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World J Stem Cells. Sep 26, 2016; 8(9): 279-287
Published online Sep 26, 2016. doi: 10.4252/wjsc.v8.i9.279
Racial disparity in colorectal cancer: Gut microbiome and cancer stem cells
Sachin Goyal, Pratima Nangia-Makker, Lulu Farhana, Yingjie Yu, Adhip PN Majumdar
Sachin Goyal, Pratima Nangia-Makker, Lulu Farhana, Yingjie Yu, Adhip PN Majumdar, Department of Internal Medicine, John D Dingell VA Medical Center, Detroit, MI 48201, United States
Sachin Goyal, Pratima Nangia-Makker, Lulu Farhana, Yingjie Yu, Adhip PN Majumdar, Department of Internal Medicine, Wayne State University, Detroit, MI 48201, United States
Pratima Nangia-Makker, Adhip PN Majumdar, Karmanos Cancer Institute, Wayne State University School of Medicine, Detroit, MI 48201, United States
Author contributions: Goyal S, Nangia-Makker P and Majumdar APN contributed to conception and design of the study, literature review and analysis, drafting and critical revision and editing, and final approval of the final version; Farhana L and Yu Y contributed to experimental work, literature review and analysis, and final approval of the final version.
Supported by National Institutes of Health, No. 1R21 CA175916; Department of Veteran Affairs, No. I101BX001927; and Metropolitan Detroit Research and Education Fund (MDREF) grants to Dr. Majumdar.
Conflict-of-interest statement: No potential conflicts of interest. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.
Open-Access: This article is an open-access article which was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/
Correspondence to: Adhip PN Majumdar, PhD, Professor of Medicine, Department of Internal Medicine, Wayne State University, 4646 John R, B-4238, Detroit, MI 48201, United States. a.majumdar@wayne.edu
Telephone: +1-313-5764460 Fax: +1-313-5761112
Received: May 27, 2016
Peer-review started: May 27, 2016
First decision: June 17, 2016
Revised: July 12, 2016
Accepted: July 20, 2016
Article in press: July 22, 2016
Published online: September 26, 2016
Abstract

Over the past two decades there has been remarkable progress in cancer diagnosis, treatment and screening. The basic mechanisms leading to pathogenesis of various types of cancers are also understood better and some patients, if diagnosed at a particular stage go on to lead a normal pre-diagnosis life. Despite these achievements, racial disparity in some cancers remains a mystery. The higher incidence, aggressiveness and mortality of breast, prostate and colorectal cancers (CRCs) in African-Americans as compared to Caucasian-Americans are now well documented. The polyp-carcinoma sequence in CRC and easy access to colonic epithelia or colonic epithelial cells through colonoscopy/colonic effluent provides the opportunity to study colonic stem cells early in course of natural history of the disease. With the advent of metagenomic sequencing, uncultivable organisms can now be identified in stool and their numbers correlated with the effects on colonic epithelia. It would be expected that these techniques would revolutionize our understanding of the racial disparity in CRC and pave a way for the same in other cancers as well. Unfortunately, this has not happened. Our understanding of the underlying factors responsible in African-Americans for higher incidence and mortality from colorectal carcinoma remains minimal. In this review, we aim to summarize the available data on role of microbiome and cancer stem cells in racial disparity in CRC. This will provide a platform for further research on this topic.

Keywords: Colorectal cancer, Cancer stem cells, Racial disparity, Microbiome, MiRNA

Core tip: The role of microbial dysbiosis and cancer stem cells (CSCs) in colorectal cancer (CRC) has been studied extensively, however, their implication in racial disparity is not well known. A number of recent studies have shown that different dietary patterns affect gut microbiome. Likewise, dietary patterns also affect intracellular regulatory events which may affect the function of CSCs. Our objective is to consolidate the available data, on the role of gut microbiome and CSCs in racial disparity in CRC, explore a link between them and lay a foundation for further advances.