Colon Cancer and Bacteria
Both gram negative and gram positive bacteria play a key role in cancer; Escherichia coli and Streptococcus bovis are two types of bacteria that have been identified for having a central role in the pathogenesis of colon cancer.[1] [2]
There is evidence that it is fermented carbohydrates rather than meat that are responsible for the overgrowth of the bacteria that are linked to colon cancer. Both gram negative bacteria and Streptococcus bovis, the gram positive bacteria multiply when there is an abundance of carbohydrates for them to eat. [3][4]
Gram Negative Bacteria (The LPS Producers)
Gram negative bacteria contain LPS (endotoxin). LPS has been linked to many diseases and even cancer.[5] Bacterial endotoxin (LPS) enhances colorectal cancer cell adhesion and invasion through TLR-4 and NF-κB dependent activation of the urokinase plasminogen activator system.[6]
LPS affects the host through CD 14, the receptor for LPS.
The central role of LPS in colon cancer can be seen by the fact that the gene for CD14, the receptor of LPS, is a good marker for susceptibility to colon cancer.[7](This experiment was done in China with Han Chinese patients; Han is the name of the biggest ethnic group in China.) It was found that there are significant differences in CD14 genotypes between healthy controls and patients with colorectal cancer. Thus the CD14 gene may contribute to the predisposition to colorectal cancer.[7]
Explanation why the gene for the LPS receptor would be very important:
"Transgenic mice overexpressing human CD14 show increased susceptibility to endotoxin (LPS)shock, whereas CD14-deficient mice are highly resistant to either live gram-negative bacteria or LPS. CD14-deficient mice also show dramatically reduced levels of bacteremia following in vivo challenge with E. coli, suggesting a role for CD14 in dissemination of gram-negative bacteria."[8]
Adherent Escherichia coli is an example of an adherent gram negative bacteria that has been found to be overgrown in colon cancer patients in comparison to controls. E. coli expressed hemagglutinins was found in 39% of Crohn's cases and 38% of cancers but only in 4% of controls.[1] E. coli, including nonadherent isolates, induced interleukin-8 release from the cell lines.[1] "These studies support a central role for mucosally adherent bacteria in the pathogenesis of Crohn's disease and colon cancer".[1]
Colon Cancer and Positive Gram Bacteria
We have a collection of additional articles linking Streptococcus bovis to colon cancer. These are available on another web page on this website.
View articles in PubMed about the link between cancer and Streptococcus bovis
References
1. Helen M. Martin , Barry J. Campbell , C.Anthony Hart , Chiedzo Mpofu , Manu Nayar , Ravinder Singh , Hans Englyst , Helen F. Williams , Jonathan M. Rhodes. Enhanced Escherichia coli adherence and invasion in Crohn’s disease and colon cancer. Gastroenterology- 2004 July (Vol. 127, Issue 1) View this article in Gastroenterology
2. Biarc J, Nguyen IS, Pini A, Gossé F, Richert S, Thiersé D, Van Dorsselaer A, Leize-Wagner E, Raul F, Klein JP, Schöller-Guinard M. Carcinogenic properties of proteins with pro-inflammatory activity from Streptococcus infantarius (formerly S.bovis). Carcinogenesis. 2004 Aug;25(8):1477-84. Epub 2004 Jan 23. View this article in PubMed
3. See the section of this website about Diet and LPS.
4. Cheng KJ, McAllister TA, Popp JD, Hristov AN, Mir Z, Shin HT. A review of bloat in feedlot cattle. J Anim Sci. 1998 Jan;76(1):299-308. View this article in PubMed
5. This website has a collection of articles linking LPS to many chronic illnesses. On the right of this website, there is section with links to the chronic conditions that are affected by LPS.
6. S.D. Killeen , J.H. Wang , E.J. Andrews , W. Schmalix , B. Muehlenweg , H.P. Redmond. Bacterial endotoxin enhances colorectal cancer cell adhesion and invasion through TLR-4 and NF-κB dependent activation of the urokinase plasminogen activator system. Journal of Surgical Research- 2006 February (Vol. 130, Issue 2). Link to Journal of Surgical Research
7. Guo Q, Zhu J, Xia B. Polymorphism of CD14 gene but not the mutation of TLR4 gene is associated with colorectal cancer in Chinese patients. J Gastroenterol Hepatol. 2006 Jan;21(1 Pt 1):92-7. View this article in PubMed