Tumor suppressors APC and VHL: gatekeepers of the intestine and kidney.
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Adenomatous Polyposis Coli Protein↗
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A modifying locus for familial adenomatous polyposis may be present on chromosome 1p35-p36.
Mutations of the APC gene cause familial adenomatous polyposis (FAP) in humans and multiple intestinal neoplasia (Min) in laboratory mouse strains. A dominant modifying gene (Mom1), which partially suppresses the min phenotype, has been mapped to mouse chromosome 4. This region is syntenic with human chromosome 1p35-p36. The phospholipase A2 (Pla2s) locus is an excellent candidate for Mom1 and the equivalent human locus PLA2G2A is found on chromosome 1p35. It does not necessarily follow, however, than any modifier of mouse polyposis also influences human disease. In order to test whether a locus on 1p modifies FAP, subjects from 28 FAP families have been typed at microsatellite loci on this chromosome arm. The severity of their duodenal polyposis has also been assessed by endoscopy. Pedigree (lod score) linkage analysis found no evidence of a simple, dominant modifying gene, comparable with the action of Mom1 in inbred mouse strains. Given the more complex genetic and environmental interactions likely to exist in outbred human populations, it is probably more appropriate to use tests which do not specify a mode of inheritance. Using these methods of analysis, the data suggest that a locus on chromosome 1p35-p36 may influence the severity of duodenal FAP.
Adenomatous Polyposis Coli↗
Management of mesenteric desmoid tumours in familial adenomatous polyposis.
Intra-abdominal desmoids are locally invasive fibrous tumours within the mesentery of the intestine. They occur in 4% to 13% of patients with familial adenomatous polyposis (FAP). Of 498 patients registered in the Steve Atanas Stavro FAP Registry at the Mount Sinai Hospital, Toronto, 53 (11%) had desmoids and 40 of them had mesenteric desmoids. There were 23 women and 17 men, and the mean age was 31 years. Most tumours were diagnosed after colectomy for FAP. Of the 40 patients 7 (18%) died of desmoid-related complications. Surgical excision of desmoids is hazardous and was associated with a recurrence rate of up to 85% in this study. Current research is directed at the role of antiestrogens in the fundamental mechanisms of cell growth and are now the subject of clinical trials.
Abdominal Neoplasms↗
Cyclin D1 is not an essential target of beta-catenin signaling during intestinal tumorigenesis, but it may act as a modifier of disease severity in multiple intestinal neoplasia (Min) mice.
Deregulation of beta-catenin activity is an important step in the development of colorectal cancers. One consequence of this is transcriptional activation of cyclin D1, an oncogene known to be overexpressed in colorectal cancers. We tested the hypothesis that cyclin D1 gene activation is important for intestinal tumorigenesis. Multiple intestinal neoplasia mice (a model for human familial adenomatous polyposis) were crossed with cyclin D1 knockout (Ccnd1(-/-)) mice. Despite the absence of cyclin D1, intestinal tumors still developed. However, Ccnd1(-/-) multiple intestinal neoplasia mice developed significantly fewer tumors than Ccnd1(+/-) or Ccnd1(+/+) mice (P = 0.003). We conclude that cyclin D1 is not essential for intestinal tumorigenesis, but it may act as a modifier gene.
Animals↗
Ileal pouch-anal anastomosis: comparison of results in familial adenomatous polyposis and chronic ulcerative colitis.
The aim of this study was to compare the immediate postoperative results and the long-term outcome of ileal pouch-anal anastomosis in 94 patients with familial adenomatous polyposis to those in 758 patients with ulcerative colitis. Two colitis patients died after operation (0.3%), but no polyposis patients died. Overall operative complications appeared in 26% and 29% of polyposis and colitis patients, respectively (NS). Reoperation for intestinal obstruction did not differ between the two groups, but sepsis requiring reoperation was more common in colitis patients (6%) than in polyposis patients (0%, p less than 0.04). At follow-up (mean, 3 years), polyposis patients had fewer daytime stools (4.5 stools per day), less nighttime fecal spotting (26%), and less pouchitis (7%) than colitis patients (5.8 stools per day; spotting, 40%; pouchitis, 22%; p less than 0.002). The conclusion was that polyposis patients tolerated the operation better and had less long-term disability than did colitis patients. The data suggest that postoperative sepsis, daytime stooling frequency, nocturnal incontinence, and pouchitis may be, at least in part, disease related and not surgeon or operation related.
Adenomatous Polyposis Coli↗
Evaluation of 5-aminosalicylic acid (5-ASA) for cancer chemoprevention: lack of efficacy against nascent adenomatous polyps in the Apc(Min) mouse.
Recent experimental and epidemiological evidence suggests that nonsteroidal anti-inflammatory drugs (NSAIDs) are effective in the prevention of colorectal cancer. However, the toxicity associated with the long-term use of most classical NSAIDs has limited their usefulness for the purpose of cancer chemoprevention. Inflammatory bowel disease (IBD) patients, in particular, are sensitive to the adverse side effects of NSAIDs, and these patients also have an increased risk for the development of intestinal cancer. 5-Aminosalicylic acid (5-ASA) is an anti-inflammatory drug commonly used in the treatment of IBD and may provide protection against the development of colorectal cancer in these patients. To directly evaluate the ability of 5-ASA to suppress intestinal tumors, we studied several formulations of 5-ASA (free acid, sulfasalazine, and Pentasa) at multiple oral dosage levels [500, 2400, 4800, and 9600 parts/million (ppm)] in the adenomatous polyposis coli (Apc) mouse model of multiple intestinal neoplasia (Min). Although the ApcMin mouse is not a model of colitis-associated neoplasia, it is, nonetheless, a useful model for assessing the ability of anti-inflammatory agents to prevent tumor formation in a genetically preinitiated population of cells. We used a study design in which drug was provided ad libitum through the diet beginning at the time of weaning (28 days of age) until 100 days of age. We included 200 ppm of piroxicam and 160 ppm of sulindac as positive controls, and the negative control was AIN-93G diet alone. Treatment with either piroxicam or sulindac produced statistically significant reductions in intestinal tumor multiplicity (95% and 83% reductions in tumor number, respectively; P < 0.001 versus controls). By contrast, none of the 5-ASA drug formulations or dosage levels produced consistent dose-progressive changes in polyp number, distribution, or size, despite high luminal and serum concentrations of 5-ASA and its primary metabolite N-acetyl-5-ASA. Thus, 5-ASA does not seem to possess direct chemosuppressive activity against the development of nascent intestinal adenomas in the ApcMin mouse. However, because intestinal tumor development in the ApcMin mouse is driven by a germline mutation in the Apc gene rather than by chronic inflammation, we caution that these findings do not definitively exclude the possibility that 5-ASA may exert a chemopreventive effect in human IBD patients.
Adenomatous Polyps↗
Nuclear accumulation of beta-catenin in intestinal-type gastric carcinoma: correlation with early tumor invasion.
Mutation of the adenomatous polyposis coli gene, which is known to be an early event in the carcinogenesis of intestinal-type gastric carcinoma, leads to accumulation of beta-catenin. In addition, beta-catenin has been found to activate down stream signaling molecules in the wingless/Wnt pathway. In this study, the clinical significance of nuclear accumulation of beta-catenin was evaluated in gastric carcinoma. Immunohistochemical staining showed nuclear localization in 16 (12%) of 139 (94 intestinal-type and 45 diffuse-type) gastric carcinomas, and all 16 lesions with nuclear staining were intestinal-type adenocarcinomas. Of the 16 cases, 15 were in the early clinical stage. In the remaining case, the lesion had invaded the subserosal layer and showed strong nuclear staining at the invasive front. In 14 of the 16 cases with nuclear localization, there were no abnormal mobility shifts detected using polymerase chain reaction-single strand conformational polymorphism analysis. This was confirmed using direct sequencing analysis, which revealed the wild-type sequence in the 12 cases tested. Nuclear accumulation of beta-catenin did not correlate with lymph node metastasis or 5-year survival. These findings suggest that high intranuclear levels of beta-catenin protein play an important role in early tumor growth and may function in initiation of invasive processes in intestinal-type gastric carcinoma.
Adenocarcinoma↗
Transcriptional profiles of intestinal tumors in Apc(Min) mice are unique from those of embryonic intestine and identify novel gene targets dysregulated in human colorectal tumors.
The adenomatous polyposis coli (APC) tumor suppressor is a major regulator of the Wnt signaling pathway in normal intestinal epithelium. APC, in conjunction with AXIN and GSK-3beta, forms a complex necessary for the degradation of beta-catenin, thereby preventing beta-catenin/T-cell factor interaction and alteration of growth-controlling genes such as c-MYC and cyclin D1. Inappropriate activation of the Wnt pathway, via Apc/APC mutation, leads to gastrointestinal tumor formation in both the mouse and human. In order to discover novel genes that may contribute to tumor progression in the gastrointestinal tract, we used cDNA microarrays to identify 114 genes with altered levels of expression in Apc(Min) mouse adenomas from the duodenum, jejunum, and colon. Changes in the expression of 24 of these 114 genes were not observed during mouse development at embryonic day 16.5, postnatal day 1, or postnatal day 14 (relative to normal adult intestine). These 24 genes are not previously known Wnt targets. Seven genes were validated by real-time reverse transcription-PCR analysis, whereas four genes were validated by in situ hybridization to mouse adenomas. Real-time reverse transcription-PCR analysis of human colorectal cancer cell lines and adenocarcinomas revealed that altered expression levels were also observed for six of the genes Igfbp5, Lcn2, Ly6d, N4wbp4 (PMEPA1), S100c, and Sox4.
Adenoma↗
Thrombospondin 1--a regulator of adenoma growth and carcinoma progression in the APC(Min/+) mouse model.
Thrombospondin 1 (TSP-1) is a multifunctional extracellular matrix protein that is an endogenous regulator of tumor angiogenesis. The effects of TSP-1 on adenoma formation and development into cancerous lesions has been evaluated in the Min(/+) (multiple intestinal neoplasia) mouse model. These mice develop multiple adenomas in the small intestine due to a mutation in the homologous APC (adenomatous polyposis coli) gene. As in its human counterpart, these adenomas may progress to carcinomas. Intestines of APC(Min/+) mice were dissected and histologic evaluation of adenomas was then conducted. Significant increases in vascularization and proliferation were observed in adenomatous, as compared with normal, mucosa. TSP-1 immunostaining revealed significant decreases in the number and intensity of positive cells in adenomas, as compared with normal mucosa. TSP-1 scores were inversely correlated with vascularity and proliferation rate. Cross breeding of mice homozygous for a deletion of the TSP-1 gene (TSP-1(-/-)) with mice heterozygous for the APC gene mutation (APC(Min/+)), resulted in animals that showed a significant increase in adenoma number and diameter. Also, histopathological examination of these adenomas showed accelerated dysplasic changes, carcinoma in situ and early invasion, compared with their APC(Min/+) littermates. Moreover, a significant decrease of TUNEL-positive cells was observed in intestinal adenomas of TSP-1(-/-)/APC(Min/+) mice. This study reports the first in vivo impact of TSP-1 during early stages of tumor initiation and development in an intestinal carcinogenesis model and demonstrates that TSP-1 affects both angiogenesis and tumor cell apoptosis.
Adenoma↗
Intestinal immune responses in wild-type and Apcmin/+ mouse, a model for colon cancer.
C57BL/6J Apc(Min/+) (Apc(Min/+)) mice spontaneously develop pretumoric adenomas into the intestinal mucosa. We studied the relationship between the intestinal immune responses and adenoma formation in Apc(Min/+) mice and compared Apc(Min/+) mice with their wild-type siblings. Three time points (5, 8, and 15 weeks of age) and three high-fat dietary treatments (a non-fiber control with beef or inulin amendment) were included. The numbers of CD8+ T lymphocytes and tissue macrophages (Mac-1+ cells) per villus in ileal mucosa were determined by immunohistology, and the concentrations of secretory IgA, residual prostaglandin E(2) (PGE(2)), tumor necrosis factor alpha, and interleukin (IL)-12 in ileal contents were analyzed by ELISA. The crypt-villus ratio of the ileal mucosa was determined histologically. An immunostimulation, characterized by an increase in several parameters (PGE(2), IgA, Mac-1, and CD8), was observed in both genotypes between weeks 5 and 8. Most of the adenomas in Apc(Min/+) mice also appeared during the same period of sexual maturation. Females had smaller adenomas than males, and the beef group had fewer and smaller adenomas than the control group at 15 weeks. Females had less IgA and fewer Mac-1+ and CD8+ cells in ileal tissue than males at 15 weeks and more luminal IL-12 than males at 8 weeks. Puberty may have affected both tumorigenesis and intestinal immune responses in the Apc(Min/+) mouse. The beef group showed less luminal IgA and tumor necrosis factor alpha but more IL-12 than the control group. The concentration of PGE(2) correlated positively with the number and size of adenomas and was higher in the Apc(Min/+) mice than in wild-type mice at 15 weeks. IgA and Mac-1 were positively correlated with the size of adenomas at 15 weeks. The positive correlations between tumor size and IgA and between tumor number and size and PGE(2) suggest that a balance toward the Th2 type immune response may affect the pace of tumorigenesis in this model. The general similarity of the intestinal immune responses in both genotypes and the lack of intestinal inflammation in the Apc(Min/+) mice suggest that the mutation in the adenomatous polyposis coli gene does not lead to major alterations in intestinal immune function and that the intestinal immunology does not explain tumorigenesis in the Apc(Min/+) mouse model.
Adenoma↗
Evidence against dominant negative mechanisms of intestinal polyp formation by Apc gene mutations.
Mutations in the adenomatous polyposis coli (APC) gene are responsible for not only familial adenomatous polyposis but also many sporadic cancers of the digestive tract. Most mutations found in familial adenomatous polyposis patients are of the truncation type, and the phenotype is affected by the mutation sites in the gene. Truncated APC proteins can associate with the wild-type protein. Accordingly, it has been proposed that the polyposis is caused by a dominant negative mechanism. To test this possibility, we constructed transgenic mice that contained mutant minigenes. They expressed the APC protein truncated either at codon 716 (Apc delta 716) or 1287 (Apc delta 1287) at high levels in the intestinal epithelium. Contrary to our expectation, no intestinal polyps or tumors were found in any of such mice, even after 7 months. These results rule out any dominant negative mechanisms in which the truncated APC protein is directly involved in the formation of intestinal polyps in the mouse.
Adenomatous Polyposis Coli Protein↗
Loss of Apc heterozygosity and abnormal tissue building in nascent intestinal polyps in mice carrying a truncated Apc gene.
Mutations in the APC (adenomatous polyposis coli) gene appear to be responsible for not only familial adenomatous polyposis but also many sporadic cases of gastrointestinal cancers. Using homologous recombination in mouse embryonic stem cells, we constructed mice that contained a mutant gene encoding a product truncated at a 716 (Apc delta 716). Mendelian transmission of the gene caused most homozygous mice to die in utero before day 8 of gestation. The heterozygotes developed multiple polyps throughout the intestinal tract, mostly in the small intestine. The earliest polyps arose multifocally during the third week after birth, and new polyps continued to appear thereafter. Surprisingly, every nascent polyp consisted of a microadenoma covered with a layer of the normal villous epithelium. These microadenomas originated from single crypts by forming abnormal outpockets into the inner (lacteal) side of the neighboring villi. We carefully dissected such microadenomas from nascent polyps by peeling off the normal epithelium and determined their genotype by PCR: all microadenomas had already lost the wild-type Apc allele, whereas the mutant allele remained unchanged. These results indicate that loss of heterozygosity followed by formation of intravillous microadenomas is responsible for polyposis in Apc delta 716 intestinal mucosa. It is therefore unlikely that the truncated product interacts directly with the wild-type protein and causes the microadenomas by a dominant negative mechanism.
Adenoma↗
Gastric adenomas: intestinal-type and gastric-type adenomas differ in the risk of adenocarcinoma and presence of background mucosal pathology.
Gastric adenomas are neoplastic growths characterized by localized, polypoid proliferations of dysplastic epithelium. They frequently arise in stomachs with a background of mucosal atrophy and intestinal metaplasia, and a higher risk of adenocarcinoma elsewhere in the stomach has been reported in patients with gastric adenomas. Additionally, some gastric adenomas themselves demonstrate neoplastic progression to infiltrating adenocarcinoma. However, previous studies have not comprehensively evaluated the background gastric mucosa and risk of adenocarcinoma, particularly in relation to the histologic classification of adenomas as either intestinal-type or gastric-type. We studied 61 gastric adenomas from 51 patients between 1985 and 2001. The adenomas were classified as intestinal-type (containing at least focal goblet cells and/or Paneth cells), gastric-type (lined entirely by gastric mucin cells on PAS/alcian blue stain), or indeterminate. We evaluated the histologic features of both the adenomas (location, multiplicity, degree of dysplasia, presence of adenocarcinoma within the polyp) and the surrounding gastric mucosa (presence of gastritis, intestinal metaplasia, and adenocarcinoma). Gastric adenomas were distributed equally throughout the stomach, were most frequently solitary (82%), and contained adenocarcinoma in nine cases (14.8%). There were 34 intestinal-type adenomas (56%) in 31 patients, 25 gastric-type adenomas (41%) in 18 patients (including 10 patients with familial adenomatous polyposis), and 2 of indeterminate type (3%). Intestinal-type adenomas were significantly more likely than gastric-type adenomas to show high-grade dysplasia (p <0.0001), adenocarcinoma within the polyp (p = 0.016), intestinal metaplasia in the surrounding stomach (p <0.000001), and gastritis (p = 0.002). Patients with intestinal-type adenomas were also more likely to have separate adenocarcinomas (five cases vs 0 cases), although this did not reach statistical significance. Gastric adenomas are rarely truly "sporadic" lesions. In any individual patient complete removal of the adenoma should be performed, and thorough biopsy of the surrounding gastric mucosa is essential to understand the clinicopathologic context of the adenoma.
Adenoma↗
Paneth cell adenoma of the ileum.
A Paneth cell adenoma of the ileum was recently found in a 47-year-old male with familial adenomatous polyposis (FAP). The patient had years previously been subjected to a total proctocolectomy. Following surgery, endoscopical biopsies were obtained from the duodenum (10 biopsies) in four instances and from the ileal pouch (6 biopsies) in three. All biopsies were taken between 1988 and 2003. Hematoxylin and eosin (H&E) sections from all those 16 biopsies were reviewed. In one biopsy from the ileal pouch, a tubular adenoma carrying 92% dysplastic Paneth cells was found. Paneth cells were more easily singled out when H&E sections were observed in a fluorescent microscope than when using conventional transmitted light, or lysozyme immunostain. Despite a wide distribution of Paneth cells in mucosas with intestinal metaplasia (e.g. Barrett's esophagus and gastric intestinal metaplasia), in the normal small intestine and in the large intestine with chronic inflammatory diseases only a few Paneth cell neoplasias have been reported in the GI tract. The cause of the apparent natural resistance of these specialized cells provided with anti-microbial and growth factors to undergo neoplastic transformation deserve further investigation. A review of the literature indicates that this is the first reported case of Paneth cell adenoma of the small intestine.
Adenomatous Polyposis Coli↗
Gastroduodenal and ileal polyps in patients treated surgically for familial polyposis coli with proctocolectomy and continent ileostomy.
Eighteen patients, who previously had been treated surgically for familial polyposis coli with proctocolectomy and a continent ileostomy were re-investigated with endoscopy and X-ray for gastric, duodenal and ileal polyps. Gastric and/or duodenal polyps were found in 6 patients and ileal polyps in 2. Altogether upper GI-polyps were found in 7 patients (39%). Most polyps were true adenomas. In one patient with large gastric adenomas, the severe dysplasia called for a gastric resection. It is obvious that familial polyposis may affect the whole gastro-intestinal tract, therefore necessitating regular surveillance of the upper GI-canal as well as the colon and rectum in patients with this hereditary affliction.
Adenomatous Polyposis Coli↗
Insulin-like growth factor II supply modifies growth of intestinal adenoma in Apc(Min/+) mice.
Insulin-like growth factor-II (IGF-II) is an embryonic growth promoter and cell survival factor. IGF-II supply is normally limited by gene expression because transcription occurs predominantly from the paternal allele in mouse and man (maternal imprinting). Excess IGF-II has detrimental systemic and local effects in vivo, promoting somatic overgrowth and an increased frequency of tumors. IGF2 mRNA is overexpressed in colorectal and many other human cancers. In this paper, we show that altered IGF-II supply modifies intestinal tumor growth. Mice genetically altered in the IGF-II system were combined in crosses with ApcMin/+, a murine model of human familial adenomatous polyposis. Depending on genetic background, ApcMin/+ acquires multiple small intestinal adenoma before becoming moribund with anemia. Mice that express excess IGF-II delivered using a bovine keratin 10 promoter (k10Igf2/+) develop a disproportionate overgrowth of colon, uterus, and skin. Combination with ApcMin/+ leads to a 10-fold increase in the number and the diameter of colon adenoma (P<0.0001) compared to ApcMin/+ littermate controls (postnatal day 80), an increased susceptibility to rectal prolapse (41%), and a histological progression to carcinoma. Mice with reduced IGF-II supply, secondary to the disruption of the paternal Igf2 allele (Igf2+m/-p), are 60% the weight of wild-type littermates. Combination with ApcMin/+ leads to a 3-fold reduction in small intestinal adenoma number (P<0.0001) compared to ApcMin/+ littermate controls (postnatal day 150), and a significant decrease in adenoma diameter (P<0.001). With in situ hybridization, we show that Igf2 was expressed in all adenoma irrespective of IGF-II supply. This suggests that there is an increased maternal allele expression of Igf2 (loss of imprinting) in adenoma which form, despite paternal Igf2 allele disruption. We conclude that IGF-II supply is a modifier of intestinal adenoma growth, and we provide genetic evidence for its functional role in colorectal cancer progression.
Adenoma↗
Abstracts from the Third Meeting of the Leeds Castle Polyposis Group. 15-17 June 1989.
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Adenomatous Polyposis Coli↗
Extra-abdominal desmoid fibromatosis: two familial cases with synchronous and metachronous multicentric hyalinizing nodules.
AIMS: Extra-abdominal desmoid fibromatosis is an uncommon tumour. We present here two exceptional familial cases of extra-abdominal desmoid fibromatosis, one of which was synchronous and metachronous. METHODS AND RESULTS: The first patient was a 37-year-old woman who had noted a tumour growing on the dorsum of her right foot when she was 12 years old. She underwent excision of the tumour but in the following year the tumour recurred locally and grew into multiple nodules. Subsequently, multicentric tumours appeared in her knee, distal and posterior aspects of her thigh, right back and right anterior shoulder. Polyostotic fibrous dysplasia of the femur and cranium was found on radiological examination. The second patient was a 74-year-old man, the uncle of the first patient. He underwent an excisional operation of a tumour on the internal malleolus surface of his fibula when he was 46 years old. The tumour recurred 7 years later and was excised. His post-operative course has been uneventful. The histology of the primary and recurrent tumours was distinctive and consistently showed hyalinizing scar-like features. CONCLUSIONS: Familial cases of extra-abdominal desmoid fibromatosis with extensive multicentric lesions and distinctive hyalinizing scar-like features are described. Recently, attenuated familial adenomatous polyposis with familial desmoid fibromatosis has been recognized, and familial desmoid fibromatosis without adenomatous polyposis may also be one of its variants. Although the present cases have no history of colon polyposis or carcinoma, monitoring of the intestinal tract would seem to be indicated.
Adult↗