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Engineered Bacteria Target Tumors (BioTechniques Newsletter_2012 1)
작성자 이규호 작성일 12-02-03 10:10 조회 3,033
Engineered Bacteria Target Tumors
01/30/2012 David Pittman
http://www.biotechniques.com/news/Engineered-Bacteria-Target-Tumors/
 
Cancer drug delivery takes another step forward as scientists prove bioluminescent bacteria can target solid tumors and bypass healthy cells.
 
One of the biggest problems in the development of cancer therapies has been the targeting of harmful tumor cells for treatment while leaving the healthy, normal cells untouched. To overcome this, scientists have been developing methods to deliver chemotherapy straight to cancer calls. A research team at the University of College Cork (UCC) in Ireland believes they’ve taken a key step in one area, using engineered bacteria.
 
Led by principal investigator Mark Tangney at the university’s Cork Cancer Research Center, the team designed a light-emitting bacteria that flows directly to cancer cells after being injected into a mouse with the disease and can produce a readable 3-D image of tumors. The results were published in the January 25 edition of the online journal Public Library of Science One, including 3-D images that show these bacteria can travel through the body but only grow within tumors. Because these engineered bacteria grow preferentially within these tumor cells, making them an attractive option for drug delivery.
 
“We can now genetically engineer these bacteria so that they will pump out anti-cancer agents specifically inside tumors,” said study author Michelle Cronin, an Irish Cancer Society Research Fellow at UCC. “We are testing our engineered strains in numerous tumor models and as we function as a translational research center, we hope to progress the concept to pre-clinical trials.”
 
In their experiment, Tangney and colleagues infused a non-pathogenic strain of Escherichia coli and Bifidobacterium breve intravenously under the skin of tumor-containing mice. The bacteria were engineered to express an exact gene that causes it to emit a light that can be detected in the body.
 
Previously, 2-D bioluminescence imaging allowed researchers to obtain only a rough approximation of where a tumor was in the body, requiring other methods to pinpoint a tumor’s exact location. But recent advances in 3-D optical tomography have allowed researchers to gain precise information about the number and location of bioluminescent bacteria, revealing more information about the tumor in question.
 
The team had to turn to using certain commensal or probiotic strains of bacteria so the body didn’t attack the bacteria causing it to be ingested into healthy cells. “The pathogenic salmonella strain persists in healthy tissue in the mouse whereas the commensal strains do not, they colonize the tumors specifically,” Cronin said. “This is particularly important to us as we don't want to choose a strain of bacteria that will deliver a therapeutic gene to healthy tissue we only wish to target tumors.”
 
Cronin expects the results to have broad applicability to all types of solid tumors because, despite the various differences in their composition, all foster this sort of bacterial growth.
 
Reference
Cronin et al. 2012. High resolution in vivo bioluminescent imaging for the study of bacterial tumour targeting. PLoS ONE 7: e30940.
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