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Differences in gut microbiota and serum Trimethylamine N-oxide (TMAO) levels in patients with colorectal cancer with a small, nested case-control study

Jian Huang1, Xiaohua Chen1, Qinglian Zhong1*

[1] Department of Gastroenterology, The Eighth Affiliated Hospital, Sun Yat-sen University, Shenzhen, Guangdong 518033, China


The dysbiosis of the gut microbiota caused by drug metabolism and diets may influence the gastrointestinal (GI) barrier and their ability for normal attachment and further immunity system, which all could be associated with the medical efficacy of colorectal cancer (CRC) during chemotherapy.

This study aims to investigate Trimethylamine N-oxide (TMAO), a gastrointestinal product readily entering the bloodstream, as a potential risk factor for various diseases, including CRC.

To investigate the relationship between gut microbiota dysbiosis and carcinogenesis in CRC patients, we analyzed taxonomic alterations in the gut microbiota of 77 subjects, including 36 CRC patients and 41 normal controls. We collected samples of the participants’ microbiome from their fecal material and utilized 16S rRNA sequencing to identify the microbial composition. Additionally, to predict the functions of the GI microbiota, Phylogenetic Investigation of Communities by Reconstructing Unobserved States (PICRUSt) was employed. This could serve as a promising biomarker for colorectal cancer. Moreover, the serum level of TMAO between the CRC and healthy controls was also compared, and it was observed that the intestinal microbiome was changed in CRC patients; however, the serum level of TMAO was not correlated with the progression of CRC.

In conclusion, in the present study, instead of relying solely on TMAO, which is a convenient clinical test, we focused on the treatment of CRC by emphasizing the modification of the intestinal microbiome.

Keywords: CRC, Intestinal microbiome, TMAO, 16s rRNA, PICRUSt

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