Mapping of Gut Microbiome Secretome in CRC

By: Putri Intan Hafizah Megat Mohd Azlan (putrimegatazlan@gmail.com)

Human gut especially the large intestine, hosts nearly trillions of microbes with thousands of different species (Dulal & Keku 2014; Neu & Rushing 2011). These microbes provide mutual benefits to human by aiding in nutrient metabolism, xenobiotic detoxification, gut epithelial integrity maintenance and protection against pathogens (Chow, J. et al. 2010; Sun & Chang 2014). However, a slight change in the microbial community known as dysbiosis may turn the well-maintained homeostasis into a tumor microenvironment. (Schwabe & Jobin 2013). Dysbiosis of the gut microbiome has been reported as one of the risk factors for colorectal cancer (CRC). In order to elucidate further on the relationship between gut microbiome and CRC manifestation, a proper representative sample of the colonic microbiota has to be carefully chosen. Stool is an interesting sample to study human gut microbiome as the collection is non-invasive and most importantly able to provide information on host-microbe relationship (Eckburg, P.B. et al. 2005; Lichtman, J.S. et al. 2013; Verberkmoes, N.C. et al. 2008). Microbes are known to secret substantial amount of proteins into the extracellular environment that may mediate hostbacterial interactions and therefore, the study on these secreted protein or better known as secretome enables us to identify the constituents of the microbial community, activity expression and host response (Lichtman, J.S. et al. 2013). A comprehensive proteomic profiling of these proteins may facilitate the identification of potential biomarkers that are  responsible for for cancer progression such as growth factors, cytokines, proteases and others (Barderas, R. et al. 2013). To date, the study on secretome of the gut microbiome in CRC by using stool samples are yet to be reported. Thus, this study is carried out to elucidate the possible relationship of the secreted proteins and the etiology of CRC. Currently, we have analyzed six secreted protein samples (three healthy and three CRC) extracted from the fecal materials  by using the SWATH-MS analysis. We have found two human proteins that were expressed significantly higher in the healthy as compared to the CRC individuals. However, this is just a preliminary result and further analysis is needed to confirm the finding.

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