Project description:Colorectal cancer (CRC) is a leading cause for cancer related mortality in the western world with a lifetime risk of 6%. Etiology is complex, while genetic background significantly affects the risk. Around one third of all genetic disorders as well as most cases of Familial Adenomatous Polyposis (FAP) and a large proportion of all sporadic CRC cases occur as a result of premature nonsense mutations (creating a stop codon) in an individual’s adenomatous polyposis coli (APC) gene. Nonsense mutations are single-point alterations in the DNA that prematurely halt the protein translation process, producing a shortened, nonfunctional protein. In many of these cases, if the cell can be ‘persuaded’ to ignore the premature stop codon signal, the resulting protein may be able to ameliorate or stop the disease. Recently, members of the aminoglycoside family of antibiotics have been found to induce ribosomal read-through of nonsense mutations, leading to expression of a full length, functional protein. Investigators have recently shown that members of the aminoglycoside and macrolide antibiotic families can induce read-through of the nonsense mutations in the APC gene and lead to reduced oncogenic phenotypes in CRC cells and in different mice models. The aim of this project is to determine the ability of the macrolide antibiotic-erythromycin to induce read-through of the nonsense mutations in the APC gene and to induce expression of a full length, functional APC protein in patients suffering from FAP and to tests its effect on adenoma number and size and on desmoid tumors in these patients. The future goal is to maximize the effect of stop-codon suppressors on APC while minimizing side effects. In this study investigators will select FAP patients which carry APC nonsense mutations, treat them with erythromycin PO for 4-6 months and examine colonic and duodenal adenomas as well as abdominal desmoid tumors, that will be documented before during and after treatment. In parallel, investigators will test polyp, adenoma and desmoid tissue samples as well as blood samples from these patients for changes in expression levels of the APC protein and related oncogenic markers. Suppression of nonsense mutations within the APC gene should be of benefit for patients suffering from FAP, attenuated FAP or multiple adenomas and for patients with advanced or diffuse CRC. Furthermore, given the rapid progress being made in the identification of different nonsense mutations in human genes that lead to mostly un-curable disease, the identification of clinically approved compounds that suppress nonsense mutations and that can be administered long-term without significant side effects would open new venues in the treatment of genetic human diseases that arise from pre-mature stop codons in important coding sequences. Immediate goal: establish the ability of erythromycin to read-through APC nonsense mutation in FAP patients. The read-through effect of erythromycin will be clinically tested by counting and measuring the number and size of both colonic and duodenal adenomas before and over treatment and by measuring the size of known desmoid tumors. Samples of the adenomas and desmoid tumors will be tested by western blot, immunofluorescence and immunohistochemistry for restoration of APC expression and changes in oncogenic markers. These experiments should be conducted within 6 month. Long term objective: 1. Determine the lowest dose of erythromycin that can inhibit growth of colonic neoplasia and CRC in patients expressing a truncated APC protein due to nonsense mutations. 2. Examine the ability of a panel of additional macrolide antibiotics to induce APC nonsense mutation suppression using in-vitro methods. Investigators will focus on macrolide antibiotics that are currently in clinical use and are administrated for long terms. These objectives should take around 6 month and will be conducted in parallel.

Project description:Desmoid tumors (also called deep or aggressive fibromatoses) are potentially life-threatening fibromatous lesions. Hereditary desmoid tumors arise in individuals affected by either familial adenomatous polyposis (FAP) or hereditary desmoid disease (HDD) carrying germline mutations in APC. Most non-FAP (sporadic) desmoids carry somatic mutations in the beta-catenin gene. Previous studies identified losses on 5q and 6q, and gains on 8q and 20q as recurrent genetic changes in desmoids. However, virtually all genetic changes were derived from sporadic tumors. To investigate the somatic alterations in FAP-associated desmoids and to compare them with changes occurring in sporadic tumors, we analyzed 17 FAP-associated and 38 sporadic desmoids for copy number abnormalities (CNAs) by means of array comparative genomic hybridization and multiple ligation-dependent probe amplification. Overall, the desmoids displayed only a limited number of genetic changes, occurring in 44% of cases. Common gains at 8q (7%) and 20q (5%) were almost exclusively found in sporadic tumors. Frequent common losses were observed within a 700 kb region at 5q22.2, comprising the APC gene (11%), in a 2 Mb region at 6p21.2-p21.1 (15%), and in a relatively large region at 6q15-q23.3 (20%). The FAP-associated desmoids displayed a significantly higher frequency of CNAs (59%) than the sporadic tumors (37%). As predicted by the APC germline mutations among these patients, a relatively high percentage (29%) of the FAP-associated desmoids showed loss of the APC region at 5q22.2, which was infrequently (3%) seen among sporadic tumors. Our data suggest that loss of region 6q15-q16.2 is an important event in FAP-associated as well as sporadic desmoids, most likely of relevance for desmoid tumor progression. Fifty-three fresh frozen tumor samples were collected at four institutes: Center for Human Genetics, University of Leuven, Belgium (21 samples); INSERM U674, Fondation Jean Dausset-CEPH, Paris, France (15 samples); Hospital for Sick Children, Toronto, Canada (13 samples); and the Italian Registry of Hereditary Colorectal Cancer (Dr. L. Bertario, 4 samples). In addition, DNA of two fresh frozen tumors, HDD-H of patient III:2 and HDD-I of patient III:6, of our hereditary desmoids disease (HDD) family10 was available (Table 1). In this family, multifocal desmoid tumors were inherited as an autosomal dominant trait, and HDD segregated with a 3' APC mutation at codon 1924. For the latter reason, they were classified as FAP tumors in this study. Three FAP tumors were derived from a family with 2 relatives in the study (D15-1 and D15-2 of a male patient and D16 of his sister). Colonic polyposis had been observed in 12 FAP patients, not in the 2 HDD-FAP patients and not in patient D15. The germline APC mutation was known in 14 of 17 FAP-associated tumors. In 28 of 38 non-FAP-associated desmoid tumors, the beta-catenin gene (CTNNB1) mutation in exon 3 was known and in 1 of 38 tumors an APC mutation was present (data not shown). The remaining tumors were characterized as FAP or non-FAP based on clinical data and positivity of tumor cells upon immunostaining for beta-catenin. DNA was extracted from the tumor samples according to standard methods.

Project description:Expression profiling is a well established tool for the genome-wide analysis of the transcriptional activity of human neoplasia. However, the high sensitivity of this approach combined with the well-known cellular and molecular heterogeneity of cancer often result in extremely complex and extended expression signatures of difficult functional interpretation. The majority of sporadic colorectal cancer cases are triggered by mutations in the APC tumor suppressor gene leading to constitutive activation of the Wnt/b-catenin signaling pathway and adenoma formation. Notwithstanding this common genetic basis, colorectal cancers are very heterogeneous in their degree of differentiation, growth rate and malignant potential. Here, we applied cross-species comparison of expression profiles of intestinal polyps derived from hereditary colorectal cancer patients carrying APC germline mutations, and from a mouse model carrying a targeted inactivating mutation in the mouse homologue Apc. This comparative approach resulted in the establishment of a conserved signature encompassing 166 genes differentially expressed between adenomas and normal intestinal mucosa in both species. Functional analysis of the conserved genes revealed a general increase in cell proliferation and the activation of the Wnt/b-catenin signal transduction pathway, as expected from the selection of APC/Apc-mutant intestinal adenomas. Moreover, the conserved signature is able to resolve expression profiles from hereditary polyposis patients carrying APC germline mutations from those with bi-allelic incativation of the MYH gene. Keywords: normal versus tumor comparison; compare expression profiles from microdissected samples with distinct germline mutations (FAP vs. MAP). Here, we report the expression profiles from normal and intestinal adenomatous tissue from FAP (familial adenomatous polyposis) and MAP (MUTY-associated polyposis) patients with established APC and MUTY germline mutations. Total RNA samples were obtianed by laser capture microdissection.

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Azithromycin Treatment for Readthrough of APC Gene Stop Codon Mutations in Familial Adenomatous Polyposis

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