauffer

Researchers report they have figured out how the cancer-causing bacterium Helicobacter pylori attacks a cell's energy infrastructure, sparking a series of events in the cell that ultimately lead it to self-destruct.

Related Articles


H. pylori are the only bacteria known to survive in the human stomach. Infection with the bacterium is associated with an increased risk of gastric cancer, the second-leading cause of cancer-related deaths worldwide.

"More than half the world's population is currently infected with H. pylori," said University of Illinois microbiology professor Steven Blanke, who led the study. "And we've known for a long time that the host doesn't respond appropriately to clear the infection from the stomach, allowing the bacterium to persist as a risk factor for cancer."

The new study, in Proceedings of the National Academy of Sciences, is the first to show how a bacterial toxin can disrupt a cell's mitochondria -- its energy-generation and distribution system -- to disable the cell and spur apoptosis (programmed cell death).

"One of the hallmarks of long-term infection with H. pylori is an increase in apoptotic cells," Blanke said. "This may contribute to the development of cancer in several ways." Apoptosis can damage the epithelial cells that line the stomach, he said, "and chronic damage to any tissue is a risk factor for cancer." An increase in apoptotic cells may also spur the hyper-proliferation of stem cells in an attempt to repair the damaged tissue, increasing the chance of mutations that can lead to cancer.

Previous studies had shown that VacA, a protein toxin produced by H. pylori, induces host cell death, Blanke said, "but the mechanism had been unknown."

The VacA protein was known to target the mitochondrion, an organelle that produces chemical energy where it is needed in the cell. In healthy cells, mitochondria fuse to form elaborate energy-generating networks in response to cellular needs. Mitochondria are important to a lot of other cellular processes; most important to Blanke and his colleagues, they regulate cell death.

While studying how a cell responds to infection, the researchers noticed that H. pylori induced mitochondrial fission. Instead of fusing and forming filamentous networks to respond to the cell's energy needs, the mitochondria were breaking into smaller, unconnected organelles.

"Fusion and fission are two dynamic and opposing processes that must be balanced to regulate mitochondrial structure and function," Blanke said. But infection with H. pylori -- or with purified VacA toxin alone -- was pushing the mitochondria toward fission.

The researchers found that VacA recruited a host protein, Drp1, to the mitochondria. This protein plays a central role in mitochondrial fission. Further experiments showed that Drp1-mediated fission of the mitochondrial networks was linked to activation of a cell-death-inducing factor, called Bax.

"The link between VacA action at the mitochondria and Bax-dependent cell death had previously been unknown," Blanke said.

This study provides a first direct link between a bacterial toxin-mediated disruption of mitochondrial dynamics and host cell death, Blanke said. It also opens a new avenue of investigation of other diseases linked to impaired mitochondrial function, he said.

"Hundreds of human diseases and disorders are associated with mitochondrial dysfunction, ranging from cancers to degenerative diseases such as Alzheimer's disease and Parkinson's," Blanke said. "As yet, no one has methodically investigated a potential link between bacterial infections and mitochondrial diseases, despite the fact that several dozen pathogenic bacteria and viruses are known to directly target mitochondria."

Blanke and his colleagues are beginning to investigate that link.

"To us, finding that a pathogen can disrupt mitochondria in a manner that has striking similarities to what has been observed in known mitochondrial diseases is potentially very exciting," said Blanke, who also is an affiliate of the Institute for Genomic Biology at Illinois.

The research team included Illinois doctoral student Prashant Jain and Professor Zhao-Qing Luo, of Purdue University.


Story Source:

The above story is based on materials provided by University of Illinois at Urbana-Champaign. Note: Materials may be edited for content and length.


Journal Reference:

  1. P. Jain, Z.-Q. Luo, S. R. Blanke. Helicobacter pylori vacuolating cytotoxin A (VacA) engages the mitochondrial fission machinery to induce host cell death. Proceedings of the National Academy of Sciences, 2011; 108 (38): 16032 DOI: 10.1073/pnas.1105175108

Cite This Page:

University of Illinois at Urbana-Champaign. "How a cancer-causing bacterium spurs cell death." ScienceDaily. ScienceDaily, 2 November 2011. <www.sciencedaily.com/releases/2011/11/111101130202.htm>.
University of Illinois at Urbana-Champaign. (2011, November 2). How a cancer-causing bacterium spurs cell death. ScienceDaily. Retrieved March 28, 2015 from www.sciencedaily.com/releases/2011/11/111101130202.htm
University of Illinois at Urbana-Champaign. "How a cancer-causing bacterium spurs cell death." ScienceDaily. www.sciencedaily.com/releases/2011/11/111101130202.htm (accessed March 28, 2015).

Share This


More From ScienceDaily



More Health & Medicine News

Saturday, March 28, 2015

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

S. Leone in New Anti-Ebola Lockdown

S. Leone in New Anti-Ebola Lockdown

AFP (Mar. 28, 2015) — Sierra Leone imposed a three-day nationwide lockdown Friday for the second time in six months in a bid to prevent a resurgence of the deadly Ebola virus. Duration: 01:17 Video provided by AFP
Powered by NewsLook.com
These Popular Antibiotics Can Cause Permanent Nerve Damage

These Popular Antibiotics Can Cause Permanent Nerve Damage

Newsy (Mar. 27, 2015) — A popular class of antibiotic can leave patients in severe pain and even result in permanent nerve damage. Video provided by Newsy
Powered by NewsLook.com
WH Plan to Fight Antibiotic-Resistant Germs

WH Plan to Fight Antibiotic-Resistant Germs

AP (Mar. 27, 2015) — The White House on Friday announced a five-year plan to fight the threat posed by antibiotic-resistant bacteria amid fears that once-treatable germs could become deadly. (March 27) Video provided by AP
Powered by NewsLook.com
House Ready to Pass Medicare Doc Bill

House Ready to Pass Medicare Doc Bill

AP (Mar. 26, 2015) — In rare bipartisan harmony, congressional leaders pushed a $214 billion bill permanently blocking physician Medicare cuts toward House passage Thursday, moving lawmakers closer to resolving a problem that has plagued them for years. (March 26) Video provided by AP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
 
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:  

Breaking News:

Strange & Offbeat Stories

 

Health & Medicine

Mind & Brain

Living & Well

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:  

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile iPhone Android Web
Follow Facebook Twitter Google+
Subscribe RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins