With new grant, UF microbiologist seeks to incite cancer cell suicide

Deadly, versatile, complex and ubiquitous: These are adjectives scientists have employed to describe the strain of bacteria known as Pseudomonas aeruginosa.

To a healthy person, the bacteria are silent, harmless neighbors prevalent throughout the environment. Yet they are a growing threat in hospitals and are adept at resisting antibiotics. Chronic infection can prove fatal, particularly to people who have cystic fibrosis or weakened immune systems.

Intriguingly, the fearsome single-cell organism also may be able to teach University of Florida researchers how to kill cancer cells. With a new four-year, $1 million grant from the American Cancer Society, microbiologist Shouguang Jin is seeking a better understanding of how the bacteria are able to incite suicide in cells they interact with.

“Last year we were able to demonstrate that this bacterium injects a protein named ExoS into its host, triggering a kind of programmed cell death known as apoptosis,” said Jin, an associate professor in the College of Medicine’s department of molecular genetics and microbiology.

“Today in cancer research, there are extensive studies on the mechanism of apoptosis,” said Jin, who also is affiliated with the UF Genetics Institute and the UF Powell Gene Therapy Center. “The idea is that if you can trigger cancer cells to go through apoptosis, you can kill them. Pseudomonas may provide an avenue for understanding how to trigger this process.”

Jin also is looking for better ways to fight Pseudomonas infection, which is linked to 16 percent of hospital-acquired pneumonia cases, according to the U.S. Centers for Disease Control and Prevention. Improved measures could help prolong the lives of people with cystic fibrosis or AIDS. People undergoing cancer treatment also are susceptible to severe infection.

“It’s tough to treat a Pseudomonas infection because the bacterium becomes resistant to so many antibiotics,” Jin said. “Initially when you treat cystic fibrosis patients, for example, you can kill the bacteria. But after a number of years, the bacteria that persist in their lungs become resistant to all antibacterial treatment.”

Jin, whose research also is supported by a new three-year, $450,000 grant from the Cystic Fibrosis Foundation, is seeking an understanding of which genes in the bacterium control the process of infection. Once that is understood, scientists can try to develop treatments that can interfere with key steps in that process, Jin said.