SUMMARY: CANCER MICROBIOME. Be it linked to the gut microbiome or specific tissue,… It was just a matter of time until researchers linked cancer to the microbiome.
“These studies demonstrate that microbiota can increase or decrease cancer susceptibility and progression by diverse mechanisms such as by modulating inflammation, influencing the genomic stability of host cells and producing metabolites that function as histone deacetylase inhibitors to epigenetically regulate host gene expression. One might consider microbiota as tractable environmental factors because they are highly quantifiable and relatively stable within an individual compared with our exposures to external agents. At the same time, however, diet can modulate the composition of microbial communities within our gut, and this supports the idea that probiotics and prebiotics can be effective chemoprevention strategies. The trajectory of where the current work is headed suggests that microbiota will continue to provide insight into the basic mechanisms of carcinogenesis and that microbiota will also become targets for therapeutic intervention.” – Emerging roles of the microbiome in cancer, Carcinogenesis. 2013 Dec 3. [Epub ahead of print]
A word on “diet“
I actually hate that these researchers equate diet impact on microbiome as limited to pro and prebiotics when we now know that long term diet changes do effect microbiome changes. Read the post, “OPTIMAL MICROBIOME DIET FROM AMERICAN GUT DATA,“ a synopsis of Dr. Rob Knight’s work at UColorado Boulder, or the post “THE SCIENCE BEHIND FOOD, DISEASE, MICROBIOME“ for more insight on the role of long diet and microbiome stability. I suppose another way of expressing this concept: it took a long time eating the way we are to establish our microbiome; it should be no surprise that it will take a long time (though often immediate health symptom alleviation is realized upon initiating gut healing protocols) to alter the microbiome to become a stable microbiome.
This is often what newbies to the Specific Carbohydrate Diet (SCD) diet are told when they question and look for timing estimates for quick though stable change. SCD is a dietary therapeutic that people generally use to augment treatment, or use solely to achieve remission, of chronic disease and autoimmunes such as IBD or non-responsive gluten-free celiac. Other similar gut healing diets are called GAPS, PALEO and Autoimmune Protocols… The post “FOOD MANAGING IBD & AUTISM: THE STUDIES“ cites the many studies finding success of SCD with a focus on IBD and autism.
Understanding what is Epigenetics and gene expression
Chemical tags shape our epigenome. Chemical tags react to signals from our rapidly changing environment and world (such as diet, toxins in air, water, and food, stress…) and expresses genes by altering the mRNA and protein production. Different genes are active in different cell types. At any one time, some genes are active and others are inactive. The post THE SCIENCE BEHIND FOOD, DISEASE, MICROBIOME discusses much more epigenetics and gene expression (with some cool visuals and videos of what is really going on) if you are interested.
To better understand WHAT EPIGENETICS IS, perhaps the most easy visual demonstration is shown on the last two slides below. Notice how the punctuation variance dramatically changes up the dialogue context, so too with epigenetics. Though epigenetics does not “CHANGE UP” THE DNA, AN EPIGENETIC CHANGE READS THE INFORMATION DIFFERENTLY AND EXPRESSES GENES ACCORDINGLY; that can be beneficial or detrimental to health and disease status.
This study notes that prior studies focusing on gastrointestinal cancers looked to identify individual bacterial species that directly initiate or promote the cancers. Now it is understood that the microbiome influences systemic inflammation and it is the community of microbes that may affect downstream pathways and affect risk of cancer in tissues beyond the gastrointestinal tract. Mechanisms for “functional contributions of the gut microbiota that may influence cancer susceptibility in the broad sense include:
- harvesting otherwise inaccessible nutrients and/or sources of energy from the diet (i.e., fermentation of dietary fibers and resistant starch);
- metabolism of xenobiotics, both potentially beneficial or detrimental (i.e., dietary constituents, drugs, carcinogens, etc.);
- renewal of gut epithelial cells and maintenance of mucosal integrity; and
- affecting immune system development and activity.”
This study also notes the likely link between the microbiome and systemic cancer effects, and that therapeutics could involve microbiome manipulation (here resistant starch is suggested):
“The most novel and relevant recent data describe a role for resistant starch in ameliorating inflammation; the use of resistant starch for optimal bowel health and prevention of colon rectal cancer; and, further, that the systemic effects of resistant starch may be important for the treatment of other forms of cancer, such as breast cancer.”
“Resistant starch represents a diverse range of indigestible starch-based dietary carbohydrates. Resistant starch has been investigated in the past for its effects on bowel health (pH, epithelial thickness, and apoptosis of colorectal cancer cells); reduction in postprandial glycemia; increased insulin sensitivity; and effects on the gut microbiome. This review highlights advances as resistant starch gains clinical relevance as a potential treatment/preventive tool for diseases such as colorectal cancer and diabetes.”
Cancer and the microbiome of specific tissues.
The paper, Metagenomics: A new horizon in cancer research summarizes the recent anaerobic 16S rRNA gene sequencing technology implications for various cancers (Gastric carcinoma, Colorectal Carcinoma, Cervical cancer, Oral carcinoma, Brain cancer, and Skin cancer). This paper noted the significance of the latest gene sequencing technology:
About 16.1% of cancers are associated with microbial infection. Table 1 contains the list of micro-organisms which are susceptible for causing cancer. About 99% of the micro-organisms remain uncultured and cannot be demonstrated fully by conventional laboratory culture based techniques (Qin et al., 2010). [Translation: Given that most of the microbes are anaerobic; those involved in disease process are only now being “seen” through the recent newly developed 16S rRNA gene sequencing technology. “Microbiome” and “disease” only began to publish in papers around 2013 — see the below slide.]
What is metagenomics?
Metagenomics focus is on the genes in the community and how genes might influence each other’s activities in serving collective functions. Relative to cancer, Metagenomics: A new horizon in cancer research explains:
Metagenomics has broadened the scope of targeting microbes responsible for inducing various types of cancers. Metagenomics is an equitable way of identifying and studying micro-organisms within their habitat. In cancer research, this approach has revolutionized the way of identifying, analyzing and targeting the microbial diversity present in the tissue specimens of cancer patients. The genomic analyses of these micro-organisms through next generation sequencing techniques invariably facilitate in recognizing the microbial population in biopsies and their evolutionary relationships with each other. In this review an attempt has been made to generate current metagenomic view on cancer microbiota. Different types of micro-organisms have been found to be linked to various types of cancers, thus, contributing significantly in understanding the disease at molecular level.
Breast Microbiome and Cancer
To learn about the breast microbiome and cancer association, read the post, Breast Microbiome and Cancer Risk Assessment Tool.
A look at Skin Cancer and Microbiome
It is more than moles. The study, Total Nevi, Atypical Nevi, and Melanoma Thickness An Analysis of 566 Patients at 2 US Centers, surprisingly found that most people with melanoma, a deadly kind of skin cancer, have very few moles and those they have are not oddly shaped or colored, nor large in size. The study included 566 patients with melanoma, mean age 57 years. An article on this study is Popular Misconceptions About Skin Cancer Debunked noted:
This doesn’t mean that moles are meaningless. Their presence is considered a strong risk factors for melanoma, and the new study showed that more unusual moles you have, the greater the likelihood was of a worse prognosis melanoma. But the findings do suggest a different public health message: that the absence of moles doesn’t mean you shouldn’t get checked for skin cancer.
The paper, Metagenomics: A new horizon in cancer research explains the skin cancer microbiome:
The skin that acts as the protective barrier of our body from the external environment comprises large pool of diverse class of micro-organisms. Imbalance in the normal microbial population in the skin may give rise to skin neoplasia. The substantial research investigations confirm the explicit role of micro-organisms even in the non-infectious skin diseases, such as atopic dermatitis, rosacea, psoriasis and acne (Paulino et al., 2006 and Till et al., 2000). Gao et al. (2007) used the 16S rRNA sequencing technique for predicting the composition of skin microbiota. Mathieu et al. explored the skin microbiome and conveyed the presence of Corynebacterium, Staphylococcus andPropionibacterium as the dominant skin colonizing taxa ( Mathieu et al., 2013), on the other hand, another investigation of the metagenomic analyses of human skin lesions revealed the skin prevalence of 97% of HPV sequences by employing HTS (Bzhalava and Dillner, 2013). A most significant presence of Merkel Cell Polyomavirus (MCPyV) in an aggressive neuro-endocrine skin cancer has been detected ( Feng et al., 2008 and Shuda et al., 2008) but its co-occurrence in the normal healthy skin surface aroused the questionability of its relatedness towards skin carcinoma ( Foulongne et al., 2010, Schowalter et al., 2010 and Wieland et al., 2009).
Conclusion — CANCER MICROBIOME
Be it linked to origination in the gut microbiome or localized to specific tissue microbiome… It was just a matter of time until researchers linked cancer with microbiome using the new 16S rRNA gene sequencing technology studies.
Last updated: March 23, 2016 at 4:52 am for SEO optimization
In health through awareness,