Clear Links Found Between Inflammation, Bacterial Communities and Cancer

[Darwinsbulldog]

ScienceDaily (Aug. 16, 2012) — What if a key factor ultimately behind a cancer was not a genetic defect but ecological?
Ecologists have long known that when some major change disturbs an environment in some way, ecosystem structure is likely to change dramatically. Further, this shift in interconnected species' diversity, abundances, and relationships can in turn have a transforming effect on health of the whole landscape -- causing a rich woodland or grassland to become permanently degraded, for example -- as the ecosystem becomes unstable and then breaks down the environment.
For this reason, it should come as no surprise that a significant disturbance in the human body can profoundly alter the makeup of otherwise stable microbial communities co-existing within it and that changes in the internal ecology known as the human microbiome can result in unexpected and drastic consequences for human health.
A report published in the August 16 online edition of the journal Science gives evidence for such a chain reaction. It has long been known that gut inflammation is a risk factor for cancer. The new study suggests that this may be in part because inflammation disturbs gut ecosystems leading to conditions that allow pathogens to invade the gut. These pathogens may damage host cells increasing the risk of the development of colorectal cancer.
The authors of the study were Janelle C. Arthur, Ernesto Perez-Chanona, Marcus Mühlbauer, Sarah Tomkovich, Joshua M. Uronis, Ting-Jia Fan, Christian Jobin, Arlin B. Rogers, Jonathan J. Hansen, and Temitope O. Keku from the University of North Carolina at Chapel Hill; Barry J. Campbell and Jonathan M. Rhodes from the University of Liverpool; Turki Abujamel and Alain Stintzi from the University of Ottawa; Belgin Dogan and Kenneth W. Simpson from Cornell University; and Anthony A. Fodor from the University of North Carolina at Charlotte.

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http://www.sciencedaily.com/releases...0816141527.htm

Arthur, J. C., E. Perez-Chanona, et al. (2012). "Intestinal Inflammation Targets Cancer-Inducing Activity of the Microbiota." Science.

Inflammation alters host physiology to promote cancer, as seen in colitis-associated colorectal cancer (CRC). Here, we identify the intestinal microbiota as a target of inflammation that impacts the progression of CRC. High-throughput sequencing revealed that inflammation modifies gut microbial composition in colitis-susceptible interleukin-10–deficient (Il10−/−) mice. Monocolonization with the commensal Escherichia coli NC101 promoted invasive carcinoma in azoxymethane (AOM)–treated Il10−/− mice. Deletion of the polyketide synthase (pks) genotoxic island from E. coli NC101 decreased tumor multiplicity and invasion in AOM/Il10−/− mice, without altering intestinal inflammation. Mucosa-associated pks+ E. coli were found in a significantly high percentage of inflammatory bowel disease and CRC patients. This suggests that in mice, colitis can promote tumorigenesis by altering microbial composition and inducing the expansion of microorganisms with genotoxic capabilities.

http://www.sciencemag.org/content/ea...24820.abstract