Fucosylation Deficiency in Mice Leads to Colitis and Adenocarcinoma

Abstract

Background & Aims De novo synthesis of GDP-fucose, a substrate for fucosylglycans, requires sequential reactions mediated by GDP-mannose 4,6-dehydratase (GMDS) and GDP-4-keto-6-deoxymannose 3,5-epimerase-4-reductase (FX or TSTA3). GMDS deletions and mutations are found in 6%–13% of colorectal cancers; these mostly affect ascending and transverse colon. We investigated whether lack of fucosylation consequent to loss of GDP-fucose synthesis contributes to colon carcinogenesis. Methods FX deficiency and GMDS deletion produce the same biochemical phenotype of GDP-fucose deficiency. We studied a mouse model of fucosylation deficiency (Fx–/– mice) and mice with the full-length Fx gene (controls). Mice were placed on standard chow or fucose-containing diet (equivalent to a control fucosylglycan phenotype). Colon tissues were collected and analyzed histologically or by ELISAs to measure cytokine levels; T cells were also collected and analyzed. Fecal samples were analyzed by 16s rRNA sequencing. Mucosal barrier function was measured by uptake of fluorescent dextran. We transplanted bone marrow cells from Fx–/– or control mice (Ly5.2) into irradiated 8-week old Fx–/– or control mice (Ly5.1). We performed immunohistochemical analyses for expression of Notch and the hes family bHLH transcription factor (HES1) in colon tissues from mice and a panel of 60 human colorectal cancer specimens (27 left-sided, 33 right-sided). Results Fx–/– mice developed colitis and serrated-like lesions. The intestinal pathology of Fx–/– mice was reversed by addition of fucose to the diet, which restored fucosylation via a salvage pathway. In the absence of fucosylation, dysplasia appeared and progressed to adenocarcinoma in up to 40% of mice, affecting mainly the right colon and cecum. Notch was not activated in Fx–/– mice fed standard chow, leading to decreased expression of its target Hes1. Fucosylation deficiency altered the composition of the fecal microbiota, reduced mucosal barrier function and altered epithelial proliferation marked by Ki67. Fx–/– mice receiving control bone marrow cells had intestinal inflammation and dysplasia, and reduced expression of cytokines produced by cytotoxic T cells. Human sessile serrated adenomas and right-sided colorectal tumors with epigenetic loss of MLH1 had lost or had lower levels of HES1 than other colorectal tumor types or nontumor tissues. Conclusions In mice, fucosylation deficiency leads to colitis and adenocarcinoma, loss of Notch activation, and downregulation of Hes1. HES1 loss correlates with development of human right-sided colorectal tumors with epigenetic loss of MLH1. These findings indicate that carcinogenesis in a subset of colon cancer is consequent to a molecular mechanism driven by fucosylation deficiency and/or HES1-loss.

Novel insights into microbiome in colitis and colorectal cancer

“…Consistent with the role of Notch in regulating epithelial cell lineage commitment, Fx -/- mice show goblet cell expansion and aberrant crypt proliferation in the colon (12). Notably, Fx -/- mice sequentially developed colitis, dysplasia and adenocarcinoma, which can be prevented by antibiotic treatment (12). Similarly, mice with IEC-specific deletion of the IBD susceptibility gene Ptpn11 exhibit impaired goblet cell differentiation in the colon and dysbiotic microbiota which drive spontaneous colitis development (13).…”

“…Disruption of intestinal epithelial homeostasis leads to colitis and/or tumorigenesis which can be enhanced by microbiota. For example, mice with fucosylation deficiency ( Fx -/- ) display loss of Notch activation and downregulation of the Notch target gene Hes1 in the colonic epithelium, accompanied by a progressive increase in gut epithelial permeability (12). Consistent with the role of Notch in regulating epithelial cell lineage commitment, Fx -/- mice show goblet cell expansion and aberrant crypt proliferation in the colon (12).…”

“…For example, mice with fucosylation deficiency ( Fx -/- ) display loss of Notch activation and downregulation of the Notch target gene Hes1 in the colonic epithelium, accompanied by a progressive increase in gut epithelial permeability (12). Consistent with the role of Notch in regulating epithelial cell lineage commitment, Fx -/- mice show goblet cell expansion and aberrant crypt proliferation in the colon (12). Notably, Fx -/- mice sequentially developed colitis, dysplasia and adenocarcinoma, which can be prevented by antibiotic treatment (12).…”

Selectin Ligands Sialyl-Lewis a and Sialyl-Lewis x in Gastrointestinal Cancers

“…A general loss of the fucosylation potential has been reported in fact in up to 13% of colorectal cancers due to mutations of an enzyme involved in the biosynthesis of GDP-Fuc [86,87], the mandatory donor of fucose in all fucosyltransferase-catalyzed reactions. Such mutation and the consequent loss of fucosylation was very recently reported to enhance inflammation and tumors in the mouse [88]. On the other side, a general increase of fucosylation was also reported in colorectal cancer, as suggested by the binding of Aleuria aurantia lectin [89], that preferentially recognizes fucose α1,2/3/6 linked to lactosamine units [90].…”

Marine Lectins DlFBL and HddSBL Fused with Soluble Coxsackie-Adenovirus Receptor Facilitate Adenovirus Infection in Cancer Cells BUT Have Different Effects on Cell Survival

“…On the contrary, fucosylation deficiency led to adenocarcinoma in mice [24], and decreased core-fucosylation has been shown to be clinically associated with malignancy of gastric cancer [25]. Meanwhile, increased sialylation was often associated with poor prognosis in cancer patients [13].…”