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Gan WJ, Giri R, Begun J, Abud HE, Hardeman EC, Gunning PW, Yap AS, Noordstra I. A truncation mutant of adenomatous polyposis coli impairs apical cell extrusion through elevated epithelial tissue tension. Cytoskeleton (Hoboken) 2024. [PMID: 38984538 DOI: 10.1002/cm.21893] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2024] [Revised: 05/21/2024] [Accepted: 06/27/2024] [Indexed: 07/11/2024]
Abstract
Tissue tension encompasses the mechanical forces exerted on solid tissues within animal bodies, originating from various sources such as cellular contractility, interactions with neighboring cells and the extracellular matrix. Emerging evidence indicates that an imbalance in such forces can influence structural organization, homeostasis, and potentially contribute to disease. For instance, heightened tissue tension can impede apical cell extrusion, leading to the retention of apoptotic or transformed cells. In this study, we investigate the potential role of adenomatous polyposis coli (APC) in modulating tissue tension. Our findings reveal that expression of an APC truncation mutant elevates epithelial tension via the RhoA/ROCK pathway. This elevation induces morphological alterations and hampers apoptotic cell extrusion in cultured epithelial cells and organoids, both of which could be mitigated by pharmacologically restoring the tissue tension. This raises the possibility that APC mutations may exert pathogenetic effects by altering tissue mechanics.
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Affiliation(s)
- Wan J Gan
- Centre for Cell Biology of Chronic Disease, Institute for Molecular Bioscience, The University of Queensland, St Lucia, Queensland, Australia
| | - Rabina Giri
- Mater Research Institute, The University of Queensland, Translational Research Institute, Woolloongabba, Queensland, Australia
- Faculty of Medicine, The University of Queensland, St. Lucia, Queensland, Australia
| | - Jakob Begun
- Mater Research Institute, The University of Queensland, Translational Research Institute, Woolloongabba, Queensland, Australia
- Faculty of Medicine, The University of Queensland, St. Lucia, Queensland, Australia
| | - Helen E Abud
- Department of Anatomy and Developmental Biology, Development and Stem Cells Program, Biomedicine Discovery Institute, Monash University, Clayton, Victoria, Australia
| | - Edna C Hardeman
- Faculty of Medicine and Health, School of Biomedical Sciences, University of New South Wales, Sydney, New South Wales, Australia
| | - Peter W Gunning
- Faculty of Medicine and Health, School of Biomedical Sciences, University of New South Wales, Sydney, New South Wales, Australia
| | - Alpha S Yap
- Centre for Cell Biology of Chronic Disease, Institute for Molecular Bioscience, The University of Queensland, St Lucia, Queensland, Australia
| | - Ivar Noordstra
- Centre for Cell Biology of Chronic Disease, Institute for Molecular Bioscience, The University of Queensland, St Lucia, Queensland, Australia
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Cai B, Liu Z, Xu Y, Wei W, Zhang S. Adenoma detection rate in 41,010 patients from Southwest China. Oncol Lett 2015; 9:2073-2077. [PMID: 26137015 DOI: 10.3892/ol.2015.3005] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2014] [Accepted: 02/13/2015] [Indexed: 12/14/2022] Open
Abstract
Adenoma detection rate (ADR) is considered as an important predictor of the risk of interval colorectal cancer following a screening colonoscopy. A retrospective review of all the patients who underwent colonoscopy in the First Affiliated Hospital of Guangxi Medical University (Nanning, China) between 2003 and 2012 was performed, with the aim of estimating the ADR in Southwest China and determine the effects of age, gender and polyp location on ADR. Demographic information and data regarding the timing of the colonoscopy, number of polyps removed, polyp location and pathological types of polyps were collected and analyzed. The patients were grouped according to colonoscopy date, polyp location, gender and age. The χ2 test was used to compare the ADR between the different age and gender groups and the Cochran-Armitage trend test was used to calculate the statistical significance of the ADR trend across age groups. A two-tailed value of P<0.05 was considered to indicate statistically significant differences. A total of 41,010 patients were included, of whom 7,219 were diagnosed with at least one adenoma on pathological examination. Therefore, the ADR value of the 41,010 patients screened in the present study was 17.6%. There was a statistically significant trend of increasing ADR with increasing age in both genders (P<0.05). In addition, the ADR of male patients was significantly higher compared with that of female patients in all age groups (all P<0.05). The ADR of patients aged >50 years was significantly higher compared with that of patients aged <50 years (28.8 vs. 11.0%, respectively; P<0.05). In addition, 20% of the cases of detected adenomas occurred in the rectum, 47% in the left colon and 33% in the right colon.
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Affiliation(s)
- Bin Cai
- Department of Colorectal Surgery, The First Affiliated Hospital of Guangxi Medical University, Nanning, Guangxi 530021, P.R. China
| | - Zhixian Liu
- Department of Colorectal Surgery, The First Affiliated Hospital of Guangxi Medical University, Nanning, Guangxi 530021, P.R. China
| | - Yansong Xu
- Department of Emergency Surgery, The First Affiliated Hospital of Guangxi Medical University, Nanning, Guangxi 530021, P.R. China
| | - Weiyuan Wei
- Department of Gastrointestinal Surgery, The First Affiliated Hospital of Guangxi Medical University, Nanning, Guangxi 530021, P.R. China
| | - Sen Zhang
- Department of Colorectal Surgery, The First Affiliated Hospital of Guangxi Medical University, Nanning, Guangxi 530021, P.R. China
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Telikicherla D, Maharudraiah J, Pawar H, Marimuthu A, Kashyap MK, Ramachandra YL, Roa JC, Pandey A. Overexpression of Kinesin Associated Protein 3 (KIFAP3) in Breast Cancer. JOURNAL OF PROTEOMICS & BIOINFORMATICS 2012; 5:122-126. [PMID: 26843789 PMCID: PMC4734396 DOI: 10.4172/jpb.1000223] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Gene expression profiling studies on breast cancer have generated catalogs of differentially expressed genes. However, many of these genes have not been investigated for their expression at the protein level. It is possible to systematically evaluate such genes in a high-throughput fashion for their overexpression at the protein level using breast cancer tissue microarrays. Our strategy involved integration of information from publicly available repositories of gene expression to prepare a list of genes upregulated at the mRNA level in breast cancer followed by curation of the published literature to identify those genes that were not tested for overexpression at the protein level. We identified Kinesin Associated Protein 3 (KIFAP3) as one such molecule for further validation at the protein level. Immunohistochemical labeling of KIFAP3 using breast cancer tissue microarrays revealed overexpression of KIFAP3 protein in 84% (240/285) of breast cancers indicating the utility of our integrated approach of combining computational analysis with experimental biology.
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Affiliation(s)
- Deepthi Telikicherla
- Institute of Bioinformatics, International Tech Park, Bangalore-560 066, India
- Department of Biotechnology, Kuvempu University, Shankaraghatta-577451, India
| | - Jagadeesha Maharudraiah
- Institute of Bioinformatics, International Tech Park, Bangalore-560 066, India
- Department of Pathology, Raja Rajeshwari Medical College and Hospital, Bangalore-560074, India
- Manipal University, Madhav Nagar, Manipal-576104, India
| | - Harsh Pawar
- Institute of Bioinformatics, International Tech Park, Bangalore-560 066, India
- Rajiv Gandhi University of Health Sciences, Bangalore-560041, India
- Department of Pathology, Kidwai Memorial Institute of Oncology, Bangalore-560029, India
| | | | - Manoj Kumar Kashyap
- Institute of Bioinformatics, International Tech Park, Bangalore-560 066, India
| | - Y. L. Ramachandra
- Department of Biotechnology, Kuvempu University, Shankaraghatta-577451, India
| | - Juan Carlos Roa
- Department of Pathology, Universidad de La Frontera, Temuco, Chile
| | - Akhilesh Pandey
- McKusick-Nathans Institute of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
- Departments of Biological Chemistry, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
- Department of Pathology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
- Department of Oncology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
- Corresponding author: Akhilesh Pandey M.D., Ph.D., McKusick-Nathans Institute of Genetic Medicine, 733 N. Broadway, BRB 527, Johns Hopkins University, Baltimore, MD 21205, USA, Tel: 410-502-6662; Fax: 410-502-7544;
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Siriwardena BSMS, Kudo Y, Ogawa I, Tilakaratne WM, Takata T. Aberrant beta-catenin expression and adenomatous polyposis coli gene mutation in ameloblastoma and odontogenic carcinoma. Oral Oncol 2008; 45:103-8. [PMID: 18486530 DOI: 10.1016/j.oraloncology.2008.03.008] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2008] [Revised: 04/06/2008] [Accepted: 03/06/2008] [Indexed: 10/22/2022]
Abstract
The Wnt pathway is involved in carcinogenesis and three regulatory genes of the Wnt pathway, APC (adenomatous polyposis coli), beta-catenin and Axin are frequently mutated in some primary human cancers. This study was conducted to clarify the relation of beta-catenin accumulation and the mutation of the CTNNB1 (beta-catenin) gene with the mutation of APC gene in the process of development of odontogenic tumors including ameloblastoma and odontogenic carcinoma (OC). beta-Catenin accumulation was examined by immunohistochemistry in formalin-fixed, paraffin-embedded samples of six ameloblastomas and eight OCs. We also performed a mutation analysis of CTNNB1 and APC to examine the cause of beta-catenin accumulation. All ameloblastoma cases and six out of eight (75%) OC cases exhibited beta-catenin accumulation in the nucleus. CTNNB1 mutation was only found in one OC case, whereas three of six (50%) ameloblastoma cases and two out of eight (25%) OC cases had APC mutations within the mutational cluster region. Our findings suggest that aberrant beta-catenin expression and APC missense mutation may play an important role for the pathogenesis of epithelial odontogenic tumors.
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Affiliation(s)
- B S M S Siriwardena
- Department of Oral Maxillofacial Pathobiology, Division of Frontier Medical Science, Graduate School of Biomedical Sciences, Hiroshima University, Hiroshima 734-8553, Japan
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Ismail SIMF, Bennett SJ. Pregnancy and mode of delivery in patients with familial polyposis. J OBSTET GYNAECOL 2007; 27:200-1. [PMID: 17454482 DOI: 10.1080/01443610601138018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Affiliation(s)
- S I M F Ismail
- Department of Obstetrics and Gynaecology, North Devon District Hospital, Barnstaple, Devon, UK.
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Gupta C, Mazzara PF. High-Grade Pancreatic Intraepithelial Neoplasia in a Patient With Familial Adenomatous Polyposis. Arch Pathol Lab Med 2005; 129:1398-400. [PMID: 16253018 DOI: 10.5858/2005-129-1398-hpinia] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Abstract
Familial adenomatous polyposis (FAP) is caused by mutation of the adenomatous polyposis coli (APC) gene and is characterized by multiple colorectal adenomas and tumors of other organs and sites. A 58-year-old woman with FAP syndrome and previous total colectomy presented for routine follow-up examination. Abdominal ultrasound and subsequent endoscopic evaluation revealed ampullary and duodenal polyps, as well as inhomogeneity of the pancreatic head. A pancreaticoduodenectomy confirmed multiple duodenal adenomas. In addition, high-grade pancreatic intraepithelial neoplasia (PanIN-3) was found in the smaller pancreatic ducts. Pancreatic precancerous lesions have only rarely been described in FAP, including 2 pancreatic duct adenomas and 2 intraductal papillary mucinous neoplasms. A review of the world English literature revealed no reports of PanIN-3 in association with FAP. Further studies are required to determine if patients with FAP are at increased risk for pancreatic premalignant lesions.
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Affiliation(s)
- Chakshu Gupta
- Department of Pathology, St John Hospital and Medical Center, Detroit, Michigan, USA.
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Hurlstone DP, Cross SS. Role of aberrant crypt foci detected using high-magnification-chromoscopic colonoscopy in human colorectal carcinogenesis. J Gastroenterol Hepatol 2005; 20:173-81. [PMID: 15683417 DOI: 10.1111/j.1440-1746.2004.03433.x] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Abstract Liaison between gastrointestinal endoscopists and histopathologists is essential to provide the highest standards of diagnostic accuracy and patient management. The histopathologist needs to be aware of the endoscopic findings when interpreting endoscopic biopsies. High-magnification-chromoscopic-colonoscopy (HMCC) is a new technology that provides the endoscopists with much greater resolution and functional staining of the gastrointestinal tract. Using HMCC, the endoscopist is now able to identify subtle changes in the colorectal luminal openings or crypts. Changes in crypt appearances now allow detection of aberrant crypt foci (ACF) in the colon, which might themselves be precancerous lesions but additionally might serve as a valid biomarker of subsequent adenoma and colorectal cancer formation. This article describes the role of the aberrant crypt focus in colorectal carcinogenesis and discusses the clinical impact of HMCC techniques as applicable to ACF.
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Affiliation(s)
- David P Hurlstone
- Gastroenterology and Liver Unit, Royal Hallamshire Hospital, Sheffield, South Yorkshire/S10, UK.
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Sekiya T, Adachi S, Kohu K, Yamada T, Higuchi O, Furukawa Y, Nakamura Y, Nakamura T, Tashiro K, Kuhara S, Ohwada S, Akiyama T. Identification of BMP and activin membrane-bound inhibitor (BAMBI), an inhibitor of transforming growth factor-beta signaling, as a target of the beta-catenin pathway in colorectal tumor cells. J Biol Chem 2003; 279:6840-6. [PMID: 14660579 DOI: 10.1074/jbc.m310876200] [Citation(s) in RCA: 114] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
The Wnt signaling pathway is activated in most human colorectal tumors. Mutational inactivation in the tumor suppressor adenomatous polyposis coli (APC), as well as activation of beta-catenin, causes the accumulation of beta-catenin, which in turn associates with the T cell factor/lymphoid enhancer factor (TCF/LEF) family of transcription factors and activates transcription of their target genes. Here we show that beta-catenin activates transcription of the BMP and activin membrane-bound inhibitor (BAMBI)/NMA gene. The expression level of BAMBI was found to be aberrantly elevated in most colorectal and hepatocellular carcinomas relative to the corresponding non-cancerous tissues. Expression of BAMBI in colorectal tumor cell lines was repressed by a dominant-negative mutant of TCF-4 or by an inhibitor of beta-catenin-TCF interaction, suggesting that beta-catenin is responsible for the aberrant expression of BAMBI in colorectal tumor cells. Furthermore, overexpression of BAMBI inhibited the response of tumor cells to transforming growth factor-beta signaling. These results suggest that beta-catenin interferes with transforming growth factor-beta-mediated growth arrest by inducing the expression of BAMBI, and this may contribute to colorectal and hepatocellular tumorigenesis.
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Affiliation(s)
- Takashi Sekiya
- Laboratory of Molecular and Genetic Information, Institute of Molecular and Cellular Biosciences, University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-0032, Japan
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Kok SH, Lee JJ, Hsu HC, Chiang CP, Kuo YS, Kuo MYP. Mutations of the adenomatous polyposis coli gene in areca quid and tobacco-associated oral squamous cell carcinomas in Taiwan. J Oral Pathol Med 2002; 31:395-401. [PMID: 12165057 DOI: 10.1034/j.1600-0714.2002.00118.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
BACKGROUND Adenomatous polyposis coli (APC) gene mutations have been demonstrated not only in colorectal tumors but also in a variety of human cancers. METHODS To elucidate the possible roles of APC gene mutations in oral squamous cell carcinomas (OSCCs), we examined 40 untreated human primary OSCCs using polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP) and DNA sequencing assays. RESULTS By screening nearly one-half of the coding region (codons 279-1673, including the MCR) of the APC gene, five missense mutations and a 1-base pair deletion were detected in five (12.5%) tumors, resulting in five amino-acid substitutions or a truncation of the APC protein. All patients with APC mutations were both areca quid chewers and tobacco smokers (P = 0.049). CONCLUSIONS These results suggest that APC mutations may also contribute to the carcinogenesis of at least some OSCCs in Taiwan, especially for the users of areca quid and tobacco.
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Affiliation(s)
- Sang-Heng Kok
- School of Dentistry, College of Medicine, National Taiwan University, Taipei, Taiwan
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Affiliation(s)
- C M Fenoglio-Preiser
- Department of Pathology and Laboratory Medicine, University of Cincinnati College of Medicine, Ohio 45267-0529, USA
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Flohr T, Dai JC, Büttner J, Popanda O, Hagmüller E, Thielmann HW. Detection of mutations in the DNA polymerase delta gene of human sporadic colorectal cancers and colon cancer cell lines. Int J Cancer 1999; 80:919-29. [PMID: 10074927 DOI: 10.1002/(sici)1097-0215(19990315)80:6<919::aid-ijc19>3.0.co;2-u] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
To test the hypothesis whether DNA polymerases acquire mutator properties during tumor development (mutator hypothesis), we examined DNA polymerase delta mRNA in 6 colon cancer cell lines (DLD-1, HCT116, SW48, HT29, SW480 and SW620) and 7 sporadic human colorectal cancers. For analysis we used amplification of cDNA by polymerase chain reaction, single-strand conformation polymorphism and sequencing techniques. In 5 of the cell lines, 9 mutations leading to changes of the amino acid sequence of DNA polymerase delta were detected. Most mutations were found in the cell lines DLD-1, HCT116 and SW48 for which defects in mismatch repair genes had been identified previously. In the majority of cases, wild type and mutated sequences were present. In 2 cell lines (HCT116 and SW48), a single-nucleotide deletion occurred at the same position. This resulted in a premature termination codon by which the DNA interaction domain of the enzyme was eliminated. Furthermore, sequence deviations were found in the tumor tissues of 4 colon cancer patients. Wild-type and altered sequences were present simultaneously. The deviations included missense mutations (2 cases) and silent mutations (2 cases). The missense mutations and one of the silent mutations were found in normal mucosa as well. In addition, the mutation clustered region of a tumor suppressor gene, often found to be defective in colon cancer, the adenomatous polyposis coli (APC) gene, was investigated in surgical specimens and cell lines. One carcinoma and 2 cell lines exhibited amino acid changes in both the DNA polymerase delta gene and in the mutation clustered region of the APC gene. Since most of the mutations detected in the DNA polymerase delta mRNA are likely to alter the structure of the protein, the enzyme is expected to be functionally impaired. In particular, copying fidelity might be decreased, thus contributing to the high mutation rate observed in colorectal cancer.
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Affiliation(s)
- T Flohr
- Division of Interaction of Carcinogens with Biologial Macromolecules, German Research Center, Heidelberg
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Sharma VA, Logan J, King DS, White R, Alber T. Sequence-based design of a peptide probe for the APC tumor suppressor protein. Curr Biol 1998; 8:823-30. [PMID: 9663391 DOI: 10.1016/s0960-9822(98)70324-0] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
BACKGROUND Proteins form specific associations, but predictive rules for protein pairing are generally unknown. Here, we describe amino-acid sequence patterns capable of mediating specific pairing of a widespread protein motif: the parallel, dimeric, alpha-helical coiled coil. The pairing rules were tested by designing a 54-residue peptide (anti-APCp1) that is predicted to dimerize preferentially with a coiled-coil sequence from the adenomatous polyposis coli (APC) tumor suppressor protein. RESULTS As judged by circular dichroism, ultracentrifugation and native gel electrophoresis, anti-APCp1 formed a specific, helical, dimeric complex with the target APC coiled coil. On western blots of APC fragments expressed in Escherichia coli, the designed peptide detected a pattern of bands identical to the pattern detected by an antibody directed against the APC coiled coil. Peptide-mediated precipitation experiments showed that anti-APCp1 bound and sequestered wild-type and mutant APC proteins in extracts of human colon cancer cell lines. In addition, binding of the designed peptide preserved native APC-beta-catenin complexes. CONCLUSIONS These biochemical experiments demonstrate that the anti-APC peptide preferentially forms a heterodimeric coiled coil with mutant and full-length APC proteins. The specificity of the designed peptide is sufficient to support several applications that commonly use antibodies. The observed specificity of anti-APCp1 validates the pairing rules used as the basis for the probe design, and it suggests that residues in the core positions of coiled coils help impart pairing selectivity.
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Affiliation(s)
- V A Sharma
- Department of Molecular and Cell Biology, University of California, Berkeley 94720-3206, USA
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Hart MJ, de los Santos R, Albert IN, Rubinfeld B, Polakis P. Downregulation of beta-catenin by human Axin and its association with the APC tumor suppressor, beta-catenin and GSK3 beta. Curr Biol 1998; 8:573-81. [PMID: 9601641 DOI: 10.1016/s0960-9822(98)70226-x] [Citation(s) in RCA: 650] [Impact Index Per Article: 25.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
BACKGROUND Inactivation of the adenomatous polyposis coli (APC) tumor suppressor protein is responsible for both inherited and sporadic forms of colon cancer. Growth control by APC may relate to its ability to downregulate beta-catenin post-translationally. In cancer, mutations in APC ablate its ability to regulate beta-catenin, and mutations in beta-catenin prevent its downregulation by wild-type APC. Moreover, signaling by the protein product of the wnt-1 proto-oncogene upregulates beta-catenin and promotes tumorigenesis in mice. In a Xenopus developmental system, Wnt-1 signaling was inhibited by Axin, the product of the murine fused gene. This suggests a possible link between Axin, the Wnt-1 signaling components beta-catenin and glycogen synthase kinase 3 beta (GSK3 beta), and APC. RESULTS Human Axin (hAxin) binds directly to beta-catenin, GSK3 beta, and APC in vitro, and the endogenous proteins are found in a complex in cells. Binding sites for Axin were mapped to a region of APC that is typically deleted due to cancer-associated mutations in the APC gene. Overexpression of hAxin strongly promoted the downregulation of wild-type beta-catenin in colon cancer cells, whereas mutant oncogenic beta-catenin was unaffected. The downregulation was increased by deletion of the APC-binding domain from Axin, suggesting that APC may function to derepress Axin activity. In addition, hAxin dramatically facilitated the phosphorylation of APC and beta-catenin by GSK3 beta in vitro. CONCLUSIONS Axin acts as a scaffold upon which APC, beta-catenin and GSK3 beta assemble to coordinate the regulation of beta-catenin signaling.
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Affiliation(s)
- M J Hart
- Onyx Pharmaceuticals, Richmond, California 94806, USA
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Nucci MR, Robinson CR, Longo P, Campbell P, Hamilton SR. Phenotypic and genotypic characteristics of aberrant crypt foci in human colorectal mucosa. Hum Pathol 1997; 28:1396-407. [PMID: 9416697 DOI: 10.1016/s0046-8177(97)90230-6] [Citation(s) in RCA: 95] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Aberrant crypt foci (ACF) in colorectal mucosa are proposed to be the earliest morphological lesion in the development of neoplasia, but their characteristics remain controversial. We therefore studied the epithelial phenotype and genotype of ACF from patients with familial adenomatous polyposis (FAP) and of sporadic ACF by evaluating glycoprotein markers associated with neoplasia (lectins Dolichus biflorus agglutinin and peanut agglutinin; monoclonal antibody CA 19-9 against sialyl Lewis-a blood group substance), expression of proliferating cell nuclear antigen, and ras proto-oncogene mutations. The utility of the markers was established by comparing adenomas and hyperplastic polyps. Most FAP ACF resembled adenomas and were found to differ from sporadic ACF in their high frequency of dysplasia, staining with Dolichus biflorus agglutinin, expression of sialyl Lewis-a, proliferation in the epithelium of upper crypts, and low frequency of ras gene mutations (P = .04 to < .0000001). By contrast, sporadic ACF and a subset of FAP ACF had phenotypic characteristics resembling hyperplastic polyps but usually had ras mutations, which were inversely related to dysplasia (P = .00009). Our findings suggest that "aberrant crypt focus" is a generic term analogous to "polyp" and requires further histopathologic, phenotypic, or genotypic classification into dysplastic and heteroplastic (hetero = other, plasia = form) types. Dysplastic ACF represent potential precursors to colorectal adenomas and adenocarcinomas, but heteroplastic ACF appear to be associated, rather than precursor, lesions.
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Affiliation(s)
- M R Nucci
- Department of Pathology and Oncology Center, The Johns Hopkins University School of Medicine and Hospital, Baltimore, MD 21205-2196, USA
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Gryfe R, Swallow C, Bapat B, Redston M, Gallinger S, Couture J. Molecular biology of colorectal cancer. Curr Probl Cancer 1997; 21:233-300. [PMID: 9438104 DOI: 10.1016/s0147-0272(97)80003-7] [Citation(s) in RCA: 163] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Colorectal cancer is a significant cause of morbidity and mortality in Western populations. This cancer develops as a result of the pathologic transformation of normal colonic epithelium to an adenomatous polyp and ultimately an invasive cancer. The multistep progression requires years and possibly decades and is accompanied by a number of recently characterized genetic alterations. Mutations in two classes of genes, tumor-suppressor genes and proto-oncogenes, are thought to impart a proliferative advantage to cells and contribute to development of the malignant phenotype. Inactivating mutations of both copies (alleles) of the adenomatous polyposis coli (APC) gene--a tumor-suppressor gene on chromosome 5q--mark one of the earliest events in colorectal carcinogenesis. Germline mutation of the APC gene and subsequent somatic mutation of the second APC allele cause the inherited familial adenomatous polyposis syndrome. This syndrome is characterized by the presence of hundreds to thousands of colonic adenomatous polyps. If these polyps are left untreated, colorectal cancer develops. Mutation leading to dysregulation of the K-ras protooncogene is also thought to be an early event in colon cancer formation. Conversely, loss of heterozygosity on the long arm of chromosome 18 (18q) occurs later in the sequence of development from adenoma to carcinoma, and this mutation may predict poor prognosis. Loss of the 18q region is thought to contribute to inactivation of the DCC tumor-suppressor gene. More recent evidence suggests that other tumor-suppressor genes--DPC4 and MADR2 of the transforming growth factor beta (TGF-beta) pathway--also may be inactivated by allelic loss on chromosome 18q. In addition, mutation of the tumor-suppressor gene p53 on chromosome 17p appears to be a late phenomenon in colorectal carcinogenesis. This mutation may allow the growing tumor with multiple genetic alterations to evade cell cycle arrest and apoptosis. Neoplastic progression is probably accompanied by additional, undiscovered genetic events, which are indicated by allelic loss on chromosomes 1q, 4p, 6p, 8p, 9q, and 22q in 25% to 50% of colorectal cancers. Recently, a third class of genes, DNA repair genes, has been implicated in tumorigenesis of colorectal cancer. Study findings suggest that DNA mismatch repair deficiency, due to germline mutation of the hMSH2, hMLH1, hPMS1, or hPMS2 genes, contributes to development of hereditary nonpolyposis colorectal cancer. The majority of tumors in patients with this disease and 10% to 15% of sporadic colon cancers display microsatellite instability, also know as the replication error positive (RER+) phenotype. This molecular marker of DNA mismatch repair deficiency may predict improved patient survival. Mismatch repair deficiency is thought to lead to mutation and inactivation of the genes for type II TGF-beta receptor and insulin-like growth-factor II receptor. Individuals from families at high risk for colorectal cancer (hereditary nonpolyposis colorectal cancer or familial adenomatous polyposis) should be offered genetic counseling, predictive molecular testing, and when indicated, endoscopic surveillance at appropriate intervals. Recent studies have examined colorectal carcinogenesis in the light of other genetic processes. Telomerase activity is present in almost all cancers, including colorectal cancer, but rarely in benign lesions such as adenomatous polyps or normal tissues. Furthermore, genetic alterations that allow transformed colorectal epithelial cells to escape cell cycle arrest or apoptosis also have been recognized. In addition, hypomethylation or hypermethylation of DNA sequences may alter gene expression without nucleic acid mutation.
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Affiliation(s)
- R Gryfe
- Department of Surgery, University of Toronto, Ontario, Canada
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Riedinger KL, Hanford MG, Farber RA. Induction of frameshift mutations in cultured mammalian cells within a transfected sequence containing a poly(dC-dA).poly(dT-dG) microsatellite. ENVIRONMENTAL AND MOLECULAR MUTAGENESIS 1996; 28:276-283. [PMID: 8908187 DOI: 10.1002/(sici)1098-2280(1996)28:3<276::aid-em12>3.0.co;2-c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
A cultured mouse cell line with an integrated copy of a plasmid that contains a short dinucleotide repeat sequence (microsatellite) has been used to determine the frequencies and types of mutation induced by two frameshift mutagens. The presence of the microsatellite, which consists of 17 repeats of a poly(dC-dA).poly(dT-dG) sequence, disrupts the reading frame of a gene coding for neomycin resistance. Revertants were selected in G418, and mutations were analyzed by PCR. ICR-170 was found to increase the reversion frequency by ten- to 15-fold at its LD50, although most of the frameshifts that it induced were single-base insertions outside the microsatellite sequence. NA-AAF brought about a more modest increase in mutation frequency, but nearly all of the revertants in the NA-AAF-treated cultures had insertions or deletions of multiples of two base pairs within the DNA segment that included the microsatellite. This system can be modified to include different short tandem repeat sequences as targets for testing of compounds that are suspected of having frameshift-inducing activities.
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Affiliation(s)
- K L Riedinger
- Department of Pathology and Laboratory Medicine, University of North Carolina at Chapel Hill 27599-7525, USA
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