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OBJECTIVES: Although the rind of a watermelon contains much of health benefiting nutrients, it is much less appreciated by consumers and is often disposed. The purpose of this study was to compare sensory properties of blenderized watermelon (WM) flesh juice with and without rind. METHODS: Twenty-three semi-trained college students (age 26.1 ± 6.0 y, BMI 22.7 ± 3.1 kg/m(2), 18 females and 5 males) participated in the sensory evaluation of blenderized WM flesh juice with and without the rind. Participants were asked to identify the unique sample among three samples in a triangle test. In addition, participants rated color, consistency, smell, flavor, sweetness, mouthfeel, aftertaste, and acceptance of the two samples using a 7-point hedonic scale. Each sample was presented in a 2-ounce clear plastic condiment cup with a randomly assigned number. Panelists were asked to rinse their mouths with water before assessing each sample. The triangle test and hedonic scaling were analyzed by binomial analysis and t-test, respectively. RESULTS: The majority of the panel (21 out of 23 panelists) could distinguish the odd sample from the other samples in the triangle test (P

Background Colorectal cancer is the 2nd leading cause of cancer death in Canada. In rapidly dividing tissues such as the intestine or colon, only long-lived, multipotent, self-renewing tissue stem cells have longevity to accumulate mutations and serve as the cellular origin of cancer. In the small intestine, genetic fate mapping studies have demonstrated that there are at least two principal stem cell pools: actively cycling, crypt base cells expressing Lgr5, and quiescent cells situated above the crypt base. Clevers and colleagues have previously shown that Lgr5-expressing cells can give rise to cancer upon mutation. Interestingly, when Lgr5+ stem cells are selectively “killed”, intestinal integrity remains intact and other stem cells restore homeostasis. To determine whether another stem cell population can give rise to cancer in the colon, we examined whether the atypical homeobox protein Hopx, marks stem cells in the colon and whether these cells can give rise to colon cancer. Aims In the present study, we aim to determine whether Hopx-expressing cells are colonic stem cells that contribute to gut healing and can give rise to colonic tumours following the loss of APC. Methods To determine whether Hopx expressing cells show stemness, we crossed Hopx-CreERT mice to R26-TdTomato reporter mice. We then conducted genetic lineage tracing studies in the colon during homeostasis and following dextran sodium sulphate (DSS)-induced colitis. To test the function of Hopx expressing cells, Hopx-CreERT mice were also crossed to R26DTR mice and treated with diphtheria toxin (DT) following tamoxifen. These mice were then exposed to either normal drinking water or DSS to determine the role of Hopx+ cells in colonic regeneration. To test whether Hopx expressing cells can serve as a cellular origin for colon cancer, Hopx-CreERT mice were crossed to Apcf/f (floxed) mice. Results Consistent with the labeling of a stem cell, following tamoxifen, Hopx+ cells expressing tdTomato expanded to lineage trace full colonic crypts within 7 days, and labelling was persistent for greater than 6 months. Interestingly, ablation of Hopx+ cells with DT did not alter weight, histological damage or survival during normal homeostasis, however, Hopx+ cell ablation in mice treated with DSS resulted in increased histological damage. Surprisingly, loss of APC in Hopx-expressing cells did not induce colonic adenomas even after 8 months following tamoxifen administration. Conclusions These findings prove that Hopx expressing cells identify a novel colonic stem cell pool that is redundant in homeostasis, but in the context of injury, are essential for epithelial regeneration. Interestingly, Hopx+ cells do not have the capacity to give rise to colorectal adenomas upon loss of the APC gene. Funding Agencies CIHR

Background Colorectal cancer (CRC) is the second leading cause of cancer death, with a major risk factor being chronic inflammation. Despite the clear association between inflammation and cancer, the mechanism by which colitis leads to CRC is not well understood. We recently showed that the presence of inflammation does not always correlate with colonic tumorigenesis, as the type of colitis (i.e. colitis-inducing agent) appears to be important for tumor initiation. Aims In this study, we aim to explore the mechanism by which inflammation contributes to the initiation of colitis-associated cancer. We hypothesized that dextran sodium sulfate (DSS)-induced colitis leads to the infiltration of a specific immune cell type that is associated with colonic tumorigenesis. Methods To generate tamoxifen-inducible Cre transgenic mice that allow for Dclk1+ cell lineage tracing and cell-specific knock-out of the tumor suppressor adenomatous polyposis coli (APC), we first crossed our transgenic Dclk1CreERT2 mice to both ROSA26tdTomato and APCfl/fl mice (Dclk1/APCfl/fl). Following Tamoxifen induction, mice were treated with the colitis-inducing agents DSS, trinitrobenzene sulfonic acid (TNBS), oxazolone, or Citrobacter rodentium. The tumor studies were repeated using azoxymethane (AOM)-DSS induced colitis-associated cancer model. Results Treatment with any of the four colitis-inducing agents (DSS, TNBS, oxazolone, or C. rodentium) induced colonic inflammation as detected by increased myeloperoxidase (MPO) activity and histologic analysis. Interestingly, DSS administration led to colonic tumors, whereas TNBS, oxazolone, or C. rodentium did not, even up to 52 weeks following colitis induction. FACS analysis of immune cells in the colon revealed no difference in the number of T or B cells in mice treated with any of the colitis-inducing agents. We did, however, detect significantly increased levels of Ly6G+ neutrophils and F4/80+ macrophages in DSS-treated mice compared to mice in any of the other three models of colitis. Consistent with this myeloid cell infiltration, significantly upregulated protein levels of G-CSF, IL-6, TNF-α, and CXCL1 were detected in DSS-treated mice compared to the other three models of colitis. IL-1α, IL-1β, IL-4, IL-10, and TGF-β levels were unchanged. Conclusions Our data suggest that infiltration of Ly6G+ neutrophils and pro-inflammatory F4/80+ macrophages, unique to DSS-induced colitis, contributes to colonic tumor formation. These data demonstrate that specific immune cell types, rather than the presence of colonic inflammation, play a critical role in the initiation of colitis-associated CRC. Funding Agencies CAG, CIHR

BACKGROUND: Colorectal cancer (CRC) is the second leading cause of cancer death in Canada, with the major risk factor being chronic inflammation. As such, patients with inflammatory bowel disease (IBD) are at an increased risk of CRC. Despite the clear association between inflammation and cancer, the mechanism by which colitis leads to CRC is still not well understood. Our recent work has focused on a colonic epithelial cell known as the tuft cell that uniquely expresses the protein doublecortin-like kinase 1 (Dclk1). Using Cre-dependent lineage tracing of Dclk1-expressing cells, we showed that Dclk1 labels long-lived quiescent cells in the colon that serve as a cellular origin of CRC upon colonic inflammation. AIMS: In this study, we aim to explore the mechanism by which inflammation contributes to tuft cell cancer initiation. We hypothesized that colonic inflammatory insult leads to dedifferentiation of Dclk1+ tuft cells to a stem cell state susceptible to tumor initiation. METHODS: To generate tamoxifen-inducible Cre transgenic mice that allow for Dclk1(+) cell lineage tracing and cell-specific knock-out of the tumor suppressor adenomatous polyposis coli (APC), we first crossed our transgenic Dclk1-CreER(T2) mice to both ROSA26-tdTomato and APC(fl/fl) mice (Dclk1/APC(fl/fl)). To examine the role of dedifferentiation in colonic tumor initiation, these mice were further crossed to Lgr5-DTR-eGFP mice (Lgr5(DTR);Dclk1/APC(fl/fl)). These mice were given tamoxifen and DSS in order to induce tumorigenesis. Mice were administered diphtheria toxin (DT) for six weeks post DSS injury to ablate Lgr5-expressing cells and were compared to Lgr5(DTR)-negative control mice (Dclk1/APC(fl/fl)). RESULTS: Reverse transcription polymerase chain reaction (RT-PCR) analysis of mRNA levels revealed significantly reduced Lgr5, and increased RSPO1 and RSPO3 levels in colonic tissues of DSS-administered mice. Ablation of Lgr5(+) cells post DSS-colitis significantly reduced the number of colonic tumors in our Dclk1/APC(fl/fl) mouse model, with no significant difference in tumor size. Lgr5-expressing cells were readily seen throughout colonic tumors arising from Dclk1(+) cells. Interestingly, two weeks post DSS-induced colitis, rare Dclk1(+) cells that co-expressed Lgr5 were also detected. CONCLUSIONS: Our data prove that upon DSS-induced colonic injury, Dclk1(+) tuft cells express the stem cell marker Lgr5 prior to initiation of colonic tumorigenesis. These data suggest that dedifferentiation of Dclk1(+) cells plays an important role in colitis-associated CRC and provide insight into the molecular mechanism by which Dclk1-derived colonic tumors arise. FUNDING AGENCIES: CAG, CIHRCRS