Butyrate-rich Colonic Microenvironment Is a Relevant Selection Factor for Metabolically Adapted Tumor Cells

Abstract

The short chain fatty acid (SCFA) buyrate is a product of colonic fermentation of dietary fibers. It is the main source of energy for normal colonocytes, but cannot be metabolized by most tumor cells. Butyrate also functions as a histone deacetylase (HDAC) inhibitor to control cell proliferation and apoptosis. In consequence, butyrate and its derived drugs are used in cancer therapy. Here we show that aggressive tumor cells that retain the capacity of metabolizing butyrate are positively selected in their microenvironment. In the mouse xenograft model, butyrate-preselected human colon cancer cells gave rise to subcutaneous tumors that grew faster and were more angiogenic than those derived from untreated cells. Similarly, butyrate-preselected cells demonstrated a significant increase in rates of homing to the lung after intravenous injection. Our data showed that butyrate regulates the expression of VEGF and its receptor KDR at the transcriptional level potentially through FoxM1, resulting in the generation of a functional VEGF:KDR autocrine growth loop. Cells selected by chronic exposure to butyrate express higher levels of MMP2, MMP9, ␣2 and ␣3 integrins, and lower levels of E-cadherin, a marker for epithelial to mesenchymal transition. The orthotopic model of colon cancer showed that cells preselected by butyrate are able to colonize the animals locally and at distant organs, whereas control cells can only generate a local tumor in the cecum. Together our data shows that a butyrate-rich microenvironment may select for tumor cells that are able to metabolize butyrate, which are also phenotypically more aggressive.Short chain fatty acids are the final product of bacterial fermentation of dietary fibers (1). Butyrate, a 4-carbon fatty acid, is the main energy source for normal colonocytes (2, 3), which are found in high concentrations in the colonic lumen. It is also thought to be responsible for colorectal cancer prevention, as butyrate can also function as a histone deacetylase (HDAC) 4 inhibitor to inhibit cell proliferation and induce apoptosis of cancer cells (4 -6); probably because of this, cancer cells are normally unable to metabolize butyrate.The anti-tumor effects of butyrate were described in studies using colorectal cancer cell lines, in which butyrate inhibits growth, and induces differentiation and apoptosis (7). In other studies butyrate was able to inhibit tumor growth in vivo in murine models (8, 9). Despite these findings, there is an unresolved paradox concerning the putative protective role of butyrate in colon cancer, colorectal cancers still develop and grow despite the high concentrations of butyrate in the colon. Furthermore, several studies have now shown that butyrate-resistant cells may be selected and give rise to more aggressive cancers (8,10,11). The mechanisms by which cancer cells develop resistance to butyrate and progress remain unknown.Here, we demonstrate that chronic exposure of colon cancer cells to butyrate may result in the selection of more aggressive clones. Our data ...

Butyrate Histone Deacetylase Inhibitors

“…A significant source in the diet comes from dairy products (such as Greek feta cheese) containing lamb rennet. 52,53 However, n -butyric acid (butyrate) is also endogenously made in the human body by anaerobic bacterial fermentation of carbohydrates (derived from dietary fiber) in the colon, 54–56 but in addition to being a part of the metabolic fatty acid fuel cycle, 57,58 butyrate is also capable of inducing growth arrest in a variety of normal cell types and senescence-like phenotypes in gynecological cancer cells, 59,60 inhibiting DNA synthesis and cell growth in colonic tumor cell lines, 61–64 suppressing hTERT mRNA expression and telomerase activity in human prostate cancer cells, 65 and inducing stem cell differentiation 66–71 and apoptosis by DNA fragmentation. 72 It regulates gene expression by inhibiting HDACs, 73,74 enhances memory recovery and formation in mice, 75 stimulates neurogenesis in the ischemic brain, 70,76,77 promotes osteoblast formation, 78 selectively blocks cell replication in transformed cells (compared to healthy cells), 79–81 and can prevent and treat diet-induced obesity and insulin resistance in mouse models of obesity, 82 as well as stimulate fetal hemoglobin expression in individuals with hematologic diseases such as the thalassemias and sickle-cell disease, 83–85 in addition to a multitude of other biochemical effects in vivo .…”

The Vitro Fermentation of Six Functional Oligosaccharides by Clostridium butyricum TK2 and Clostridium butyricum CB8

“…Furthermore, in vitro studies as well as animal studies indicate that butyrate may reduce risk factors of gut inflammation (Roediger, 1990;Cummings and Englyst, 1991;Segain et al, 2000;Galvez et al, 2005). It also has been observed to reverse the resistance of colorectal cancer cells to apoptosis (Caderni et al, 1998;Leng et al, 2001;Brouns et al, 2002;Hinnebusch et al, 2002;Blottiere et al, 2003;Kien et al, 2006;McOrist et al, 2008;Serpa et al, 2010).…”

“…The SCFA (acetate, propionate and butyrate) have an beneficial influence on colonic health (Mortensen and Clausen, 1996;Scheppach et al, 2001;Williams et al, 2001;Wong et al, 2006;Macfarlane and Macfarlane, 2012). In particular butyrate is the prime energy substrates for the colonic mucosa and has an effect on immune function (Roediger, 1980;Fleming and Floch, 1986;Wong et al, 2006;McOrist et al, 2008;Serpa et al, 2010). Furthermore, in vitro studies as well as animal studies indicate that butyrate may reduce risk factors of gut inflammation (Roediger, 1990;Cummings and Englyst, 1991;Segain et al, 2000;Galvez et al, 2005).…”

Unravelling the role of fatty acid metabolism in cancer through the FOXO3-FOXM1 axis

“…Conversely, incubation with the omega-3 FA eicosapentaenoic acid (EPA), but not DHA, causes an increase in FOXO3 phosphorylation and hence inactivation in murine C2C12 myotubes (Kamolrat and Gray, 2013). In addition, in human colon cancer cells, the expression of the potent oncogene FOXM1 is increased in presence of the short chain FA butyrate, which is a product of colonic fermentation of dietary fibres (Serpa et al, 2010).…”