Publications by authors named "Robert T Cormier"

17 Publications

  • Page 1 of 1

Role of ion channels in gastrointestinal cancer.

World J Gastroenterol 2019 Oct;25(38):5732-5772

Department of Biomedical Sciences, University of Minnesota Medical School, Duluth, MN 55812, United States.

In their seminal papers Hanahan and Weinberg described oncogenic processes a normal cell undergoes to be transformed into a cancer cell. The functions of ion channels in the gastrointestinal (GI) tract influence a variety of cellular processes, many of which overlap with these hallmarks of cancer. In this review we focus on the roles of the calcium (Ca), sodium (Na), potassium (K), chloride (Cl) and zinc (Zn) transporters in GI cancer, with a special emphasis on the roles of the KCNQ1 K channel and CFTR Cl channel in colorectal cancer (CRC). Ca is a ubiquitous second messenger, serving as a signaling molecule for a variety of cellular processes such as control of the cell cycle, apoptosis, and migration. Various members of the TRP superfamily, including TRPM8, TRPM7, TRPM6 and TRPM2, have been implicated in GI cancers, especially through overexpression in pancreatic adenocarcinomas and down-regulation in colon cancer. Voltage-gated sodium channels (VGSCs) are classically associated with the initiation and conduction of action potentials in electrically excitable cells such as neurons and muscle cells. The VGSC Na1.5 is abundantly expressed in human colorectal CRC cell lines as well as being highly expressed in primary CRC samples. Studies have demonstrated that conductance through Na1.5 contributes significantly to CRC cell invasiveness and cancer progression. Zn transporters of the ZIP/SLC39A and ZnT/SLC30A families are dysregulated in all major GI organ cancers, in particular, ZIP4 up-regulation in pancreatic cancer (PC). More than 70 K channel genes, clustered in four families, are found expressed in the GI tract, where they regulate a range of cellular processes, including gastrin secretion in the stomach and anion secretion and fluid balance in the intestinal tract. Several distinct types of K channels are found dysregulated in the GI tract. Notable are hERG1 upregulation in PC, gastric cancer (GC) and CRC, leading to enhanced cancer angiogenesis and invasion, and KCNQ1 down-regulation in CRC, where KCNQ1 expression is associated with enhanced disease-free survival in stage II, III, and IV disease. Cl channels are critical for a range of cellular and tissue processes in the GI tract, especially fluid balance in the colon. Most notable is CFTR, whose deficiency leads to mucus blockage, microbial dysbiosis and inflammation in the intestinal tract. CFTR is a tumor suppressor in several GI cancers. Cystic fibrosis patients are at a significant risk for CRC and low levels of CFTR expression are associated with poor overall disease-free survival in sporadic CRC. Two other classes of chloride channels that are dysregulated in GI cancers are the chloride intracellular channels (CLIC1, 3 & 4) and the chloride channel accessory proteins (CLCA1,2,4). CLIC1 & 4 are upregulated in PC, GC, gallbladder cancer, and CRC, while the CLCA proteins have been reported to be down-regulated in CRC. In summary, it is clear, from the diverse influences of ion channels, that their aberrant expression and/or activity can contribute to malignant transformation and tumor progression. Further, because ion channels are often localized to the plasma membrane and subject to multiple layers of regulation, they represent promising clinical targets for therapeutic intervention including the repurposing of current drugs.
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http://dx.doi.org/10.3748/wjg.v25.i38.5732DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6801186PMC
October 2019

A novel cancer syndrome caused by -deficiency in the golden Syrian hamster.

J Carcinog 2018 10;17. Epub 2018 Oct 10.

Department of Biomedical Sciences, University of Minnesota Medical School, Duluth, MN, USA.

Background: The golden Syrian hamster is an emerging model organism. To optimize its use, our group has made the first genetically engineered hamsters. One of the first genes that we investigated is which encodes for the KCNQ1 potassium channel and also has been implicated as a tumor suppressor gene.

Materials And Methods: We generated knockout (KO) hamsters by CRISPR/Cas9-mediated gene targeting and investigated the effects of KCNQ1-deficiency on tumorigenesis.

Results: By 70 days of age seven of the eight homozygous KOs used in this study began showing signs of distress, and on necropsy six of the seven ill hamsters had visible cancers, including T-cell lymphomas, plasma cell tumors, hemangiosarcomas, and suspect myeloid leukemias.

Conclusions: None of the hamsters in our colony that were wild-type or heterozygous for mutations developed cancers indicating that the cancer phenotype is linked to -deficiency. This study is also the first evidence linking KCNQ1-deficiency to blood cancers.
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http://dx.doi.org/10.4103/jcar.JCar_5_18DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6187935PMC
October 2018

Loss of KCNQ1 expression in stage II and stage III colon cancer is a strong prognostic factor for disease recurrence.

Br J Cancer 2016 Dec 17;115(12):1565-1574. Epub 2016 Nov 17.

Department of Pathology, VU University Medical Center, Amsterdam 1081HV, The Netherlands.

Background: Colorectal cancer (CRC) is the third most common cancer worldwide. Accurately identifying stage II CRC patients at risk for recurrence is an unmet clinical need. KCNQ1 was previously identified as a tumour suppressor gene and loss of expression was associated with poor survival in patients with CRC liver metastases. In this study the prognostic value of KCNQ1 in stage II and stage III colon cancer patients was examined.

Methods: KCNQ1 mRNA expression was assessed in 90 stage II colon cancer patients (AMC-AJCCII-90) using microarray gene expression data. Subsequently, KCNQ1 protein expression was evaluated in an independent cohort of 386 stage II and stage III colon cancer patients by immunohistochemistry of tissue microarrays.

Results: Low KCNQ1 mRNA expression in stage II microsatellite stable (MSS) colon cancers was associated with poor disease-free survival (DFS) (P=0.025). Loss of KCNQ1 protein expression from epithelial cells was strongly associated with poor DFS in stage II MSS (P<0.0001), stage III MSS (P=0.0001) and stage III microsatellite instable colon cancers (P=0.041). KCNQ1 seemed an independent prognostic value in addition to other high-risk parameters like angio-invasion, nodal stage and microsatellite instability-status.

Conclusions: We conclude that KCNQ1 is a promising biomarker for prediction of disease recurrence and may aid stratification of patients with stage II MSS colon cancer for adjuvant chemotherapy.
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http://dx.doi.org/10.1038/bjc.2016.376DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5155368PMC
December 2016

Secreted Phospholipases A2 Are Intestinal Stem Cell Niche Factors with Distinct Roles in Homeostasis, Inflammation, and Cancer.

Cell Stem Cell 2016 07 9;19(1):38-51. Epub 2016 Jun 9.

Department of Pathology, Erasmus MC Cancer Institute, Rotterdam 3000CA, The Netherlands. Electronic address:

The intestinal stem cell niche provides cues that actively maintain gut homeostasis. Dysregulation of these cues may compromise intestinal regeneration upon tissue insult and/or promote tumor growth. Here, we identify secreted phospholipases A2 (sPLA2s) as stem cell niche factors with context-dependent functions in the digestive tract. We show that group IIA sPLA2, a known genetic modifier of mouse intestinal tumorigenesis, is expressed by Paneth cells in the small intestine, while group X sPLA2 is expressed by Paneth/goblet-like cells in the colon. During homeostasis, group IIA/X sPLA2s inhibit Wnt signaling through intracellular activation of Yap1. However, upon inflammation they are secreted into the intestinal lumen, where they promote prostaglandin synthesis and Wnt signaling. Genetic ablation of both sPLA2s improves recovery from inflammation but increases colon cancer susceptibility due to release of their homeostatic Wnt-inhibitory role. This "trade-off" effect suggests sPLA2s have important functions as genetic modifiers of inflammation and colon cancer.
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http://dx.doi.org/10.1016/j.stem.2016.05.023DOI Listing
July 2016

Circulating miRNAs as novel potential biomarkers for esophageal squamous cell carcinoma diagnosis: a meta-analysis update.

Dis Esophagus 2017 Feb;30(2):1-9

Department of Epidemiology and Health Statistics, School of Public Health, Capital Medical University, Beijing, China.

Early detection of esophageal squamous cell carcinoma (ESCC) is urgently needed to reduce the high morbidity and mortality of disease. Circulating microRNAs (miRNAs) are promising molecular biomarkers for ESCC prediction. We performed a comprehensive meta-analysis to systematically evaluate the diagnostic accuracy of circulating miRNAs in diagnosis of ESCC patients. Eligible studies were identified and assessed for quality employing multiple search strategies. Summary estimates for sensitivity, specificity, and other measures of accuracy of miRNAs in the diagnosis of ESCC were pooled using the bivariate random effects model. A total of 27 studies from 11 published articles were included in the meta-analysis. The overall sensitivity, specificity, positive likelihood ratio, negative likelihood ratio, and diagnostic odds ratio of circulating miRNAs for the diagnosis of ESCC were 79.9% (95% confidence intervals [CI]: 76.2%-83.1%), 81.3% (95% CI: 75.7-85.9), 4.27 (95%CI: 3.27-5.58), 0.25 (95% CI: 0.21-0.29), and 17.29 (95% CI: 12.01-24.86), respectively. The area under the summary receiver operating characteristic curve was 0.87 (95% CI: 0.84-0.90). The subgroup analyses based on research country (China vs. Japan), specimen type (plasma vs. serum), miRNAs profiling (single vs. multiple), and test method (screening vs. candidate; Taqman vs. SYBR) indicated no significant difference in the diagnostic accuracy of each subgroup. Collectively, our findings indicate that circulating miRNAs have significant potential to be used as noninvasive biomarkers for early detection of ESCC. Moreover, the subgroup analyses demonstrated the feasibility of using blood miRNAs as an ESCC diagnostic biomarker in Japanese and Chinese populations. Further, both plasma and serum are recommended as clinical specimens for miRNA detection. Further studies will be needed to validate these findings using larger numbers of patients.
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http://dx.doi.org/10.1111/dote.12489DOI Listing
February 2017

Overexpression of phospholipase A2 Group IIA in esophageal squamous cell carcinoma and association with cyclooxygenase-2 expression.

Asian Pac J Cancer Prev 2014 ;15(21):9417-21

Department of Epidemiology and Health Statistics, School of Public Health, Capital Medical University, Beijing, China E-mail :

Background: Esophageal cancer is one of the most frequently occurring malignancies and the seventh leading cause of cancer-related deaths in the world. The esophageal squamous cell carcinoma (ESCC) is the most common histological type of esophageal cancer worldwide.

Materials And Methods: Our goal in this study was to detect phospholipase A2 Group IIA (PLA2G2A) and cyclooxygenase-2 (COX-2) immuno-expression in ESCC in a high- risk population in China.

Results: Positive expression of PLA2G2A protein was observed in 57.2% (166/290) of the cases, while COX-2 was found in 257 of 290 samples (88.6%), both PLA2G2A and COX-2 being expressed in 153 cases (52.8%), with a significant agreement (Kappa=0.091, p=0.031).Overexpression of PLA2G2A was significantly correlated with the depth of invasion (p=0.001). Co-expression of PLA2G2A and COX-2 not only significantly correlated with the depth of invasion (p=0.004) but also with TNM stage (p=0.04).

Conclusions: Our results showed that in patients with ESCC, PLA2G2A overexpression and PLA2G2A co-expression with COX-2 is significantly correlated with advanced stage. The biological role and pathophysiologic regulation of PLA2G2A and COX-2 overexpression in ESCC deserve further investigation.
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http://dx.doi.org/10.7314/apjcp.2014.15.21.9417DOI Listing
July 2015

Association of single nucleotide polymorphisms in the prostaglandin-endoperoxide synthase 2 (PTGS2) and phospholipase A₂ group IIA (PLA2G2A) genes with susceptibility to esophageal squamous cell carcinoma.

Asian Pac J Cancer Prev 2014 ;15(4):1797-802

Department of Epidemiology and Health Statistics, School of Public Health, Capital Medical University, Beijing, China E-mail :

Background: The prostaglandin-endoperoxide synthase 2 (PTGS2) and phospholipase A2 group IIA (PLA2G2A) genes encode enzymes that are involved in arachidonic acid and prostaglandin biosynthesis. Dysregulation of both genes is associated with inflammation and carcinogenesis, including esophageal squamous cell carcinoma (ESCC). We therefore hypothesized that there is an association between single nucleotide polymorphisms (SNPs) in these genes and susceptibility to ESCC.

Methods: We performed a gene-wide tag SNP-based association study to examine the association of SNPs in PTGS2 and PLA2G2A with ESCC in 269 patients and 269 healthy controls from Taihangshan Mountain, Henan and Hebei Provinces, the rural area of China which has the highest incidence of esophageal cancer in the world. Thirteen tag SNPs in PLA2G2A and 4 functional SNPs in PTGS2 were selected and genotyped using a high-throughput Mass Array genotyping platform.

Results: We found a modest increased risk of ESCC in subjects with the PTGS2 rs12042763 AA genotype (OR=1.23; 95% CI, 1.00- 3.04) compared with genotype GG. For PLA2G2A, a decreased risk of ESCC was observed in subjects with the rs11677 CT (OR=0.51, 95%CI, 0.29-0.85) or TT genotype (OR=0.51, 95%CI, 0.17-0.96) or the T carriers (CT+TT) (OR=0.52, 95%CI, 0.31-0.85) when compared with the CC genotype. Also for PLA2G2A, rs2236771 C allele carriers were more frequent in the control group (P=0.02). Subjects with the GC (OR=0.55, 95%CI, 0.33-0.93) or CC genotype (OR=0.38, 95% CI, 0.16-0.94) or the C carriers (GC+CC) (OR=0.52, 95%CI, 0.32- 0.85) showed a negative association with ESCC susceptibility.

Conclusions: Our results suggest that PTGS2 and PLA2G2A gene polymorphisms may modify the risk of ESCC development.
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http://dx.doi.org/10.7314/apjcp.2014.15.4.1797DOI Listing
November 2014

A dominantly acting murine allele of Mcm4 causes chromosomal abnormalities and promotes tumorigenesis.

PLoS Genet 2012 1;8(11):e1003034. Epub 2012 Nov 1.

School of Pharmacy and UW Carbone Cancer Center, University of Wisconsin Madison, Madison, WI, USA.

Here we report the isolation of a murine model for heritable T cell lymphoblastic leukemia/lymphoma (T-ALL) called Spontaneous dominant leukemia (Sdl). Sdl heterozygous mice develop disease with a short latency and high penetrance, while mice homozygous for the mutation die early during embryonic development. Sdl mice exhibit an increase in the frequency of micronucleated reticulocytes, and T-ALLs from Sdl mice harbor small amplifications and deletions, including activating deletions at the Notch1 locus. Using exome sequencing it was determined that Sdl mice harbor a spontaneously acquired mutation in Mcm4 (Mcm4(D573H)). MCM4 is part of the heterohexameric complex of MCM2-7 that is important for licensing of DNA origins prior to S phase and also serves as the core of the replicative helicase that unwinds DNA at replication forks. Previous studies in murine models have discovered that genetic reductions of MCM complex levels promote tumor formation by causing genomic instability. However, Sdl mice possess normal levels of Mcms, and there is no evidence for loss-of-heterozygosity at the Mcm4 locus in Sdl leukemias. Studies in Saccharomyces cerevisiae indicate that the Sdl mutation produces a biologically inactive helicase. Together, these data support a model in which chromosomal abnormalities in Sdl mice result from the ability of MCM4(D573H) to incorporate into MCM complexes and render them inactive. Our studies indicate that dominantly acting alleles of MCMs can be compatible with viability but have dramatic oncogenic consequences by causing chromosomal abnormalities.
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http://dx.doi.org/10.1371/journal.pgen.1003034DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3486839PMC
May 2013

New methods for finding common insertion sites and co-occurring common insertion sites in transposon- and virus-based genetic screens.

Nucleic Acids Res 2012 May 12;40(9):3822-33. Epub 2012 Jan 12.

Division of Biostatistics, School of Public Health, University of Minnesota, Minneapolis, MN 55455, USA.

Insertional mutagenesis screens in mice are used to identify individual genes that drive tumor formation. In these screens, candidate cancer genes are identified if their genomic location is proximal to a common insertion site (CIS) defined by high rates of transposon or retroviral insertions in a given genomic window. In this article, we describe a new method for defining CISs based on a Poisson distribution, the Poisson Regression Insertion Model, and show that this new method is an improvement over previously described methods. We also describe a modification of the method that can identify pairs and higher orders of co-occurring common insertion sites. We apply these methods to two data sets, one generated in a transposon-based screen for gastrointestinal tract cancer genes and another based on the set of retroviral insertions in the Retroviral Tagged Cancer Gene Database. We show that the new methods identify more relevant candidate genes and candidate gene pairs than found using previous methods. Identification of the biologically relevant set of mutations that occur in a single cell and cause tumor progression will aid in the rational design of single and combinatorial therapies in the upcoming age of personalized cancer therapy.
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http://dx.doi.org/10.1093/nar/gkr1295DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3351147PMC
May 2012

Runx1 is a tumor suppressor gene in the mouse gastrointestinal tract.

Cancer Sci 2012 Mar 19;103(3):593-9. Epub 2012 Jan 19.

Department of Pathology, VU University Medical Center, Amsterdam, Netherlands.

The Runx1 transcription factor plays an important role in tissue homeostasis through its effects on stem/progenitor cell populations and differentiation. The effect of Runx1 on epithelial differentiation of the secretory cell lineage of the colon was recently demonstrated. This study aimed to examine the role of Runx1 in tumor development in epithelial cells of the gastrointestinal tract. Conditional knockout mice that lacked Runx1 expression in epithelial cells of the GI tract were generated. These mice were crossed onto the Apc(Min) background, killed and their intestinal tumor phenotypes were compared with Apc(Min) Runx1 wild-type control mice. Apc-wild-type Runx1-mutant mice were also examined for tumor development. Colons from Runx1 knockout and wild-type mice were used for genome-wide mRNA expression analyses followed by gene-specific quantitative RT-PCR of whole colon and colon epithelium to identify Runx1 target genes. Runx1 deficiency in intestinal epithelial cells significantly enhanced tumorigenesis in Apc(Min) mice. Notably, epithelial Runx1 deficiency in Apc-wild-type mice was sufficient to cause tumor development. Absence of Runx1 was associated with global changes in the expression of genes involved in inflammation and intestinal metabolism, and with gene sets indicative of a metastatic phenotype and poor prognosis. Gene-specific analysis of Runx1-deficient colon epithelium revealed increased expression of genes linked to an expansion of the stem/progenitor cell population. These results identify Runx1 as a novel tumor suppressor gene for gastrointestinal tumors and support a role for Runx1 in maintaining the balance between the intestinal stem/progenitor cell population and epithelial differentiation of the GI tract.
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http://dx.doi.org/10.1111/j.1349-7006.2011.02189.xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5439111PMC
March 2012

A Sleeping Beauty transposon-mediated screen identifies murine susceptibility genes for adenomatous polyposis coli (Apc)-dependent intestinal tumorigenesis.

Proc Natl Acad Sci U S A 2011 Apr 21;108(14):5765-70. Epub 2011 Mar 21.

Department of Genetics, Cell Biology and Development, Center for Genome Engineering, Masonic Cancer Center, University of Minnesota, Minneapolis, MN 55455, USA.

It is proposed that a progressive series of mutations and epigenetic events leads to human colorectal cancer (CRC) and metastasis. Furthermore, data from resequencing of the coding regions of human CRC suggests that a relatively large number of mutations occur in individual human CRC, most at low frequency. The functional role of these low-frequency mutations in CRC, and specifically how they may cooperate with high-frequency mutations, is not well understood. One of the most common rate-limiting mutations in human CRC occurs in the adenomatous polyposis coli (APC) gene. To identify mutations that cooperate with mutant APC, we performed a forward genetic screen in mice carrying a mutant allele of Apc (Apc(Min)) using Sleeping Beauty (SB) transposon-mediated mutagenesis. Apc(Min) SB-mutagenized mice developed three times as many polyps as mice with the Apc(Min) allele alone. Analysis of transposon common insertion sites (CIS) identified the Apc locus as a major target of SB-induced mutagenesis, suggesting that SB insertions provide an efficient route to biallelic Apc inactivation. We also identified an additional 32 CIS genes/loci that may represent modifiers of the Apc(Min) phenotype. Five CIS genes tested for their role in proliferation caused a significant change in cell viability when message levels were reduced in human CRC cells. These findings demonstrate the utility of using transposon mutagenesis to identify low-frequency and cooperating cancer genes; this approach will aid in the development of combinatorial therapies targeting this deadly disease.
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http://dx.doi.org/10.1073/pnas.1018012108DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3078351PMC
April 2011

Pla2g2a attenuates colon tumorigenesis in azoxymethane-treated C57BL/6 mice; expression studies reveal Pla2g2a target genes and pathways.

Cell Oncol 2009 ;31(5):345-56

Department of Pathology, VU University Medical Center, Amsterdam, The Netherlands.

Background: The group IIA secretory phospholipase A2 gene, Pla2g2a, confers resistance to intestinal tumorigenesis in the Apc(Min/+) mouse model. However, it is unclear how Pla2g2a exerts its tumor-suppressive effects and whether its mode of action depends on Apc-germline mutations.

Methods: We tested whether expression of a Pla2g2a transgene provides protection against carcinogen-induced colon tumors, and examined whether the normal colon microenvironment is modulated by Pla2g2a expression.

Results: Pla2g2a strongly inhibited colon tumorigenesis in mice following treatment with the DNA alkylating agent azoxymethane (AOM). Moreover, AOM-induced duodenal tumors were also attenuated by Pla2g2a expression. These tumors demonstrated upregulation of beta-catenin, indicative of involvement of the Wnt signaling pathway. Comparison of genome-wide microarray expression profiles of healthy (non-pathologic) colon tissues from Pla2g2a-transgenic to non-transgenic mice revealed 382 genes that were differentially expressed, comprising clusters of genes involved in inflammation and microbial defense, cell signaling and cell cycle, transactivation, apoptosis and mitochondrial function, DNA repair, and lipid and energy metabolism. Pathway analysis using Gene Set Enrichment Analysis (GSEA) indicated that Pla2g2a suppresses the expression of interferon-induced genes.

Conclusion: Our results demonstrate that Pla2g2a attenuates colon tumorigenesis independent of Apc-germline mutations, and reveal Pla2g2a target genes and pathways in non-pathologic colon microenvironment that influence conditions for colorectal cancer development.
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http://dx.doi.org/10.3233/CLO-2009-0480DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4619055PMC
December 2009

A transposon-based genetic screen in mice identifies genes altered in colorectal cancer.

Science 2009 Mar 26;323(5922):1747-50. Epub 2009 Feb 26.

Department of Genetics, Cell Biology and Development, Center for Genome Engineering, Masonic Cancer Center, University of Minnesota, Minneapolis, MN 55455, USA.

Human colorectal cancers (CRCs) display a large number of genetic and epigenetic alterations, some of which are causally involved in tumorigenesis (drivers) and others that have little functional impact (passengers). To help distinguish between these two classes of alterations, we used a transposon-based genetic screen in mice to identify candidate genes for CRC. Mice harboring mutagenic Sleeping Beauty (SB) transposons were crossed with mice expressing SB transposase in gastrointestinal tract epithelium. Most of the offspring developed intestinal lesions, including intraepithelial neoplasia, adenomas, and adenocarcinomas. Analysis of over 16,000 transposon insertions identified 77 candidate CRC genes, 60 of which are mutated and/or dysregulated in human CRC and thus are most likely to drive tumorigenesis. These genes include APC, PTEN, and SMAD4. The screen also identified 17 candidate genes that had not previously been implicated in CRC, including POLI, PTPRK, and RSPO2.
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http://dx.doi.org/10.1126/science.1163040DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2743559PMC
March 2009

Loss of EphA2 receptor tyrosine kinase reduces ApcMin/+ tumorigenesis.

Int J Cancer 2009 Mar;124(6):1366-71

University of Minnesota Medical School, Duluth, MN 55812, USA.

The Eph receptor A2 (EphA2) is overexpressed in a range of human epithelial cancers, a phenotype that is associated with cancer cell proliferation, progression and angiogenesis. Mouse models of mammary neoplasia have confirmed the role of EphA2 as mice carrying a knockout allele of EphA2 were resistant to breast cancer, a phenotype that was associated with interactions between EphA2 and ErbB2. We investigated in vivo the role of EphA2 in GI cancer. To determine whether EphA2 influences intestinal tumorigenesis, we used qRT-PCR to examine the mRNA expression levels of EphA2 in tumors from the small intestine and colon of Apc(Min/+) mice. We found that EphA2 was significantly up-regulated in tumors from both regions when compared with normal control tissues. We then evaluated the spatial expression patterns of EphA2 protein using immunohistochemistry in both the small intestine and colon and found that in normal tissues EphA2 was robustly expressed in highly differentiated cells, such as cells of the villi, but that EphA2 expression was largely absent from the stem cell niche and proliferative zones of intestinal crypts. In contrast, in tumors EphA2 was broadly expressed. Finally, we created a strain of Apc(Min/+) mice carrying a genetic knockout of the EphA2 gene. These mice developed significantly fewer and smaller tumors in both the small and large intestine. Overall, our results indicate that EphA2 plays an oncogenic role in the mammalian intestine suggesting that strategies to target EphA2 activity may offer new therapeutic modalities for colorectal cancer.
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http://dx.doi.org/10.1002/ijc.24083DOI Listing
March 2009

Interaction of Muc2 and Apc on Wnt signaling and in intestinal tumorigenesis: potential role of chronic inflammation.

Cancer Res 2008 Sep;68(18):7313-22

Strang Cancer Center at New York Blood Bank, New York, USA.

Somatic mutations of the adenomatous polyposis coli (APC) gene are initiating events in the majority of sporadic colon cancers. A common characteristic of such tumors is reduction in the number of goblet cells that produce the mucin MUC2, the principal component of intestinal mucus. Consistent with these observations, we showed that Muc2 deficiency results in the spontaneous development of tumors along the entire gastrointestinal tract, independently of deregulated Wnt signaling. To dissect the complex interaction between Muc2 and Apc in intestinal tumorigenesis and to elucidate the mechanisms of tumor formation in Muc2(-/-) mice, we crossed the Muc2(-/-) mouse with two mouse models, Apc(1638N/+) and Apc(Min/+), each of which carries an inactivated Apc allele. The introduction of mutant Muc2 into Apc(1638N/+) and Apc(Min/+) mice greatly increased transformation induced by the Apc mutation and significantly shifted tumor development toward the colon as a function of Muc2 gene dosage. Furthermore, we showed that in compound double mutant mice, deregulation of Wnt signaling was the dominant mechanism of tumor formation. The increased tumor burden in the distal colon of Muc2/Apc double mutant mice was similar to the phenotype observed in Apc(Min/+) mice that are challenged to mount an inflammatory response, and consistent with this, gene expression profiles of epithelial cells from flat mucosa of Muc2-deficient mice suggested that Muc2 deficiency was associated with low levels of subclinical chronic inflammation. We hypothesize that Muc2(-/-) tumors develop through an inflammation-related pathway that is distinct from and can complement mechanisms of tumorigenesis in Apc(+/-) mice.
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http://dx.doi.org/10.1158/0008-5472.CAN-08-0598DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2698434PMC
September 2008

The roles of sPLA2-IIA (Pla2g2a) in cancer of the small and large intestine.

Front Biosci 2008 May 1;13:4144-74. Epub 2008 May 1.

Department of Medical Oncology, VU University Medical Center, Amsterdam, The Netherlands.

The mouse secretory phospholipase A2 group IIA (sPLA2-IIA) gene Pla2g2a has been identified as a susceptibility gene for cancer of the small and large intestine. Interestingly, unlike most previously identified tumor susceptibility genes, Pla2g2a does not behave like a classical oncogene or tumor suppressor gene. Hence, identification of its biological functions in tumor development may shed new light on general mechanisms that modulate colon cancer risk. So far, sPLA2-IIA has been proposed to play a role in anti-bacterial defense, inflammation and eicosanoid generation, in clearance of apoptotic cells, and in the Wnt signaling pathway. More recently, comparison of RNA expression profiles of colon from Pla2g2a-transgenic to Pla2g2a-deficient mice confirmed and even extended sPLA2-IIA's diverse biological effects. In this review we aim to summarize current knowledge about the various links of sPLA2-IIA to cancer of the gastro-intestinal tract, and propose several models to illustrate its putative biological effects on tumor development.
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http://dx.doi.org/10.2741/2998DOI Listing
May 2008

Intestinal-specific PPARgamma deficiency enhances tumorigenesis in ApcMin/+ mice.

Int J Cancer 2006 Nov;119(10):2339-46

Department of Biochemistry and Molecular Biology, University of Minnesota Medical School, Duluth, USA.

Multiple investigations of the effects of peroxisome proliferator-activated receptor gamma (PPARgamma) ligands on colon cancer have produced contradictory results. While some studies demonstrated increased numbers of colonic polyps in Apc(Min/+) mice treated with various thiazolidinedione (TZD) PPARgamma ligands, others reported amelioration of tumor multiplicity and progression in both Apc(Min/+) mice and in mice with chemically-induced colon cancer. Here, we addressed the role of PPARgamma in murine intestinal tumorigenesis using gene knockout methodology. We found that either heterozygous or homozygous intestinal-specific PPARgamma deficiency enhanced the number of Apc(Min/+) tumors in both the small intestine and colon, especially in the colon, where PPARgamma deficiency also modulated tumor incidence. Gender significantly affected tumor multiplicity independent of PPARgamma genotype. Female Apc(Min/+) mice developed more tumors in the small intestine and more tumors overall, whereas male Apc(Min/+) mice developed more tumors in the colon. Nevertheless, intestinal PPARgamma deficiency enhanced tumorigenesis irrespective of gender. Our results suggest that PPARgamma functions as a tumor resistance factor in the mouse intestine and warrant further investigation of the PPARgamma-dependent and independent actions of TZDs in cancer.
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http://dx.doi.org/10.1002/ijc.22115DOI Listing
November 2006