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The intrinsic role of endogenous IL-17A in spontaneous intestinal tumorigenesis has not been addressed previously to our knowledge. Ablation of IL-17A significantly reduced tumor development in mice bearing a heterozygote mutation in the adenomatous polyposis coli (APC) gene ([Apc.sup.Min/+] mice). There was also a decrease in inflammatory cytokines and proinflammatory mediators, reduced infiltration of lymphocytes including T cells, and preservation of intestinal architecture and the presence of APC protein in intestinal epithelial cells. Interestingly, IL-17A ablation also corrected immunological abnormalities such as splenomegaly and thymic atrophy in [Apc.sub.Min/+] mice. CD4 T cells from [Apc.sub.Min/+] mice showed hyperproliferative potential in vitro and in vivo and increased levels of IL-17A and IL-10. The effector CD4 T cells from [Apc.sup.Min/+] mice were more resistant to regulatory T cell-mediated suppression. Finally, these CD4 T cells induced colitis in immunodeficient mice upon adoptive transfer, whereas the ablation of IL-17A in CD4 T cells in [Apc.sup.Min/+] mice completely abolished this pathogenic potential in vivo. Taken together, our results show that CD4 T cell-derived IL-17A promotes spontaneous intestinal tumorigenesis with altered functions of CD4 T cells in [Apc.sup.Min/+] mice. inflammation | T cells | colon cancer www.pnas.org/cgi/doi/10.1073/pnas.0912675107

Although cancer is a disease with genetic and epigenetic origins, the possible effects of reprogramming by defined factors remain to be fully understood. We studied the effects of the induction or inhibition of cancer-related genes and immature status-related genes whose alterations have been reported in gastrointestinal cancer cells. Retroviral-mediated introduction of induced pluripotent stem (iPS) cell genes was necessary for inducing the expression of immature status-related proteins, including Nanog, Ssea4, Tra-1-60, and Tra-1-80 in esophageal, stomach, colorectal, liver, pancreatic, and cholangiocellular cancer cells. Induced cells, but not parental cells, possessed the potential to express morphological patterns of ectoderm, mesoderm, and endoderm, which was supported by epigenetic studies, indicating methylation of DNA strands and the histone H3 protein at lysine 4 in promoter regions of pluripotency-associated genes such as NANOG. In in vitro analysis induced cells showed slow proliferation and were sensitized to differentiation-inducing treatment, and in vivo tumorigenesis was reduced in NOD/SCID mice. This study demonstrated that pluripotency was manifested in induced cells, and that the induced pluripotent cancer (iPC) cells were distinct from natural cancer cells with regard to their sensitivity to differentiation-inducing treatment. Retroviral-mediated introduction of iPC cells confers higher sensitivity to chemotherapeutic agents and differentiation-inducing treatment. cancer stern ceils | epigenetics | pluripotent stem cells | embryonic stem ceils | differentiation www.pnas.org/cgi/doi/10.1073/pnas.0912407107

Gastrointestinal (GI) neoplasms are among many manifestations of the genetic disease neurofibromatosis type 1 (NF1). However, the physiological and pathological functions of the Nf1 gene in the GI system have not been fully studied, possibly because of a lack of mouse models. In this study, we generated conditional knockout mice with Nf1 deficiency in the GI tract. These mice develop gastric epithelial hyperplasia and inflammation together with increased cell proliferation and apoptosis. The gastric phenotypes observed in these mutant mice seem to be the consequence of loss of Nf1 in gastric fibroblasts, resulting in paracrine hyperactivation of the ERK pathway in the gastric epithelium. These mice provide a useful model to study the pathogenesis of GI lesions in a subset of patients with NF1 and to investigate the role of the Nf1 gene in the development of GI neoplasms. Islet1-Cre doi: 10.1152/ajpgi.00007.2009

Epidemiological studies suggest that low dietary folate increases risk for intestinal neoplasia. We recently developed a unique tumor model in which mice fed low dietary folate developed DNA damage and intestinal tumors. To identify additional mechanisms by which reduced folate intake contributes to tumor formation in this model, we characterized gene expression signatures in tumors. A total of 175 probe sets had altered expression, with the majority (173) showing increased expression compared with normal intestine. Functional categorization revealed that most genes were involved in cancer (51 genes) or cell death (37 genes); 31 genes appeared in both categories. Because apoptosis resistance is a hallmark of neoplasia, we assessed apoptosis in normal intestine of mice fed control (CD) and low-folate diets (FD); apoptosis was reduced in FD normal intestine compared with CD intestine by active caspase-3 expression (P = 0.027) and caspase-3/7 activities (P = 0.059). We selected candidate genes with antiapoptotic properties that had increased expression in tumor microarrays, CD44, and gelsolin and confirmed these increases at the mRNA and protein levels. CD44 and gelsolin protein also increased in mice fed the FD compared with the CD, normal intestine. Bc1-2-like 1:Bc1-2-antagonist/killer 1 mRNA ratios tended to be greater in FD than in CD normal intestine (P = 0.056). In conclusion, tumors induced by low dietary folate exhibited gene expression profiles that are characteristic of disrupted apoptosis. Folate depletion in normal intestine may trigger neoplasia through increased DNA damage and defective apoptosis; upregulation of CD44 and gelsolin, and the mitochondrial apoptotic pathway are implicated.

Ectopic expression of the gastrin-releasing peptide (GRP) receptor (GRP-R) occurs frequently in human malignancies of the gastrointestinal tract. Owing to paracrine and autocrine interaction with its specific high-affinity ligand GRP, tumor cell proliferation, migration, and invasion might ensue. Here we provide the first insights regarding molecular mechanisms of GRP-R regulation in gastrointestinal cancer cells. We identified by EMSA and chromatin immunoprecipitation assays two cAMP response element (CRE) binding sites that recruited transcription factor CRE binding protein (CREB) to the human GRP-R promoter. Transfection studies with a wild-type human GRP-R promoter reporter and corresponding CRE mutants showed that both CRE sites are critical for basal transcriptional activation in gastrointestinal cancer cells. Forced expression of cAMP-dependent effectors CREB and PKA resulted in robust upregulation of human GRP-R transcriptional activity, and this overexpression strictly required intact wild-type CRE sites. Direct cAMP stimulation with forskolin resulted in enhanced human GRP-R promoter activity only in HuTu-80 cells, but not in Caco-2 cells, coinciding with forskolin-induced CREB phosphorylation occurring only in HuTu-80 but not Caco-2 cells. In summary, CREB is a critical regulator of human GRP-R expression in gastrointestinal cancer and might be activated through different upstream intracellular pathways. regulatory peptide; bombesin; gastrointestinal cancer; cyclic AMP response element

Gastrointestinal cancers account for 20% of all cancer incidences worldwide. Colorectal cancer is the second most common cause of all cancer-related mortality and is increasing in Western societies. Infection and inflammation contribute to 15-20% of all malignancies, and are predisposing risk factors for gastrointestinal cancers. Helicobacter pylori infection is commonly associated with gastric cancers, and chronic inflammation increases the risk of colorectal cancer by 1% per year. Micronutrient status and common genetic variations in human populations modify risk for gastrointestinal cancer. Chronic inflammation promotes carcinogenesis by inducing gene mutations, inhibiting apoptosis, and stimulating angiogenesis and cell proliferation. Inflammation also induces epigenetic alterations that are associated with cancer development. Two key genes in the inflammatory process, cyclooxygenase-2 (COX-2) and nuclear factor-kappa B (NF-[kappa]B), provide a mechanistic link between inflammation and cancer and are targets for chemoprevention. Dietary components, and human genetic variation that affects nutrient utilization, can directly modify inflammatory processes and/or suppress genomic alterations that are the molecular antecedents of cancers. The present report focuses on the convergence of genetic, nutritional, and inflammatory factors in the initiation and progression of gastrointestinal cancers, and the emerging dietary strategies for cancer prevention. Key words: gastrointestinal, cancer, irritable bowel disease, celiac disease, Helicobacter pylori, inflammation. doi: 10.1301/nr.2007.dec.S157-S 166

The development of intestinal cancer involves complex genetic and epigenetic alterations in the intestinal mucosa. The principal signaling pathway responsible for the initiation of tumor formation, the APC-[beta]-catenin-TCF4 pathway, regulates both cell proliferation and colonic cell differentiation, but many other intrinsic and extrinsic signals also modulate these cell maturation pathways. The challenge is to understand how signaling and cell maturation are also modulated by nutritional agents. Through gene expression profiling, we have gained insight into the mechanisms by which short chain fatty acids regulate these pathways and the differences in response of gene programs, and of the specific regulation of the c-myc gene, to physiological regulators of intestinal cell maturation, such as butyrate, compared with pharmacological regulators such as the nonsteroidal antiinflammatory drug sulindac. Moreover, we used a combination of gene expression profiling of the response of cells in culture to sulindac and the response of the human mucosa in subjects treated with sulindac for 1 month, coupled with a mouse genetic model approach, to identify the cyclin dependent kinase inhibitor [p21.sup.WAF1/Cip1] as an important suppressor of Apc-initiated intestinal tumor formation and a necessary component for tumor inhibition by sulindac. Finally, the mucous barrier, secreted by intestinal goblet cells, is the interface between the luminal contents and the intestinal mucosa. We generated a mouse genetic model with a targeted inactivation of the Muc2 gene that encodes the major intestinal mucin. These mice have no recognizable goblet cells due to the failure of cells to synthesize and store mucin. This leads to perturbations in intestinal crypt architecture, increased cellular proliferation and rates of cell migration, decreased apoptosis and development of adenomas and adenocarcinomas in the small and large intestine and the rectum. J. Nutr. 132: 3804S-3808S, 2002. KEY WORDS: * intestinal cancer * gene expression profiling * mouse genetic models * mucin * cell maturation

Loss of function of the adenomatous polyposis coil (APC)/Apc tumor suppressor gene occurs early in the etiology of intestinal cancer in mammals. In human colonic tumors, genomic instability is proposed to be associated with tumor initiation by inducing loss of APC function. We have used a mouse model of inherited intestinal cancer ([Apc.sup.Min]/+, Min/+) to analyze the earliest stages of tumorigenesis in this organ. We find that tumors from C57BL/6 Min/+ mice have a stable karyotype and stable microsatellites. In contrast to previous claims, we find that homozygosity for the Min allele of Apc in tumors can proceed by homologous somatic recombination. Further, our analysis of early, benign human colorectal adenomas failed to reveal any evidence for generalized chromosomal or microsatellite instability. These results cast doubt on the hypothesis that either of these forms of genomic instability is necessary for the initial development of colorectal adenomas. We contrast our analysis of autochthonous primary tumors to other studies involving xenografts or cultured cells.

LKB1 kinase activity loss in Peutz-Jeghers syndrome (PJS), a rare autosomal dominant disease involving mucocutaneous pigmentation and gastrointestinal hamartomatous polyposis with high risk of certain cancers, is discussed with the presentation of evidence for allelic and locus heterogeneity. The screening in nine PJS families of various national origins for LKB1 mutations and the finding of seven novel mutations are covered.

The human FHIT gene which belongs to the histidine triad gene family and encodes a protein with 69% likeness to an S. pombe enzyme, diadenosine 5',5''' P1, P4-tetraphosphate asymmetrical hydrolase, was detected. The FHIT locus contains 10 exons spread over at least 500 kb, with three 5' untranslated exons contromeric to the renal carcinoma. Defective transcripts of the FHIT locus were discovered in about half of esophageal, stomach and colon cancer cells.

An understanding the genetic basis for hereditary forms of colon cancer should lead to a better understanding of all types of colon cancers. Hereditary forms of polyposis and nonpolyposis syndromes account for as many as 11% of the approximately 160,000 new cases of colon cancer diagnosed in the US every year. Familial adenomatous, the most common form of adenomatous polyposis syndrome, has an autosomal dominant mode of inheritance. A genetic marker for those at risk for this and other forms of inheritable colon cancer, APC, has been located. People with a family history of the adenomatous or Gardner's syndrome should be screened every two years, beginning at age twelve. Other autosomal inherited colon cancers include Peutz-Jeghers syndrome, juvenile polyposis and Cowden's disease, all hamartomatous polyposis syndromes, and hereditary nonpolyposis colorectal cancers.

The intestinal tumors of B6-Min/+ mice, a mutant strain that develops multiple intestinal adenomas along the duodenal-to-colonic axis (DCA), were studied as to their cellular differentiation. Molecular markers specific for enterocytes, enteroendocrine, goblet and Paneth cells showed that a given tumor contains all cell types as well as undifferentiated cells, and expression of gene products by the cells was appropriate for the region on the DCA. These results indicate that adenomasmay each arise from single, mutated, multipotent stem cells in the intestinal crypts.

Familial juvenile polyposis is an autosomal dominant disease characterized by a predisposition to hamartomatous polyps and gastrointestinal cancer. Here it is shown that a subset of juvenile polyposis families carry germ line mutations in the gene SMAD4 (also known as DPC4), located on chromosome 18q21.1, that encodes a critical cytoplasmic mediator in the transforming growth factor-Β signaling pathway. The mutant SMAD4 proteins are predicted to be truncated at the carboxyl-terminus and lack sequences required for normal function. These results confirm an important role for SMAD4 in the development of gastrointestinal tumors., Familial juvenile polyposis (JP) is an autosomal dominant disease in which individuals are predisposed to hamartomatous polyps and gastrointestinal cancer. Gastrointestinal malignancy develops in 9 to 68% of JP patients [...]

A remarkable instability at simple repeated sequences characterizes gastrointestinal cancer of the microsatellite mutator phenotype (MMP). Mutations in the DNA mismatch repair gene family underlie the MMP, a landmark for hereditary nonpolyposis colorectal cancer. These tumors define a distinctive pathway for carcinogenesis because they display a particular spectrum of mutated cancer genes containing target repeats for mismatch repair deficiency. One such gene is BAX, a proapoptotic member of the Bcl-2 family of proteins, which plays a key role in programmed cell death. More than half of colon and gastric cancers of the MMP contain BAX frameshifts in a [(G).sub.8] mononucleotide tract. However, the functional significance of these mutations in tumor progression has not been established. Here we show that inactivation of the wild-type BAX allele by de novo frameshift mutations confers a strong advantage during tumor clonal evolution. Tumor subclones with only mutant alleles frequently appeared after inoculation into nude mice of single-cell clones of colon tumor cell lines with normal alleles. In contrast, no clones of BAX-expressing cells were found after inoculation of homozygous cell clones without wild-type BAX. These results support the interpretation that BAX inactivation contributes to tumor progression by providing a survival advantage. In this context, survival analyses show that BAX mutations are indicators of poor prognosis for both colon and gastric cancer of the MMP.