transforming-growth-factor-beta and Intestinal-Neoplasms

In the human body, mucosal surfaces of the intestinal tract are the largest and one of the most complex parts of the immune system. These surfaces are covered by a layer of epithelial cells which allows efficient absorption of nutrients but also serves to separate the intestine from an environment loaded with potential harmful agents. Discrimination between beneficial commensal bacteria, harmless antigens and pathogenic microorganisms is a central issue in the role that gut immune cells play in maintaining the balance between immune response and tolerance. However, the basis of this discrimination in the mucosal immune system, where this occurs and how it can affect both local and systemic responses is not yet well understood. Nevertheless, antigen uptake and presentation seems to be a crucial factor in this issue. In this review, we will discuss the key role of immune intestinal cells in the development of mucosal immunity, tolerance and disease.

Topics: Animals; Bacteria; Colitis; Dendritic Cells; Epithelial Cells; Humans; Immune Tolerance; Immunity, Mucosal; Interleukin-10; Intestinal Mucosa; Intestinal Neoplasms; Intestines; Lymph Nodes; Macrophages; Peyer's Patches; T-Lymphocytes, Regulatory; Transforming Growth Factor beta; Tumor Escape

Mutations in the APC gene and other genes in the Wnt signaling pathway contribute to development of colorectal carcinomas. R-spondins (RSPOs) are secreted proteins that amplify Wnt signaling in intestinal stem cells. Alterations in RSPO genes have been identified in human colorectal tumors. We studied the effects of RSPO1 overexpression in Apc. An adeno associated viral vector encoding RSPO1-Fc fusion protein, or control vector, was injected into Apc. Intestines from Apc. Expression of RSPO1 in Apc

Topics: Adenoma; Animals; Disease Models, Animal; Intestinal Neoplasms; Mice; Organoids; Thrombospondins; Transforming Growth Factor beta; Wnt Signaling Pathway

Topics: Basic Helix-Loop-Helix Transcription Factors; Carcinogenesis; Cell Line, Tumor; Cell Movement; Cell Proliferation; Cell Survival; Down-Regulation; Epithelial-Mesenchymal Transition; Gene Expression Regulation, Neoplastic; Humans; Intestinal Neoplasms; Neoplasm Invasiveness; Neuroendocrine Tumors; Oncostatin M; Pancreatic Neoplasms; RNA, Long Noncoding; Signal Transduction; Stomach Neoplasms; Transcription, Genetic; Transforming Growth Factor beta

As an inhibitor of apoptosis (IAP) family member, Survivin is known for its role during regulation of apoptosis. More recently its function as a cell cycle regulator has become evident. Survivin was shown to play a pivotal role during embryonic development and is highly expressed in regenerative tissue as well as in many cancer types. We examined the function of Survivin during mouse intestinal organogenesis and in gut pathophysiology. We found high expression of Survivin in experimentally induced colon cancer in mice but also in colon tumors of humans. Moreover, Survivin was regulated by TGF-β and was found to be highly expressed during mucosal healing following intestinal inflammation. We identified that expression of Survivin is essential early on in life, as specific deletion of Survivin in Villin expressing cells led to embryonic death around day 12 post coitum. Together with our recent study on the role of Survivin in the gut of adult mice our data demonstrate that Survivin is an essential guardian of embryonic gut development and adult gut homeostasis protecting the epithelium from cell death promoting the proliferation of intestinal stem and progenitor cells.

Topics: Animals; Embryonic Development; Enterocytes; Female; Gene Deletion; Homeostasis; Humans; Inflammation; Inhibitor of Apoptosis Proteins; Intestinal Neoplasms; Intestines; Male; Mice; Mitosis; Repressor Proteins; Stem Cell Niche; Survivin; Transforming Growth Factor beta

Genetic alterations in the TGFβ signaling pathway in combination with oncogenic alterations lead to cancer development in the intestines. However, the mechanisms of TGFβ signaling suppression in malignant progression of intestinal tumors have not yet been fully understood. We have examined Apc(Δ716) Tgfbr2(ΔIEC) compound mutant mice that carry mutations in Apc and Tgfbr2 genes in the intestinal epithelial cells. We found inflammatory microenvironment only in the invasive intestinal adenocarcinomas but not in noninvasive benign polyps of the same mice. We thus treated simple Tgfbr2(ΔIEC) mice with dextran sodium sulfate (DSS) that causes ulcerative colitis. Importantly, these Tgfbr2(ΔIEC) mice developed invasive colon cancer associated with chronic inflammation. We also found that TGFβ signaling is suppressed in human colitis-associated colon cancer cells. In the mouse invasive tumors, macrophages infiltrated and expressed MT1-MMP, causing MMP2 activation. These results suggest that inflammatory microenvironment contributes to submucosal invasion of TGFβ signaling-repressed epithelial cells through activation of MMP2. We further found that regeneration was impaired in Tgfbr2(ΔIEC) mice for intestinal mucosa damaged by DSS treatment or X-ray irradiation, resulting in the expansion of undifferentiated epithelial cell population. Moreover, organoids of intestinal epithelial cells cultured from irradiated Tgfbr2(ΔIEC) mice formed "long crypts" in Matrigel, suggesting acquisition of an invasive phenotype into the extracellular matrix. These results, taken together, indicate that a simple genetic alteration in the TGFβ signaling pathway in the inflamed and regenerating intestinal mucosa can cause invasive intestinal tumors. Such a mechanism may play a role in the colon carcinogenesis associated with inflammatory bowel disease in humans.

Topics: Adenomatous Polyposis Coli Protein; Animals; Cell Proliferation; Colonic Neoplasms; Female; Gene Expression Regulation, Neoplastic; Humans; Intestinal Mucosa; Intestinal Neoplasms; Matrix Metalloproteinase 2; Mice; Mice, Transgenic; Protein Serine-Threonine Kinases; Receptor, Transforming Growth Factor-beta Type II; Receptors, Transforming Growth Factor beta; Signal Transduction; Transforming Growth Factor beta; Tumor Microenvironment

In the majority of microsatellite-stable colorectal cancers (CRCs), an initiating mutation occurs in the adenomatous polyposis coli (APC) or β-catenin gene, activating the β-catenin/TCF pathway. The progression of resulting adenomas is associated with oncogenic activation of KRas and inactivation of the p53 and TGF-β/Smad functions. Most established CRC cell lines contain mutations in the TGF-β/Smad pathway, but little is known about the function of TGF-β in the early phases of intestinal tumorigenesis. We used mouse and human ex vivo 3D intestinal organoid cultures and in vivo mouse models to study the effect of TGF-β on the Lgr5(+) intestinal stem cells and their progeny in intestinal adenomas. We found that the TGF-β-induced apoptosis in Apc-mutant organoids, including the Lgr5(+) stem cells, was mediated by up-regulation of the BH3-only proapoptotic protein Bcl-2-like protein 11 (Bim). BH3-mimetic compounds recapitulated the effect of Bim not only in the adenomas but also in human CRC organoids that had lost responsiveness to TGF-β-induced apoptosis. However, wild-type intestinal crypts were markedly less sensitive to TGF-β than Apc-mutant adenomas, whereas the KRas oncogene increased resistance to TGF-β via the activation of the Erk1/2 kinase pathway, leading to Bim down-regulation. Our studies identify Bim as a critical mediator of TGF-β-induced apoptosis in intestinal adenomas and show that the common progression mutations modify Bim levels and sensitivity to TGF-β during intestinal adenoma development.

Topics: Adenoma; Animals; Apoptosis; Apoptosis Regulatory Proteins; Bcl-2-Like Protein 11; Blotting, Western; Cells, Cultured; Chromatography, Gel; DNA Primers; Flow Cytometry; Gene Expression Regulation, Neoplastic; Humans; Intestinal Neoplasms; Membrane Proteins; Mice; Microarray Analysis; Organoids; Proto-Oncogene Proteins; Receptors, G-Protein-Coupled; Reverse Transcriptase Polymerase Chain Reaction; Stem Cells; Transforming Growth Factor beta

Epidemiological and experimental evidence suggests that estrogen replacement therapy reduces the risk of colon cancer in postmenopausal women. Estrogen receptor beta (ERβ) is thought to be the principal mediator of the estrogen effect in the colon. Recent studies by our team suggested positive regulation of the transforming growth factor (TGF)β pathway by estrogen in mice colonocytes. We therefore wanted to investigate the effects of ERβ agonist treatment on intestinal tumorigenesis in Apc(Min/+) mice. Weaned Apc(Min/+) mice were injected subcutaneously three times a week for 12 wk with vehicle or ERβ-selective agonist, diarylpropionitrile (DPN, 5 mg/kg). DPN administration resulted in a significant reduction in small intestinal polyp multiplicity in both Apc(Min/+) male and female mice. Furthermore, the mean diameter of small intestinal polyps was lower in DPN-treated than vehicle-treated males, along with lower BrdU incorporation indices in jejunal and colon epithelial cells of both sexes. DPN treatment also increased apoptosis in colon epithelium as measured by TUNEL assay and cleaved caspase 3 quantification. The effect of DPN on various components of the TGFβ pathway was also studied in colonocytes. DPN treatment increased expression of TGFβ1 and TGFβ3 transcripts, levels of nuclear and phosphorylated Smad2 as well as p27 cell-cycle inhibitor, a TGFβ pathway target gene. Our results demonstrate that DPN treatment reduces intestinal tumorigenesis in Apc(Min/+) mice. Furthermore, we suggest that positive regulation of the TGFβ pathway by ERβ activation could contribute to the protective role of estrogen in intestinal tumor development.

Topics: Adenomatous Polyposis Coli Protein; Animals; Apoptosis; Blotting, Western; Caspase 3; Cell Nucleus; Cell Proliferation; Colon; Epithelium; Estrogen Receptor beta; Female; Gene Expression; In Situ Nick-End Labeling; Injections, Subcutaneous; Intestinal Neoplasms; Intestinal Polyps; Male; Mice; Mice, Inbred C57BL; Mice, Mutant Strains; Nitriles; Phosphorylation; Propionates; Reverse Transcriptase Polymerase Chain Reaction; Smad2 Protein; Transforming Growth Factor beta

Anti-inflammatory drugs prevent intestinal tumor formation, an activity related to their ability to inhibit inflammatory pathway signaling in the target tissue. We previously showed that treatment of Min/(+) mice with the selective cyclooxygenase-2 (COX-2) inhibitor celecoxib induced rapid tumor regression; however, drug-resistant tumors appeared with long-term treatment. In this study, we investigated whole-tissue changes in inflammatory signaling by studying constituents of the tissue stroma and extracellular matrix. We found that celecoxib resistance was associated with changes in factors regulating autocrine transforming growth factor-beta (TGFbeta) signaling. Chronic drug treatment expanded the population of bone marrow-derived CD34(+) vimentin(+) alphaSMA(-) myofibroblast precursors and alphaSMA(+) vimentin(+) F4/80(-) myofibroblasts in the lamina propria and submucosa, providing a source of increased TGFbeta and COX-2 expression. Membrane constituents regulating TGFbeta availability, including syndecan-1 and heparanase-1, were also modified by chronic treatment in a manner promoting increased TGFbeta signaling. Finally, long-term celecoxib treatment induced tissue fibrosis, as indicated by increased expression of collagen, fibronectin, and laminin in the basement membrane. We conclude that chronic COX-2 inhibition alters TGFbeta signaling in the intestinal mucosa, producing conditions consistent with chronic inflammation.

Topics: Animals; Celecoxib; Cyclooxygenase 2; Cyclooxygenase 2 Inhibitors; Extracellular Matrix; Female; Fibroblasts; Fibrosis; Genes, APC; Immunoblotting; Immunoenzyme Techniques; Intestinal Neoplasms; Intestines; Mice; Mice, Inbred C57BL; Polysaccharide-Lyases; Pyrazoles; Signal Transduction; Stromal Cells; Sulfonamides; Syndecan-1; Transforming Growth Factor beta

We have generated effector T cells from tumor-draining lymph nodes (TDLN) that are efficacious in adoptive immunotherapy. We now examine the effect of concomitant tumors on the generation of effector T cells. We inoculated methylcholanthrene (MCA) 205 in the flanks of normal mice and mice bearing MCA 205 lung metastases. TDLN cells from these mice were activated and expanded in vitro, and adoptively transferred to mice bearing lung metastases. Effector T cells generated from TDLN in mice with only flank tumor mediated potent antitumor activity. However, antitumor efficacy of the effector T cells generated from TDLN in mice with pre-existent lung tumor (cTDLN) was reduced. Phenotyping studies showed that dendritic cells in cTDLN expressed higher levels of B7-H1, whereas cTDLN T cells expressed higher levels of PD-1. The levels of IFNgamma were reduced, and the levels of CD4(+)Foxp3(+) regulatory T cells were increased in cTDLN versus TDLN. The in vitro activation of cTDLN was increased by blocking B7-H1 or transforming growth factor (TGF)-beta. Importantly, we found a synergistic up-regulation of IFNgamma with simultaneous blockade of B7-H1 and TGF-beta that was much greater than observed with TDLN. In vitro activation of cTDLN with anti-B7-H1 and anti-TGF-beta and in vivo administration of these antibodies after adoptive transfer resulted in the abrogation of the suppression associated with cTDLN. These results show a major role for the B7-H1/PD-1 axis and TGF-beta as synergistic suppressive mechanisms in cTDLN. Our data have clinical relevance in the generation of effector T cells in the tumor-bearing host.

Topics: Animals; Antigens, Surface; Apoptosis Regulatory Proteins; B7-1 Antigen; B7-H1 Antigen; Immune Tolerance; Intestinal Neoplasms; Lung Neoplasms; Lymphatic Metastasis; Lymphocyte Activation; Membrane Glycoproteins; Mice; Mice, Inbred C57BL; Models, Biological; Neoplasm Transplantation; Neoplasms, Second Primary; Peptides; Programmed Cell Death 1 Receptor; Sarcoma; Signal Transduction; Skin Neoplasms; T-Lymphocytes; Transforming Growth Factor beta; Tumor Cells, Cultured; Tumor Escape

The epithelial-mesenchymal transition (EMT) occurs commonly during carcinoma invasion and metastasis, but not during early tumorigenesis. Microarray data demonstrated elevation of vimentin, a mesenchymal marker, in intestinal adenomas from Apc Min/+ (Min) mice. We have tested the involvement of EMT in early tumorigenesis in mammalian intestines by following EMT-associated markers. Elevated vimentin RNA expression and protein production were detected within neoplastic cells in murine intestinal adenomas. Similarly, vimentin protein was detected in both adenomas and invasive adenocarcinomas of the human colon, but not in the normal colonic epithelium or in hyperplastic polyps. Expression of E-cadherin varied inversely with vimentin. In addition, the expression of fibronectin was elevated while that of E-cadherin decreased. Canonical E-cadherin suppressors, such as Snail, were not elevated in the same tumor. Elevated vimentin expression in the adenoma was not correlated with persistent Ras signaling, but was strongly correlated with reduced proliferation indices, active Wnt signaling, and TGF-beta signaling, as demonstrated by its dependence on Smad3. We designate our observations of expression of only some of the canonical features of EMT as "truncated EMT". These unexpected observations are interpreted as reflecting the involvement of a core of the EMT system during the tissue remodeling of early tumorigenesis.

Topics: Adenoma; Adenomatous Polyposis Coli Protein; Animals; Azoxymethane; Cadherins; Cell Proliferation; Epithelium; Fibronectins; Gene Expression Regulation, Neoplastic; Humans; Immunohistochemistry; Intestinal Neoplasms; Intestinal Polyps; Mesoderm; Mice; Mutation; Neoplasm Invasiveness; Phenotype; ras Proteins; Signal Transduction; Snail Family Transcription Factors; Transcription Factors; Transforming Growth Factor beta; Vimentin; Wnt Proteins

Clinical evidence suggests that estradiol replacement therapy reduces colon cancer risk in 'post'menopausal women. In colon epithelial cells, the estrogen receptor beta (ERbeta) is the predominant ER subtype and is thought to mediate the genomic effect of estrogens. The first aim of this study was to investigate the consequence of ERbeta deficiency on intestinal tumorigenesis in the Apc(Min/+) mouse model. Furthermore, to explore the biological mechanisms by which estrogens may influence the pathogenesis of colorectal cancer, we performed gene expression profiles in colonocytes from ovariectomized wild-type (WT) vs. ERbeta(-/-) mice, treated with estradiol (E(2)) or vehicle. Specifically in female, ERbeta deficiency was found to be associated with higher adenoma multiplicity in the small intestine, but not in the colon. Furthermore, tumors from ERbeta(-/-)Apc(Min/+) female mice were on average significantly larger than those from control Apc(Min/+) mice. Higher steady-state proliferation in epithelial cells of the jejunum and colon from ERbeta(-/-)Apc(Min/+) vs. Apc(Min/+) female mice was confirmed by BrdU incorporation assay. Interestingly, functional categorization of microarray results revealed the TGFbeta signaling pathway to be modulated in colonocytes, especially for the WT + E(2) vs. WT + Vehicle and the ERbeta(-/-) + E(2) vs. WT + E(2) comparisons. Using quantitative PCR analysis, we observed transcripts from ligands of the TGFbeta pathway to be upregulated in colonocytes from E(2)-treated WT and ERbeta(-/-) mice and downregulated in ERbeta-deficient mice, mostly in an E(2)-independent manner. Therefore, our results demonstrate that ERbeta deficiency enhances small intestinal tumorigenesis and suggest that modulation of the TGFbeta signaling pathway could contribute to the protective role of estrogens on intestinal tumorigenesis.

Topics: Adenoma; Animals; Bromodeoxyuridine; Colonic Neoplasms; Disease Models, Animal; Estrogen Receptor beta; Female; Gene Expression Profiling; Gene Expression Regulation, Neoplastic; Intestinal Neoplasms; Intestine, Small; Male; Mice; Mice, Inbred C57BL; Mice, Knockout; Mice, Mutant Strains; Oligonucleotide Array Sequence Analysis; Ovariectomy; Reverse Transcriptase Polymerase Chain Reaction; Signal Transduction; Transforming Growth Factor beta

Transforming growth factor-beta (TGF-beta) and Wnt ligands function in numerous developmental processes, and alterations of both signaling pathways are associated with common pathologic conditions, including cancer. To obtain insight into the extent of interdependence of the two signaling cascades in regulating biological responses, we used an oligonucleotide microarray approach to identify Wnt and TGF-beta target genes using normal murine mammary gland epithelial cells as a model. Combination treatment of TGF-beta and Wnt revealed a novel transcriptional program that could not have been predicted from single ligand treatments and included a cohort of genes that were cooperatively induced by both pathways. These included both novel and known components or modulators of TGF-beta and Wnt pathways, suggesting that mutual feedback is a feature of the coordinated activities of the ligands. The majority of the cooperative targets display increased expression in tumors derived from either Min (many intestinal neoplasia) or mouse mammary tumor virus (MMTV)-Wnt1 mice, two models of Wnt-induced tumors, with nine of these genes (Ankrd1, Ccnd1, Ctgf, Gpc1, Hs6st2, IL11, Inhba, Mmp14, and Robo1) showing increases in both. Reduction of TGF-beta signaling by expression of a dominant-negative TGF-beta type II receptor in bigenic MMTV-Wnt1/DNIIR mice increased mammary tumor latency and was correlated with a decrease in expression of Gpc1, Inhba, and Robo1, three of the TGF-beta/Wnt cooperative targets. Our results indicate that the TGF-beta and Wnt/beta-catenin pathways are firmly intertwined and generate a unique gene expression pattern that can contribute to tumor progression.

Topics: Adenoma; Animals; Cell Transformation, Neoplastic; Female; Gene Expression Regulation, Neoplastic; Humans; Intestinal Neoplasms; L Cells; Mammary Neoplasms, Experimental; Mice; Mice, Inbred C57BL; Mice, Transgenic; Signal Transduction; Transcription, Genetic; Transforming Growth Factor beta; Wnt Proteins; Wnt3 Protein

The Smad4(+/E6sad) mouse carries a null mutation in the endogenous Smad4 gene resulting in serrated adenomas and mixed polyposis of the upper gastrointestinal (GI) tract with 100% penetrance. Here, we show by loss of heterozygosity (LOH) analysis and immunohistochemistry (IHC) that, although the majority of the tumors appear at 9 months of age, somatic loss of the wild-type Smad4 allele occurs only at later stages of tumor progression. Hence, haploinsufficiency underlies Smad4-driven tumor initiation in the GI tract. As both the Apc and Smad4 tumor suppressor genes map to mouse chromosome 18, we have bred Smad4(+/E6sad) with the Apc(+/1638N) model to generate two distinct compound heterozygous lines carrying both mutations either in cis (CAS) or in trans (TAS). Strikingly, both models show increased tumor multiplicities when compared with the single mutant littermates, although CAS mice are more severely affected and became moribund at only 5-6 weeks of age. Phenotypic and molecular analyses indicate that Smad4 haploinsufficiency is sufficient to significantly affect tumor initiation and progression both prior to and upon loss of Apc function. Moreover, complete loss of Smad4 strongly enhances Apc-driven tumor formation.

Topics: Age of Onset; Animals; Disease Progression; DNA Mutational Analysis; Genes, APC; Immunohistochemistry; Intestinal Neoplasms; Loss of Heterozygosity; Mice; Mice, Inbred C57BL; Phenotype; Signal Transduction; Smad4 Protein; Transforming Growth Factor beta; Wnt Proteins

The small intestinal mucosa makes up about 90% of the total surface of the gastrointestinal tract. However, adenocarcinomas arise rarely in this location. To elucidate genetic alterations underlying tumour development in the small intestine we investigated 17 sporadic adenocarcinomas. By comparative genomic hybridization recurrent gains of chromosomal material were found at chromosomes 7, 8, 13q, and 20 (5/17, each), while non-random losses were seen at 8p, 17p (4/17, each), and 18 (8/17 cases). Deletions at 5q, the location of the APC tumour suppressor gene, were seen in three cases. Microsatellite analysis with markers on chromosomal arms 1p, 5q, 8p, 17p, 18q, 19p, and 22q revealed a microsatellite instable phenotype in two cases and a high frequency of loss at 18q21-q22 (80%). Given the high incidence of 18q21-q22 deletions, we performed sequencing analysis of SMAD4, a downstream component of the TGFbeta-pathway, located at 18q21. Four tumours displayed mutations in highly conserved domains of the gene indicating disruption of TGFbeta-signalling. Our data reveal complex genetic alterations in sporadic small intestinal carcinomas. However, most tumours share deletions of 18q21-q22, which frequently target SMAD4. This indicates that disruption of TGFbeta-signalling plays a critical role in small intestinal tumorigenesis.

Topics: Adenocarcinoma; Adult; Aged; Aged, 80 and over; Alleles; Amino Acid Substitution; Cell Transformation, Neoplastic; Chromosome Aberrations; Chromosomes, Human, Pair 18; Chromosomes, Human, Pair 5; Codon; DNA Mutational Analysis; DNA-Binding Proteins; DNA, Neoplasm; Female; Humans; Intestinal Mucosa; Intestinal Neoplasms; Intestine, Small; Loss of Heterozygosity; Male; Microsatellite Repeats; Middle Aged; Mutation, Missense; Neoplasm Proteins; Nucleic Acid Hybridization; Point Mutation; Retrospective Studies; Sequence Deletion; Signal Transduction; Smad4 Protein; Trans-Activators; Transforming Growth Factor beta

Recent investigation suggests that cyclooxygenase-2 plays an important role in colorectal carcinogenesis. Transforming growth factor-beta1 (TGF-beta 1) is one of the most potent stimulators of cyclooxygenase-2 expression. A key step in intestinal tumorigenesis involves alteration of the normal cellular response to TGF-beta 1. We have hypothesized that overexpression of cyclooxygenase-2 alters intestinal epithelial response to TGF-beta 1.. RIE-1 cells were stably transfected with rat cyclooxygenase-2 complementary DNA in either the sense (RIE-S) or antisense (RIE-AS) orientation. Tumor cell invasion was assessed with a modified Boyden collagen type I invasion assay in the presence of TGF-beta 1, antibody to urokinase plasminogen activator (uPA), or the selective cyclooxygenase-2 inhibitor SC-58125. Expression of uPA, uPA receptor, and plasminogen activator inhibitor-1 were determined by Western blot and enzyme-linked immunosorbent assay.. RIE-1 and RIE-AS did not invade although RIE-S cells were minimally invasive at baseline. TGF-beta 1 had no effect on RIE-1 or RIE-AS invasion; however, TGF-beta 1 significantly upregulated RIE-S cell invasion. All 3 RIE cell lines produce minimal uPA under basal conditions. TGF-beta 1 upregulated uPA production only in the RIE-S cells. Both antibody to uPA and SC-58125 reversed TGF-beta-mediated RIE-S cell invasion. SC-58125 inhibited TGF-beta-mediated RIE-S uPA production.. These results demonstrate that overexpression of cyclooxygenase-2 alters intestinal epithelial response to TGF-beta 1, which may be a mechanism by which cyclooxygenase-2 promotes colon carcinogenesis.

Topics: Animals; Cells, Cultured; Cyclooxygenase 2; Intestinal Neoplasms; Isoenzymes; Neoplasm Invasiveness; Prostaglandin-Endoperoxide Synthases; Rats; Transforming Growth Factor beta; Urokinase-Type Plasminogen Activator

Topics: Animals; Disease Progression; DNA-Binding Proteins; Intestinal Neoplasms; Mice; Smad4 Protein; Trans-Activators; Transforming Growth Factor beta

The recent identification and cloning of mammalian transforming growth factor beta (TGFbeta) receptors permits further analysis of the importance of the TGFbeta family in intestinal biology. Expression of the type II TGFbeta receptor was examined in gastrointestinal cell lines and tissues. The 5.5 kb type II mRNA species was detected in poly-(A) mRNA isolated from the rat small bowel and colon. Northern blot analysis of RNA isolated from epithelial and non-epithelial small intestinal cell fractions showed the majority of receptor mRNA localized in the non-epithelial compartment. Immunohistochemical localization in the small intestine and colon supported the RNA findings; that is, expression was greatest in the lamina propria and muscularis. Staining was also detectable in the epithelium, where it was most prominent in the villus tip cells and absent in crypt cells. These findings mirror expression of TGFbeta in the epithelial compartment. The IEC-6, IPEC and RIE-1 cell lines, all of which are non-transformed, were growth inhibited by TGFbeta and expressed type II receptor mRNA and protein. By contrast, the ras-transfected RIE-1, HT-29, Caco-2 and SW-620 transformed lines were not growth inhibited by TGFbeta and all demonstrated a marked reduction in type II TGFbeta receptor mRNA expression and protein abundance by cross-linking. In conclusion, (i) colocalization of both ligand and receptor establishes the existence of potential autocrine and/or paracrine pathways for TGFbeta in the normal intestine and (ii) down-regulation of the type II TGFbeta receptor occurs in association with cellular transformation and may contribute to intestinal carcinogenesis.

Topics: Animals; Cell Line; Cell Line, Transformed; Cell Transformation, Neoplastic; Genes, ras; Intestinal Neoplasms; Intestines; Rats; Receptors, Transforming Growth Factor beta; RNA, Messenger; Transforming Growth Factor beta