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Perne C, Peters S, Cartolano M, Horpaopan S, Grimm C, Altmüller J, Sommer AK, Hillmer AM, Thiele H, Odenthal M, Möslein G, Adam R, Sivalingam S, Kirfel J, Schweiger MR, Peifer M, Spier I, Aretz S. Variant profiling of colorectal adenomas from three patients of two families with MSH3-related adenomatous polyposis. PLoS One 2021; 16:e0259185. [PMID: 34843512 PMCID: PMC8629245 DOI: 10.1371/journal.pone.0259185] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2020] [Accepted: 10/14/2021] [Indexed: 12/12/2022] Open
Abstract
The spectrum of somatic genetic variation in colorectal adenomas caused by biallelic pathogenic germline variants in the MSH3 gene, was comprehensively analysed to characterise mutational signatures and identify potential driver genes and pathways of MSH3-related tumourigenesis. Three patients from two families with MSH3-associated polyposis were included. Whole exome sequencing of nine adenomas and matched normal tissue was performed. The amount of somatic variants in the MSH3-deficient adenomas and the pattern of single nucleotide variants (SNVs) was similar to sporadic adenomas, whereas the fraction of small insertions/deletions (indels) (21-42% of all small variants) was significantly higher. Interestingly, pathogenic somatic APC variants were found in all but one adenoma. The vast majority (12/13) of these were di-, tetra-, or penta-base pair (bp) deletions. The fraction of APC indels was significantly higher than that reported in patients with familial adenomatous polyposis (FAP) (p < 0.01) or in sporadic adenomas (p < 0.0001). In MSH3-deficient adenomas, the occurrence of APC indels in a repetitive sequence context was significantly higher than in FAP patients (p < 0.01). In addition, the MSH3-deficient adenomas harboured one to five (recurrent) somatic variants in 13 established or candidate driver genes for early colorectal carcinogenesis, including ACVR2A and ARID genes. Our data suggest that MSH3-related colorectal carcinogenesis seems to follow the classical APC-driven pathway. In line with the specific function of MSH3 in the mismatch repair (MMR) system, we identified a characteristic APC mutational pattern in MSH3-deficient adenomas, and confirmed further driver genes for colorectal tumourigenesis.
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Affiliation(s)
- Claudia Perne
- Institute of Human Genetics, Medical Faculty, University of Bonn, Bonn, Germany
- Center for Hereditary Tumor Syndromes, University Hospital Bonn, Bonn, Germany
| | - Sophia Peters
- Institute of Human Genetics, Medical Faculty, University of Bonn, Bonn, Germany
| | - Maria Cartolano
- Department of Translational Genomics, Center of Integrated Oncology Cologne-Bonn, Medical Faculty, University of Cologne, Cologne, Germany
- Center for Molecular Medicine Cologne (CMMC), University of Cologne, Cologne, Germany
| | - Sukanya Horpaopan
- Department of Anatomy, Faculty of Medical Science, Naresuan University, Phitsanulok, Thailand
| | - Christina Grimm
- Institute for Translational Epigenetics, Medical Faculty and University Clinic Cologne, University of Cologne, Cologne, Germany
| | - Janine Altmüller
- Center for Molecular Medicine Cologne (CMMC), University of Cologne, Cologne, Germany
- Cologne Center for Genomics (CCG), Faculty of Medicine, University of Cologne, University Hospital Cologne, Cologne, Germany
- Berlin Institute of Health at Charité, Core Facility Genomics, Berlin, Germany
- Max Delbrück Center for Molecular Medicine in the Helmholtz Association, Berlin, Germany
| | - Anna K. Sommer
- Institute of Human Genetics, Medical Faculty, University of Bonn, Bonn, Germany
| | - Axel M. Hillmer
- Institute of Pathology, Faculty of Medicine and University Hospital Cologne, University of Cologne, Cologne, Germany
| | - Holger Thiele
- Cologne Center for Genomics (CCG), Faculty of Medicine, University of Cologne, University Hospital Cologne, Cologne, Germany
| | - Margarete Odenthal
- Center for Molecular Medicine Cologne (CMMC), University of Cologne, Cologne, Germany
- Institute of Pathology, Faculty of Medicine and University Hospital Cologne, University of Cologne, Cologne, Germany
| | - Gabriela Möslein
- Zentrum für Hereditäre Tumore, BETHESDA Khs. Duisburg, Duisburg, Germany
| | - Ronja Adam
- Cancer Center Amsterdam, Amsterdam University Medical Centers, Amsterdam, The Netherlands
| | - Sugirthan Sivalingam
- Core Unit for Bioinformatics Data Analysis, Medical Faculty, University of Bonn, Bonn, Germany
- Institute for Genomic Statistics and Bioinformatics, Medical Faculty, University of Bonn, Bonn, Germany
- Institute for Medical Biometry, Informatics and Epidemiology, Medical Faculty, University of Bonn, Bonn, Germany
| | - Jutta Kirfel
- Institute of Pathology, University of Lübeck, Lübeck, Germany
| | - Michal R. Schweiger
- Center for Molecular Medicine Cologne (CMMC), University of Cologne, Cologne, Germany
- Institute for Translational Epigenetics, Medical Faculty and University Clinic Cologne, University of Cologne, Cologne, Germany
| | - Martin Peifer
- Department of Translational Genomics, Center of Integrated Oncology Cologne-Bonn, Medical Faculty, University of Cologne, Cologne, Germany
| | - Isabel Spier
- Institute of Human Genetics, Medical Faculty, University of Bonn, Bonn, Germany
- Center for Hereditary Tumor Syndromes, University Hospital Bonn, Bonn, Germany
| | - Stefan Aretz
- Institute of Human Genetics, Medical Faculty, University of Bonn, Bonn, Germany
- Center for Hereditary Tumor Syndromes, University Hospital Bonn, Bonn, Germany
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Yuza K, Nagahashi M, Ichikawa H, Hanyu T, Nakajima M, Shimada Y, Ishikawa T, Sakata J, Takeuchi S, Okuda S, Matsuda Y, Abe M, Sakimura K, Takabe K, Wakai T. Activin a Receptor Type 2A Mutation Affects the Tumor Biology of Microsatellite Instability-High Gastric Cancer. J Gastrointest Surg 2021; 25:2231-2241. [PMID: 33420656 PMCID: PMC8728635 DOI: 10.1007/s11605-020-04889-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/04/2020] [Accepted: 11/22/2020] [Indexed: 01/31/2023]
Abstract
BACKGROUND Activin A receptor type 2A (ACVR2A) is one of the most frequently mutated genes in microsatellite instability-high (MSI-H) gastric cancer. However, the clinical relevance of the ACVR2A mutation in MSI-H gastric cancer patients remains unclear. The aims of this study were to explore the effect of ACVR2A mutation on the tumor behavior and to identify the clinicopathological characteristics of gastric cancer patients with ACVR2A mutations. METHODS An in vitro study was performed to investigate the biological role of ACVR2A via CRISPR/Cas9-mediated ACVR2A knockout MKN74 human gastric cancer cells. One hundred twenty-four patients with gastric cancer were retrospectively analyzed, and relations between MSI status, ACVR2A mutations, and clinicopathological factors were evaluated. RESULTS ACVR2A knockout cells showed less aggressive tumor biology than mock-transfected cells, displaying reduced proliferation, migration, and invasion (P < 0.05). MSI mutations were found in 10% (13/124) of gastric cancer patients, and ACVR2A mutations were found in 8.1% (10/124) of patients. All ACVR2A mutations were accompanied by MSI. The 5-year overall survival rates of ACVR2A wild-type patients and ACVR2A-mutated patients were 57% and 90%, respectively (P = 0.048). Multivariate analysis revealed that older age (P = 0.015), distant metastasis (P < 0.001), and ACVR2A wild-type status (P = 0.040) were independent prognostic factors for overall survival. CONCLUSIONS Our study demonstrated that gastric cancer patients with ACVR2A mutation have a significantly better prognosis than those without. Dysfunction of ACVR2A in MKN74 human gastric cancer cells caused less aggressive tumor biology, indicating the importance of ACVR2A in the progression of MSI-H tumors.
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Affiliation(s)
- Kizuki Yuza
- Division of Digestive and General Surgery, Niigata University Graduate School of Medical and Dental Sciences, 1-757 Asahimachi-dori, Chuo-ku, Niigata City, Niigata 951-8510, Japan
| | - Masayuki Nagahashi
- Division of Digestive and General Surgery, Niigata University Graduate School of Medical and Dental Sciences, 1-757 Asahimachi-dori, Chuo-ku, Niigata City, Niigata 951-8510, Japan
| | - Hiroshi Ichikawa
- Division of Digestive and General Surgery, Niigata University Graduate School of Medical and Dental Sciences, 1-757 Asahimachi-dori, Chuo-ku, Niigata City, Niigata 951-8510, Japan
| | - Takaaki Hanyu
- Division of Digestive and General Surgery, Niigata University Graduate School of Medical and Dental Sciences, 1-757 Asahimachi-dori, Chuo-ku, Niigata City, Niigata 951-8510, Japan
| | - Masato Nakajima
- Division of Digestive and General Surgery, Niigata University Graduate School of Medical and Dental Sciences, 1-757 Asahimachi-dori, Chuo-ku, Niigata City, Niigata 951-8510, Japan
| | - Yoshifumi Shimada
- Division of Digestive and General Surgery, Niigata University Graduate School of Medical and Dental Sciences, 1-757 Asahimachi-dori, Chuo-ku, Niigata City, Niigata 951-8510, Japan
| | - Takashi Ishikawa
- Division of Digestive and General Surgery, Niigata University Graduate School of Medical and Dental Sciences, 1-757 Asahimachi-dori, Chuo-ku, Niigata City, Niigata 951-8510, Japan
| | - Jun Sakata
- Division of Digestive and General Surgery, Niigata University Graduate School of Medical and Dental Sciences, 1-757 Asahimachi-dori, Chuo-ku, Niigata City, Niigata 951-8510, Japan
| | - Shiho Takeuchi
- Division of Cancer Genome Informatics, Niigata University Graduate School of Medical and Dental Sciences, 1-757 Asahimachi-dori, Chuo-ku, Niigata City, Niigata 951-8510, Japan,Division of Bioinformatics, Niigata University Graduate School of Medical and Dental Sciences, 1-757 Asahimachi-dori, Chuo-ku, Niigata City, Niigata 951-8510, Japan
| | - Shujiro Okuda
- Division of Bioinformatics, Niigata University Graduate School of Medical and Dental Sciences, 1-757 Asahimachi-dori, Chuo-ku, Niigata City, Niigata 951-8510, Japan
| | - Yasunobu Matsuda
- Department of Medical Technology, Niigata University Graduate School of Health Sciences, 2-746 Asahimachi-dori, Chuo-Ku, Niigata City, Niigata 951-8518, Japan
| | - Manabu Abe
- Department of Animal Model Development, Brain Research Institute, Niigata University, 1-757 Asahimachi-dori, Chuo-ku, Niigata City, Niigata 951-8585, Japan
| | - Kenji Sakimura
- Department of Animal Model Development, Brain Research Institute, Niigata University, 1-757 Asahimachi-dori, Chuo-ku, Niigata City, Niigata 951-8585, Japan
| | - Kazuaki Takabe
- Division of Digestive and General Surgery, Niigata University Graduate School of Medical and Dental Sciences, 1-757 Asahimachi-dori, Chuo-ku, Niigata City, Niigata 951-8510, Japan,Breast Surgery, Department of Surgical Oncology, Roswell Park Cancer Institute, Buffalo, NY 14263, USA,Department of Surgery, University at Buffalo Jacobs School of Medicine and Biomedical Sciences, The State University of New York, Buffalo, NY 14263, USA
| | - Toshifumi Wakai
- Division of Digestive and General Surgery, Niigata University Graduate School of Medical and Dental Sciences, 1-757 Asahimachi-dori, Chuo-ku, Niigata City, Niigata 951-8510, Japan
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Raeker MO, Carethers JM. Immunological Features with DNA Microsatellite Alterations in Patients with Colorectal Cancer. JOURNAL OF CANCER IMMUNOLOGY 2020; 2:116-127. [PMID: 33000102 DOI: 10.33696/cancerimmunol.2.024] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Competent human DNA mismatch repair (MMR) corrects DNA polymerase mistakes made during cell replication to maintain complete DNA fidelity in daughter cells; faulty DNA MMR occurs in the setting of inflammation and neoplasia, creating base substitutions (e.g. point mutations) and frameshift mutations at DNA microsatellite sequences in progeny cells. Frameshift mutations at DNA microsatellite sequences are a detected biomarker termed microsatellite instability (MSI) for human disease, as this marker can prognosticate and determine therapeutic approaches for patients with cancer. There are two types of MSI: MSI-High (MSI-H), defined by frameshifts at mono- and di-nucleotide microsatellite sequences, and elevated microsatellite alterations at selected tetranucleotide repeats or EMAST, defined by frameshifts in di- and tetranucleotide microsatellite sequences but not mononucleotide sequences. Patients with colorectal cancers (CRCs) manifesting MSI-H demonstrate improved survival over patients without an MSI-H tumor, driven by the generation of immunogenic neoantigens caused by novel truncated proteins from genes whose sequences contain coding microsatellites; these patients' tumors contain hundreds of somatic mutations, and show responsiveness to treatment with immune checkpoint inhibitors. Patients with CRCs manifesting EMAST demonstrate poor survival over patients without an EMAST tumor, and may be driven by a more dominant defect in double strand break repair attributed to the MMR protein MSH3 over its frameshift correcting function; these patients' tumors often have a component of inflammation (and are also termed inflammation-associated microsatellite alterations) and show less somatic mutations and lack coding mononucleotide frameshift mutations that seem to generate the neoantigens seen in the majority of MSI-H tumors. Overall, both types of MSI are biomarkers that can prognosticate patients with CRC, can be tested for simultaneously in marker panels, and informs the approach to specific therapy including immunotherapy for their cancers.
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Affiliation(s)
- Maide O Raeker
- Division of Gastroenterology and Hepatology, Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan
| | - John M Carethers
- Division of Gastroenterology and Hepatology, Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan.,Department of Human Genetics and Rogel Cancer Center, University of Michigan, Ann Arbor, Michigan
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4
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Wodziński D, Wosiak A, Pietrzak J, Świechowski R, Jeleń A, Balcerczak E. Does the expression of the ACVR2A gene affect the development of colorectal cancer? Genet Mol Biol 2019; 42:32-39. [PMID: 30856244 PMCID: PMC6428132 DOI: 10.1590/1678-4685-gmb-2017-0332] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2017] [Accepted: 06/21/2018] [Indexed: 01/19/2023] Open
Abstract
Colorectal cancer has become a serious problem, especially in highly developed
countries. As reported by the World Health Organization, the number of colon
cancer cases in the world in 2012 amounted to 1.36 million. It is the second
most common cancer in females (614,000 cases, 9.2% of the total) and the third
in males (746,000 cases, 10.0% of the total) worldwide. It is believed that TGFβ
pathway elements are involved in the pathogenesis of colorectal cancer. This
study assessed one of these elements, the ACVR2A gene.
Qualitative and quantitative analyses of the ACVR2A gene in 84
patients with colorectal cancer was performed. There was no statistically
significant association between ACVR2A gene expression and age,
gender, histological type, grading of tumor, vascular invasion, and presence of
lymphocytes in tumor tissue. No association was observed between the
ACVR2A gene expression level and the presence of metastases
in regional lymph nodes and distant metastases. In this study, larger tumors (T3
and T4) were characterized by higher ACVR2A expression compared
to smaller tumors (T1 and T2). This may indicate an association between
ACVR2A expression and the severity of pathological changes
in the tumor growth process.
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Affiliation(s)
- Damian Wodziński
- Laboratory of Molecular Diagnostics and Pharmacogenomics, Department of Pharmaceutical Biochemistry and Molecular Diagnostics, Interfaculty Cathedral of Laboratory and Molecular Diagnostics, Medical University of Lodz, Lodz, Poland
| | - Agnieszka Wosiak
- Laboratory of Molecular Diagnostics and Pharmacogenomics, Department of Pharmaceutical Biochemistry and Molecular Diagnostics, Interfaculty Cathedral of Laboratory and Molecular Diagnostics, Medical University of Lodz, Lodz, Poland
| | - Jacek Pietrzak
- Laboratory of Molecular Diagnostics and Pharmacogenomics, Department of Pharmaceutical Biochemistry and Molecular Diagnostics, Interfaculty Cathedral of Laboratory and Molecular Diagnostics, Medical University of Lodz, Lodz, Poland
| | - Rafał Świechowski
- Laboratory of Molecular Diagnostics and Pharmacogenomics, Department of Pharmaceutical Biochemistry and Molecular Diagnostics, Interfaculty Cathedral of Laboratory and Molecular Diagnostics, Medical University of Lodz, Lodz, Poland
| | - Agnieszka Jeleń
- Laboratory of Molecular Diagnostics and Pharmacogenomics, Department of Pharmaceutical Biochemistry and Molecular Diagnostics, Interfaculty Cathedral of Laboratory and Molecular Diagnostics, Medical University of Lodz, Lodz, Poland
| | - Ewa Balcerczak
- Laboratory of Molecular Diagnostics and Pharmacogenomics, Department of Pharmaceutical Biochemistry and Molecular Diagnostics, Interfaculty Cathedral of Laboratory and Molecular Diagnostics, Medical University of Lodz, Lodz, Poland
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5
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Mañas A, Chen W, Nelson A, Yao Q, Xiang J. BaxΔ2 sensitizes colorectal cancer cells to proteasome inhibitor-induced cell death. Biochem Biophys Res Commun 2018; 496:18-24. [PMID: 29291406 PMCID: PMC6022363 DOI: 10.1016/j.bbrc.2017.12.156] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2017] [Accepted: 12/26/2017] [Indexed: 12/23/2022]
Abstract
Proteasome inhibitors, such as bortezomib and carfilzomib, are FDA approved for the treatment of hemopoietic cancers, but recent studies have shown their great potential for treatment of solid tumors. BaxΔ2, a unique proapoptotic Bax isoform, promotes non-mitochondrial cell death and sensitizes cancer cells to chemotherapy. However, endogenous BaxΔ2 proteins are unstable and susceptible to proteasomal degradation. Here, we screened a panel of proteasome inhibitors in colorectal cancer cells with different Bax statuses. We found that all proteasome inhibitors tested were able to block BaxΔ2 degradation without affecting the level of Baxα or Bcl-2 proteins. Among the inhibitors tested, only bortezomib and carfilzomib were able to induce differential cell death corresponding to the distinct Bax statuses. BaxΔ2-positive cells had a significantly higher level of cell death at low nanomolar concentrations than Baxα-positive or Bax-negative cells. Furthermore, bortezomib-induced cell death in BaxΔ2-positive cells was predominantly dependent on the caspase 8/3 pathway, consistent with our previous studies. These results imply that BaxΔ2 can selectively sensitize cancer cells to proteasome inhibitors, enhancing their potential to treat colon cancer and other solid tumors.
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Affiliation(s)
- Adriana Mañas
- Department of Biology, Illinois Institute of Technology, Chicago, IL 60616, USA
| | - Wenjing Chen
- Department of Biology, Illinois Institute of Technology, Chicago, IL 60616, USA
| | - Adam Nelson
- Department of Biology, Illinois Institute of Technology, Chicago, IL 60616, USA
| | - Qi Yao
- Department of Biology, Illinois Institute of Technology, Chicago, IL 60616, USA
| | - Jialing Xiang
- Department of Biology, Illinois Institute of Technology, Chicago, IL 60616, USA.
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6
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Udagawa C, Sasaki Y, Suemizu H, Ohnishi Y, Ohnishi H, Tokino T, Zembutsu H. Targeted sequencing reveals genetic variants associated with sensitivity of 79 human cancer xenografts to anticancer drugs. Exp Ther Med 2017; 15:1339-1359. [PMID: 29434720 PMCID: PMC5774388 DOI: 10.3892/etm.2017.5533] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2017] [Accepted: 04/28/2017] [Indexed: 02/07/2023] Open
Abstract
Although there has been progress moving from a 'one-size-fits-all' cytotoxic approach to personalized molecular medicine, the majority of patients with cancer receive chemotherapy using cytotoxic anticancer drugs. The sequencing analysis of 409 genes associated with cancer was conducted in the present study using 59 DNA sequences extracted from human cancer xenografts implanted into nude mice, of which sensitivity to 9 cytotoxic anticancer drugs [5-fluorouracil, nimustine, adriamycin, cyclophosphamide, cisplatin, mitomycin C (MMC), methotrexate, vincristine (VCR), and vinblastine] was examined. The present study investigated the association between the sensitivities of the xenografts to the 9 anticancer drugs and the frequency of single nucleotide variants (SNV). The correlation between the expression level of the genes and sensitivities to the 9 drugs in the above xenografts was also estimated. In the screening study using 59 xenografts, 3 SNVs (rs1805321, rs62456182 in PMS1 Homolog 2, Mismatch Repair System Component and rs13382825 in LDL Receptor Related Protein 1B), were associated with sensitivity to VCR and MMC, respectively (P<0.001). A replication study of 596 SNVs was subsequently performed, which indicated P<0.05 in the screening study using independent samples of 20 xenografts. A combined result of the screening and replication studies indicated that 35 SNVs were potentially associated with sensitivities to one or more of the nine anticancer drugs (Pcombined=0.0011-0.035). Of the 35 SNVs, rs16903989 and rs201432181 in Leukemia Inhibitory Factor Receptor α and Adhesion G Protein-Coupled Receptor A2 were commonly associated with sensitivity to 2 or 4 anticancer drugs, respectively. These findings provide novel insights which may benefit the development of personalized anticancer therapy for patients with cancer in the future.
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Affiliation(s)
- Chihiro Udagawa
- Liquid Biopsy Development Group, Project for Development of Liquid Biopsy Diagnosis, Cancer Precision Medicine Center, Japanese Foundation for Cancer Research, Tokyo 135-8550, Japan.,Division of Genetics, National Cancer Center Research Institute, Tokyo 104-0045, Japan
| | - Yasushi Sasaki
- Department of Medical Genome Science, Research Institute for Frontier Medicine, Sapporo Medical University, School of Medicine, Hokkaido 060-8556, Japan
| | - Hiroshi Suemizu
- Laboratory Animal Research Department, Central Institute for Experimental Animals, Kawasaki, 210-0821, Japan
| | - Yasuyuki Ohnishi
- Laboratory Animal Research Department, Central Institute for Experimental Animals, Kawasaki, 210-0821, Japan
| | - Hiroshi Ohnishi
- Liquid Biopsy Development Group, Project for Development of Liquid Biopsy Diagnosis, Cancer Precision Medicine Center, Japanese Foundation for Cancer Research, Tokyo 135-8550, Japan
| | - Takashi Tokino
- Department of Medical Genome Science, Research Institute for Frontier Medicine, Sapporo Medical University, School of Medicine, Hokkaido 060-8556, Japan
| | - Hitoshi Zembutsu
- Liquid Biopsy Development Group, Project for Development of Liquid Biopsy Diagnosis, Cancer Precision Medicine Center, Japanese Foundation for Cancer Research, Tokyo 135-8550, Japan.,Division of Genetics, National Cancer Center Research Institute, Tokyo 104-0045, Japan
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7
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Jung B, Staudacher JJ, Beauchamp D. Transforming Growth Factor β Superfamily Signaling in Development of Colorectal Cancer. Gastroenterology 2017; 152:36-52. [PMID: 27773809 PMCID: PMC5550896 DOI: 10.1053/j.gastro.2016.10.015] [Citation(s) in RCA: 170] [Impact Index Per Article: 24.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/25/2016] [Revised: 09/29/2016] [Accepted: 10/11/2016] [Indexed: 02/07/2023]
Abstract
Transforming growth factor (TGF)-β cytokines signal via a complex network of pathways to regulate proliferation, differentiation, adhesion, migration, and other functions in many cell types. A high percentage of colorectal tumors contain mutations that disrupt TGF-β family member signaling. We review how TGF-β family member signaling is altered during development of colorectal cancer, models of study, interaction of pathways, and potential therapeutic strategies.
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Affiliation(s)
- Barbara Jung
- University of Illinois at Chicago, Chicago, Illinois.
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8
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Bauer J, Ozden O, Akagi N, Carroll T, Principe DR, Staudacher JJ, Spehlmann ME, Eckmann L, Grippo PJ, Jung B. Activin and TGFβ use diverging mitogenic signaling in advanced colon cancer. Mol Cancer 2015; 14:182. [PMID: 26497569 PMCID: PMC4619565 DOI: 10.1186/s12943-015-0456-4] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2015] [Accepted: 10/16/2015] [Indexed: 02/08/2023] Open
Abstract
Background Understanding cell signaling pathways that contribute to metastatic colon cancer is critical to risk stratification in the era of personalized therapeutics. Here, we dissect the unique involvement of mitogenic pathways in a TGFβ or activin-induced metastatic phenotype of colon cancer. Method Mitogenic signaling/growth factor receptor status and p21 localization were correlated in primary colon cancers and intestinal tumors from either AOM/DSS treated ACVR2A (activin receptor 2) −/− or wild type mice. Colon cancer cell lines (+/− SMAD4) were interrogated for ligand-induced PI3K and MEK/ERK pathway activation and downstream protein/phospho-isoform expression/association after knockdown and pharmacologic inhibition of pathway members. EMT was assessed using epithelial/mesenchymal markers and migration assays. Results In primary colon cancers, loss of nuclear p21 correlated with upstream activation of activin/PI3K while nuclear p21 expression was associated with TGFβ/MEK/ERK pathway activation. Activin, but not TGFβ, led to PI3K activation via interaction of ACVR1B and p85 independent of SMAD4, resulting in p21 downregulation. In contrast, TGFβ increased p21 via MEK/ERK pathway through a SMAD4-dependent mechanism. While activin induced EMT via PI3K, TGFβ induced EMT via MEK/ERK activation. In vivo, loss of ACVR2A resulted in loss of pAkt, consistent with activin-dependent PI3K signaling. Conclusion Although activin and TGFβ share growth suppressive SMAD signaling in colon cancer, they diverge in their SMAD4-independent pro-migratory signaling utilizing distinct mitogenic signaling pathways that affect EMT. p21 localization in colon cancer may determine a dominant activin versus TGFβ ligand signaling phenotype warranting further validation as a therapeutic biomarker prior to targeting TGFβ family receptors. Electronic supplementary material The online version of this article (doi:10.1186/s12943-015-0456-4) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Jessica Bauer
- Department of Medicine, Division of Gastroenterology and Hepatology, University of Illinois at Chicago, 840 South Wood Street, 738A CSB, Chicago, IL, 60612, USA
| | - Ozkan Ozden
- Department of Medicine, Division of Gastroenterology and Hepatology, University of Illinois at Chicago, 840 South Wood Street, 738A CSB, Chicago, IL, 60612, USA
| | - Naomi Akagi
- Department of Medicine, Division of Gastroenterology and Hepatology, University of Illinois at Chicago, 840 South Wood Street, 738A CSB, Chicago, IL, 60612, USA
| | - Timothy Carroll
- Department of Medicine, Division of Gastroenterology and Hepatology, University of Illinois at Chicago, 840 South Wood Street, 738A CSB, Chicago, IL, 60612, USA
| | - Daniel R Principe
- Department of Medicine, Division of Gastroenterology and Hepatology, University of Illinois at Chicago, 840 South Wood Street, 738A CSB, Chicago, IL, 60612, USA
| | - Jonas J Staudacher
- Department of Medicine, Division of Gastroenterology and Hepatology, University of Illinois at Chicago, 840 South Wood Street, 738A CSB, Chicago, IL, 60612, USA
| | - Martina E Spehlmann
- Department of Internal Medicine III, Cardiology and Angiology, University Hospital Schleswig-Holstein, Kiel, Germany
| | - Lars Eckmann
- Department of Medicine, University of California, San Diego, CA, USA
| | - Paul J Grippo
- Department of Medicine, Division of Gastroenterology and Hepatology, University of Illinois at Chicago, 840 South Wood Street, 738A CSB, Chicago, IL, 60612, USA
| | - Barbara Jung
- Department of Medicine, Division of Gastroenterology and Hepatology, University of Illinois at Chicago, 840 South Wood Street, 738A CSB, Chicago, IL, 60612, USA.
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9
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Bathe OF, Farshidfar F. From genotype to functional phenotype: unraveling the metabolomic features of colorectal cancer. Genes (Basel) 2014; 5:536-60. [PMID: 25055199 PMCID: PMC4198916 DOI: 10.3390/genes5030536] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2014] [Revised: 05/27/2014] [Accepted: 06/27/2014] [Indexed: 12/12/2022] Open
Abstract
Much effort in recent years has been expended in defining the genomic and epigenetic alterations that characterize colorectal adenocarcinoma and its subtypes. However, little is known about the functional ramifications related to various subtypes. Metabolomics, the study of small molecule intermediates in disease, provides a snapshot of the functional phenotype of colorectal cancer. Data, thus far, have characterized some of the metabolic perturbations that accompany colorectal cancer. However, further studies will be required to identify biologically meaningful metabolic subsets, including those corresponding to specific genetic aberrations. Moreover, further studies are necessary to distinguish changes due to tumor and the host response to tumor.
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Affiliation(s)
- Oliver F Bathe
- Department of Surgery, Tom Baker Cancer Center, University of Calgary, 1331 29th St NW, Calgary, AB T2N 4N2, Canada.
| | - Farshad Farshidfar
- Department of Surgery, Tom Baker Cancer Center, University of Calgary, 1331 29th St NW, Calgary, AB T2N 4N2, Canada.
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Kim JH, Kang GH. Molecular and prognostic heterogeneity of microsatellite-unstable colorectal cancer. World J Gastroenterol 2014; 20:4230-4243. [PMID: 24764661 PMCID: PMC3989959 DOI: 10.3748/wjg.v20.i15.4230] [Citation(s) in RCA: 72] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/25/2013] [Revised: 01/30/2014] [Accepted: 02/20/2014] [Indexed: 02/06/2023] Open
Abstract
Colorectal cancers (CRCs) with a high level of microsatellite instability (MSI-H) are clinicopathologically distinct tumors characterized by predominance in females, proximal colonic localization, poor differentiation, mucinous histology, tumor-infiltrating lymphocytes, a Crohn’s-like lymphoid reaction and a favorable prognosis. In terms of their molecular features, MSI-H CRCs are heterogeneous tumors associated with various genetic and epigenetic alterations, including DNA mismatch repair deficiency, target microsatellite mutations, BRAF mutations, a CpG island methylator phenotype-high (CIMP-H) status, and a low level of genomic hypomethylation. The molecular heterogeneity of MSI-H CRCs also depends on ethnic differences; for example, in Eastern Asian countries, relatively low frequencies of CIMP-H and BRAF mutations have been observed in MSI-H CRCs compared to Western countries. Although the prognostic features of MSI-H CRCs include a favorable survival of patients and low benefit of adjuvant chemotherapy, there may be prognostic differences based on the molecular heterogeneity of MSI-H CRCs. Here, we have reviewed and discussed the molecular and prognostic features of MSI-H CRCs, as well as several putative prognostic or predictive molecular markers, including HSP110 expression, beta2-microglobulin mutations, myosin 1a expression, CDX2/CK20 expression, SMAD4 expression, CIMP status and LINE-1 methylation levels.
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Haferkamp B, Zhang H, Kissinger S, Wang X, Lin Y, Schultz M, Xiang J. BaxΔ2 Family Alternative Splicing Salvages Bax Microsatellite-Frameshift Mutations. Genes Cancer 2014; 4:501-12. [PMID: 24386510 DOI: 10.1177/1947601913515906] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2013] [Accepted: 11/14/2013] [Indexed: 12/15/2022] Open
Abstract
Mutation or aberrant splicing can interrupt gene expression. Tumor suppressor Bax is one of the susceptible genes prone to microsatellite frameshifting mutations in coding regions. As a result, tumors exhibiting microsatellite instability (MSI) often present a "Bax-negative" phenotype. We previously reported that some Bax-negative cells in fact contain a functional Bax isoform (BaxΔ2), generated when unique alternative splicing "salvages" the shifted reading frame introduced by a microsatellite mutation. Here we compared Bax alternative splicing profiles in a range of cell lines and primary tumors with and without Bax microsatellite mutations. We found that MSI tumors exhibit a high Bax alternative splicing frequency, especially in exon 2, and produce a family of alternatively spliced isoforms that retain many important Bax functional domains. Surprisingly, these BaxΔ2 family isoforms can rescue Bax from all common microsatellite frameshift mutations. Production of BaxΔ2 requires specific cis mutations, while trans components are not cell-type specific. Furthermore, all BaxΔ2 family isoforms are more potent cell death inducers than the parental Bax without directly targeting mitochondria. These results indicate that the BaxΔ2 family can potentially salvage Bax tumor suppressor expression otherwise lost to mutation.
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Affiliation(s)
- Bonnie Haferkamp
- Department of Biological and Chemical Sciences, Illinois Institute of Technology, Chicago, IL, USA
| | - Honghong Zhang
- Department of Biological and Chemical Sciences, Illinois Institute of Technology, Chicago, IL, USA
| | - Samuel Kissinger
- Department of Biological and Chemical Sciences, Illinois Institute of Technology, Chicago, IL, USA
| | - Xin Wang
- Department of Biological and Chemical Sciences, Illinois Institute of Technology, Chicago, IL, USA
| | - Yuting Lin
- Department of Biological and Chemical Sciences, Illinois Institute of Technology, Chicago, IL, USA
| | - Megan Schultz
- Department of Biological and Chemical Sciences, Illinois Institute of Technology, Chicago, IL, USA
| | - Jialing Xiang
- Department of Biological and Chemical Sciences, Illinois Institute of Technology, Chicago, IL, USA
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12
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Haferkamp B, Zhang H, Lin Y, Yeap X, Bunce A, Sharpe J, Xiang J. BaxΔ2 is a novel bax isoform unique to microsatellite unstable tumors. J Biol Chem 2012; 287:34722-9. [PMID: 22910913 PMCID: PMC3464575 DOI: 10.1074/jbc.m112.374785] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
The pro-death Bcl-2 family protein and tumor suppressor Bax is frequently mutated in tumors with microsatellite instability (MSI). The mutation often results in a "Bax negative" phenotype and therefore is generally thought to be beneficial to the development of the tumor. Here, we report the identification of a novel Bax isoform, BaxΔ2, which is unique to microsatellite unstable tumors. BaxΔ2 is generated by a unique combination of a microsatellite deletion in Bax exon 3 and alternative splicing of Bax exon 2. Consistently, BaxΔ2 is only detected in MSI cell lines and primary tumors. BaxΔ2 is a potent cell death inducer but does not directly target mitochondria. In addition, BaxΔ2 sensitizes certain MSI tumor cells to a subset of chemotherapeutic agents, such as adriamycin. Thus, our data provide evidence that mutation and alternative splicing of tumor suppressors such as Bax are not always beneficial to tumor development but can be detrimental instead.
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Affiliation(s)
- Bonnie Haferkamp
- From the Illinois Institute of Technology, Chicago, Illinois 60616 and
| | - Honghong Zhang
- From the Illinois Institute of Technology, Chicago, Illinois 60616 and
| | - Yuting Lin
- From the Illinois Institute of Technology, Chicago, Illinois 60616 and
| | - Xinyi Yeap
- From the Illinois Institute of Technology, Chicago, Illinois 60616 and
| | - Alex Bunce
- From the Illinois Institute of Technology, Chicago, Illinois 60616 and
| | | | - Jialing Xiang
- From the Illinois Institute of Technology, Chicago, Illinois 60616 and
- To whom correspondence should be addressed: Dept. of Biological and Chemical Sciences, Illinois Institute of Technology, 3101 South Dearborn St., Chicago, IL 60616. Tel.: 312-567-3491; Fax: 312-567-3494; E-mail:
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13
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Bauer J, Sporn JC, Cabral J, Gomez J, Jung B. Effects of activin and TGFβ on p21 in colon cancer. PLoS One 2012; 7:e39381. [PMID: 22761777 PMCID: PMC3383701 DOI: 10.1371/journal.pone.0039381] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2012] [Accepted: 05/21/2012] [Indexed: 12/21/2022] Open
Abstract
Activin and TGFβ share SMAD signaling and colon cancers can inactivate either pathway alone or simultaneously. The differential effects of activin and TGFβ signaling in colon cancer have not been previously dissected. A key downstream target of TGFβ signaling is the cdk2 inhibitor p21 (p21cip1/waf1). Here, we evaluate activin-specific effects on p21 regulation and resulting functions. We find that TGFβ is a more potent inducer of growth suppression, while activin is a more potent inducer of apoptosis. Further, growth suppression and apoptosis by both ligands are dependent on SMAD4. However, activin downregulates p21 protein in a SMAD4-independent fashion in conjunction with increased ubiquitination and proteasomal degradation to enhance migration, while TGFβ upregulates p21 in a SMAD4-dependent fashion to affect growth arrest. Activin-induced growth suppression and cell death are dependent on p21, while activin-induced migration is counteracted by p21. Further, primary colon cancers show differential p21 expression consistent with their ACVR2/TGFBR2 receptor status. In summary, we report p21 as a differentially affected activin/TGFβ target and mediator of ligand-specific functions in colon cancer, which may be exploited for future risk stratification and therapeutic intervention.
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Affiliation(s)
- Jessica Bauer
- Department of Medicine, Northwestern University Feinberg School of Medicine, Chicago, Illinois, United States of America
| | - Judith C. Sporn
- Department of Medicine, Northwestern University Feinberg School of Medicine, Chicago, Illinois, United States of America
| | - Jennifer Cabral
- Department of Medicine, University of California San Diego, La Jolla, California, United States of America
| | - Jessica Gomez
- Department of Medicine, University of California San Diego, La Jolla, California, United States of America
| | - Barbara Jung
- Department of Medicine, Northwestern University Feinberg School of Medicine, Chicago, Illinois, United States of America
- * E-mail:
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Legolvan MP, Taliano RJ, Resnick MB. Application of molecular techniques in the diagnosis, prognosis and management of patients with colorectal cancer: a practical approach. Hum Pathol 2012; 43:1157-68. [PMID: 22658275 DOI: 10.1016/j.humpath.2012.03.003] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/09/2011] [Revised: 02/29/2012] [Accepted: 03/02/2012] [Indexed: 12/13/2022]
Abstract
There has been an increasing role for molecular diagnostics in the diagnosis and management of cancer, and colorectal carcinoma is no exception. Recent molecular advances have elucidated 3 broad molecular subtypes of colorectal cancer, including chromosomal instability, microsatellite instability, and cytosine-phosphoguanine island methylator phenotype, which will be discussed. Also, the common syndromes associated with colorectal carcinoma will be reviewed with a focus on the differentiation between Lynch syndrome and microsatellite unstable tumors. Molecular biomarkers for predictive and prognostic markers are also becoming widely used, and due to the clinical use of monoclonal antibodies to the epidermal growth factor receptor, an emphasis is placed on that pathway.
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Affiliation(s)
- Mark P Legolvan
- Department of Pathology, Rhode Island Hospital, and the Alpert Medical School of Brown University, Providence, RI 02908, USA
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15
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Flanking nucleotide specificity for DNA mismatch repair-deficient frameshifts within activin receptor 2 (ACVR2). Mutat Res 2011; 729:73-80. [PMID: 22001236 DOI: 10.1016/j.mrfmmm.2011.09.009] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2011] [Accepted: 09/27/2011] [Indexed: 11/23/2022]
Abstract
We previously demonstrated that exonic selectivity for frameshift mutation (exon 10 over exon 3) of ACVR2 in mismatch repair (MMR)-deficient cells is partially determined by 6 nucleotides flanking 5' and 3' of each microsatellite. Substitution of flanking nucleotides surrounding the exon 10 microsatellite with those surrounding the exon 3 microsatellite greatly diminished heteroduplex (A(7)/T(8)) and full (A(7)/T(7)) mutation, while substitution of flanking nucleotides from exon 3 with those from exon 10 enhanced frameshift mutation. We hypothesized that specific individual nucleotide(s) within these flanking sequences control ACVR2 frameshift mutation rates. Only the 3rd nucleotide 5' of the microsatellite, and 3rd, 4th, and 5th nucleotides 3' of the microsatellite were altered from the native flanking sequences and these locations were individually altered (sites A, B, C, and D, respectively). Constructs were cloned +1bp out-of-frame of EGFP, allowing a -1bp frameshift to express EGFP. Plasmids were stably transfected into MMR-deficient cells. Non-fluorescent cells were sorted, cultured for 35 days, and harvested for flow cytometry and DNA-sequencing. Site A (C to T) and B (G to C) in ACVR2 exon 10 decreased both heteroduplex and full mutant as much as the construct containing all 4 alterations. For ACVR2 exon 3, site A (T to C), C (A to G), and D (G to C) are responsible for increased heteroduplex formation, whereas site D is responsible for full mutant formation by ACVR2 exon 10 flanking sequences. Exonic selectivity for frameshift mutation within ACVR2's sequence context is specifically controlled by individual nucleotides flanking each microsatellite.
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16
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TGFBR2 and BAX mononucleotide tract mutations, microsatellite instability, and prognosis in 1072 colorectal cancers. PLoS One 2011; 6:e25062. [PMID: 21949851 PMCID: PMC3176811 DOI: 10.1371/journal.pone.0025062] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2011] [Accepted: 08/25/2011] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND Mononucleotide tracts in the coding regions of the TGFBR2 and BAX genes are commonly mutated in microsatellite instability-high (MSI-high) colon cancers. The receptor TGFBR2 plays an important role in the TGFB1 (transforming growth factor-β, TGF-β) signaling pathway, and BAX plays a key role in apoptosis. However, a role of TGFBR2 or BAX mononucleotide mutation in colorectal cancer as a prognostic biomarker remains uncertain. METHODOLOGY/PRINCIPAL FINDINGS We utilized a database of 1072 rectal and colon cancers in two prospective cohort studies (the Nurses' Health Study and the Health Professionals Follow-up Study). Cox proportional hazards model was used to compute mortality hazard ratio (HR), adjusted for clinical, pathological and molecular features including the CpG island methylator phenotype (CIMP), LINE-1 methylation, and KRAS, BRAF and PIK3CA mutations. MSI-high was observed in 15% (162/1072) of all colorectal cancers. TGFBR2 and BAX mononucleotide mutations were detected in 74% (117/159) and 30% (48/158) of MSI-high tumors, respectively. In Kaplan-Meier analysis as well as univariate and multivariate Cox regression analyses, compared to microsatellite stable (MSS)/MSI-low cases, MSI-high cases were associated with superior colorectal cancer-specific survival [adjusted HR, 0.34; 95% confidence interval (CI), 0.20-0.57] regardless of TGFBR2 or BAX mutation status. Among MSI-high tumors, TGFBR2 mononucleotide mutation was associated with CIMP-high independent of other variables [multivariate odds ratio, 3.57; 95% CI, 1.66-7.66; p = 0.0011]. CONCLUSIONS TGFBR2 or BAX mononucleotide mutations are not associated with the patient survival outcome in MSI-high colorectal cancer. Our data do not support those mutations as prognostic biomarkers (beyond MSI) in colorectal carcinoma.
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Abstract
Activins are the members of transforming growth factor β superfamily and act as secreted proteins; they were originally identified with a reproductive function, acting as endocrine-derived regulators of pituitary follicular stimulating hormone. In recent years, additional functions of activins have been discovered, including a regulatory role during crucial phases of growth, differentiation, and development such as wound healing, tissue repair, and regulation of branching morphogenesis. The functions of activins through activin receptors are pleiotrophic, while involving in the etiology and pathogenesis of a variety of diseases and being cell type-specific, they have been identified as important players in cancer metastasis, immune responses, inflammation, and are most likely involved in cell migration. In this chapter, we highlight the current knowledge of activin signaling and discuss the potential physiological and pathological roles of activins acting on the migration of various cell types.
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Fearon ER. Molecular genetics of colorectal cancer. ANNUAL REVIEW OF PATHOLOGY-MECHANISMS OF DISEASE 2011; 6:479-507. [PMID: 21090969 DOI: 10.1146/annurev-pathol-011110-130235] [Citation(s) in RCA: 1209] [Impact Index Per Article: 93.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Over the past three decades, molecular genetic studies have revealed some critical mutations underlying the pathogenesis of the sporadic and inherited forms of colorectal cancer (CRC). A relatively limited number of oncogenes and tumor-suppressor genes-most prominently the APC, KRAS, and p53 genes-are mutated in a sizeable fraction of CRCs, and a larger collection of genes that are mutated in subsets of CRC have begun to be defined. Together with DNA-methylation and chromatin-structure changes, the mutations act to dysregulate conserved signaling networks that exert context-dependent effects on critical cell phenotypes, including the regulation of cellular metabolism, proliferation, differentiation, and survival. Much work remains to be done to fully understand the nature and significance of the individual and collective genetic and epigenetic defects in CRC. Some key concepts for the field have emerged, two of which are emphasized in this review. Specifically, the gene defects in CRC often target proteins and pathways that exert pleiotropic effects on the cancer cell phenotype, and particular genetic and epigenetic alterations are linked to biologically and clinically distinct subsets of CRC.
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Affiliation(s)
- Eric R Fearon
- The Cancer Center, Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, 48109-2200, USA.
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19
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Bacolod MD, Barany F. Molecular profiling of colon tumors: the search for clinically relevant biomarkers of progression, prognosis, therapeutics, and predisposition. Ann Surg Oncol 2011; 18:3694-700. [PMID: 21347779 DOI: 10.1245/s10434-011-1615-5] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2010] [Indexed: 01/21/2023]
Abstract
If properly translated to clinical use, our knowledge about biomarkers may lead to a more effective way of combating colorectal cancer (CRC). Biomarkers are biomolecular, genetic, or cytogenetic attributes indicative of the disease's progression, predisposition, prognosis, or therapeutic options. For CRC, these include chromosomal instability, mutations in KRAS and TP53, loss of 18q, and elevated level of carcinoembryonic antigen (CEA), which are all associated with poor prognosis. The prognostic significance of 18q loss can be attributed to reduced expression of SMAD4, or DCC, although the chromosomal arm is actually heavily populated by genes whose downregulation correlate to worse survival. Potentially, identification of prognostic biomarkers can help the oncologist decide whether adjuvant chemotherapy is necessary after surgery. Testing for therapeutic biomarkers can be necessary if targeted therapeutics are being considered. The identification of highly penetrant predisposition markers (such as mutations in APC and MLH1) can be a lifesaver for carrier individuals, who would then have to undergo colonoscopy at an earlier age. Even sporadic CRCs may have some hereditary components, according to recent studies. Genome-wide association studies (using SNP arrays) showed that polymorphisms of certain genes can have subtle influence on CRC predisposition. Our own SNP array-based analysis suggested that long stretches of germline homozygosity (autozygosity), indicative of consanguinity, may also factor in CRC predisposition.
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Affiliation(s)
- Manny D Bacolod
- Department of Microbiology and Immunology, Weill Cornell Medical College, New York, NY, USA.
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20
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Lee SY, Chung H, Devaraj B, Iwaizumi M, Han HS, Hwang DY, Seong MK, Jung BH, Carethers JM. Microsatellite alterations at selected tetranucleotide repeats are associated with morphologies of colorectal neoplasias. Gastroenterology 2010; 139:1519-25. [PMID: 20708618 PMCID: PMC2967646 DOI: 10.1053/j.gastro.2010.08.001] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/09/2010] [Revised: 07/24/2010] [Accepted: 08/04/2010] [Indexed: 12/24/2022]
Abstract
BACKGROUND & AIMS Elevated microsatellite alterations at selected tetranucleotide repeats (EMAST) occurs during microsatellite instability (MSI) that is not associated with major defects in DNA mismatch repair (MMR) but rather the reduced (heterogenous) expression of the MMR protein hMSH3; it occurs in sporadic colorectal tumors. We examined the timing of development of EMAST during progression of colorectal neoplasias and looked for correlations between EMAST and clinical and pathology features of tumors. METHODS We evaluated tumor samples from a cohort of patients that had 24 adenomas and 84 colorectal cancers. EMAST were analyzed after DNA microdissection of matched normal and tumor samples using the polymorphic tetranucleotide microsatellite markers MYCL1, D9S242, D20S85, D8S321, and D20S82; data were compared with clinical and pathology findings. Traditional MSI analysis was performed and hMSH3 expression was measured. RESULTS Moderately differentiated adenocarcinomas and poorly differentiated adenocarcinomas had higher frequencies of EMAST (56.9% and 40.0%, respectively) than well-differentiated adenocarcinomas (12.5%) or adenomas (33.3%) (P = .040). In endoscopic analysis, ulcerated tumors had a higher frequency of EMAST (52.3%) than flat (44.0%) or protruded tumors (20.0%) (P = .049). In quantification, all tumors with >3 tetranucleotide defects lost MSH3 (>75% of cells); nuclear heterogeneity of hMSH3 occurred more frequently in EMAST-positive (40.0%) than in EMAST-negative tumors (13.2%) (P = .010). CONCLUSIONS EMAST is acquired during progression of adenoma and well-differentiated carcinomas to moderately and poorly differentiated carcinomas; it correlates with nuclear heterogeneity for hMSH3. Loss of hMSH3 corresponds with multiple tetranucleotide frameshifts. The association between EMAST and ulcerated tumors might result from increased inflammation.
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Affiliation(s)
- Sun-Young Lee
- Department of Internal Medicine, Konkuk University School of Medicine, Seoul, Korea,Department of Medicine and Moores Comprehensive Cancer Center, University of California San Diego
| | - Heekyung Chung
- Department of Medicine and Moores Comprehensive Cancer Center, University of California San Diego
| | - Bikash Devaraj
- Department of Medicine and Moores Comprehensive Cancer Center, University of California San Diego
| | - Moriya Iwaizumi
- Department of Medicine and Moores Comprehensive Cancer Center, University of California San Diego
| | - Hye Seung Han
- Department of Pathology, Konkuk University School of Medicine, Seoul, Korea
| | - Dae-Yong Hwang
- Department of Surgery, Konkuk University School of Medicine, Seoul, Korea
| | - Moo Kyung Seong
- Department of Surgery, Konkuk University School of Medicine, Seoul, Korea
| | - Barbara H. Jung
- Department of Medicine and Moores Comprehensive Cancer Center, University of California San Diego
| | - John M. Carethers
- Department of Medicine and Moores Comprehensive Cancer Center, University of California San Diego,Department of Internal Medicine, University of Michigan
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Garcia-Marcos M, Jung BH, Ear J, Cabrera B, Carethers JM, Ghosh P. Expression of GIV/Girdin, a metastasis-related protein, predicts patient survival in colon cancer. FASEB J 2010; 25:590-9. [PMID: 20974669 DOI: 10.1096/fj.10-167304] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Metastasis accounts for the majority of cancer-related deaths. Accurate prediction of metastatic potential of tumors has been elusive, and the search for clinically useful markers continues. We previously reported that GIV/Girdin triggers tumor cell migration by virtue of a C-terminal guanine-nucleotide exchange factor motif that activates Gαi. Here we identify GIV as a metastasis-related protein whose full-length transcript (GIV-fl) is expressed exclusively in highly invasive colon, breast, and pancreatic carcinoma cells and not in their poorly invasive counterparts. A prospective, exploratory biomarker study conducted on a cohort of 56 patients with stage II colorectal cancer revealed a significant correlation between GIV-fl expression in tumor epithelium and shortened metastasis-free survival. Survival rate for patients with GIV-fl-positive tumors is significantly reduced compared with the patients with GIV-fl-negative tumors [P<0.0001; hazard ratio=0.076; CI=0.052-0.30 (95%)]. At the 5-yr mark, survival is 100% in the GIV-fl-negative group and 62 ± 9% (mean±SE; P=6×10(-5)) in the GIV-fl-positive group. Furthermore, GIV-fl expression predicts a risk of mortality independent of the microsatellite stability status, a well-established prognosticator of colorectal cancers. We conclude that GIV-fl is a novel metastasis-related protein and an independent adverse prognosticator that may serve as a useful adjunct to traditional staging strategies in colorectal carcinoma.
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Affiliation(s)
- Mikel Garcia-Marcos
- Department of Cellular and Molecular Medicine, George E. Palade Laboratories, University of California, San Diego School of Medicine, La Jolla, CA 92093-0651, USA
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Chung H, Lopez CG, Holmstrom J, Young DJ, Lai JF, Ream-Robinson D, Carethers JM. Both microsatellite length and sequence context determine frameshift mutation rates in defective DNA mismatch repair. Hum Mol Genet 2010; 19:2638-47. [PMID: 20418486 DOI: 10.1093/hmg/ddq151] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
It is generally accepted that longer microsatellites mutate more frequently in defective DNA mismatch repair (MMR) than shorter microsatellites. Indeed, we have previously observed that the A10 microsatellite of transforming growth factor beta type II receptor (TGFBR2) frameshifts -1 bp at a faster rate than the A8 microsatellite of activin type II receptor (ACVR2), although both genes become frameshift-mutated in >80% of MMR-defective colorectal cancers. To experimentally determine the effect of microsatellite length upon frameshift mutation in gene-specific sequence contexts, we altered the microsatellite length within TGFBR2 exon 3 and ACVR2 exon 10, generating A7, A10 and A13 constructs. These constructs were cloned 1 bp out of frame of EGFP, allowing a -1 bp frameshift to drive EGFP expression, and stably transfected into MMR-deficient cells. Subsequent non-fluorescent cells were sorted, cultured for 7-35 days and harvested for EGFP analysis and DNA sequencing. Longer microsatellites within TGFBR2 and ACVR2 showed significantly higher mutation rates than shorter ones, with TGFBR2 A13, A10 and A7 frameshifts measured at 22.38x10(-4), 2.17x10(-4) and 0.13x10(-4), respectively. Surprisingly, shorter ACVR2 constructs showed three times higher mutation rates at A7 and A10 lengths than identical length TGFBR2 constructs but comparably lower at the A13 length, suggesting influences from both microsatellite length as well as the sequence context. Furthermore, the TGFBR2 A13 construct mutated into 33% A11 sequences (-2 bp) in addition to expected A12 (-1 bp), indicating that this construct undergoes continual subsequent frameshift mutation. These data demonstrate experimentally that both the length of a mononucleotide microsatellite and its sequence context influence mutation rate in defective DNA MMR.
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Affiliation(s)
- Heekyung Chung
- Department of Medicine, University of California, San Diego, CA, USA
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Flanking sequence specificity determines coding microsatellite heteroduplex and mutation rates with defective DNA mismatch repair (MMR). Oncogene 2010; 29:2172-80. [PMID: 20140012 PMCID: PMC4028169 DOI: 10.1038/onc.2009.508] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
The activin type II receptor (ACVR2) contains 2 identical microsatellites in exon 3 and 10, but only the exon 10 microsatellite is frameshifted in MMR-defective colonic tumors. The reason for this selectivity is not known. We hypothesized that ACVR2 frameshifts were influenced by DNA sequences surrounding the microsatellite. We constructed plasmids in which exon 3 or 10 of ACVR2 were cloned +1bp out-of-frame of EGFP, allowing −1bp frameshift to express EGFP. Plasmids were stably-transfected into MMR-deficient cells, subsequent non-fluorescent cells sorted, cultured, and harvested for mutation analysis. We swapped DNA sequences flanking the exon 3 and 10 microsatellites to test our hypothesis. Native ACVR2 exon 3 and 10 microsatellites underwent heteroduplex formation (A7/T8) in hMLH1−/− cells, but only exon 10 microsatellites fully mutated (A7/T7) in both hMLH1−/− and hMSH6−/− backgrounds, showing selectivity for exon 10 frameshifts and inability of exon 3 heteroduplexes to fully mutate. Substituting nucleotides flanking the exon 3 microsatellite for nucleotides flanking the exon 10 microsatellite significantly reduced heteroduplex and full mutation in hMLH1−/− cells. When the exon 3 microsatellite was flanked by nucleotides normally surrounding the exon 10 microsatellite, fully-mutant exon 3 frameshifts appeared. Mutation selectivity for ACVR2 lies partly with flanking nucleotides surrounding each microsatellite.
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Carethers JM. Secondary Prevention of Colorectal Cancer: Is There an Optimal Follow-up for Patients with Colorectal Cancer? CURRENT COLORECTAL CANCER REPORTS 2010; 6:24-29. [PMID: 20157368 PMCID: PMC2817804 DOI: 10.1007/s11888-009-0038-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Secondary prevention of colorectal cancer, as opposed to primary prevention, indicates that a person has already had the disease and there are steps being taken to prevent cancer recurrence, usually as metachronous tumors. This generally involves annual surveillance with colonoscopy after surgical removal of the initial cancer if some aspect of the colon remains. However, some familial cases may involve other modalities, such as cyclooxygenase inhibitors, as an adjunct after the initial operation. Genetic testing in suspected familial cases may identify candidates for secondary prevention. The timing for secondary prevention is critical to prevent recurrent advanced disease, which is detrimental to patient survival. Recommendations are often empiric, but some cases are based on the biological behavior of the tumor. Close follow-up with a competent health care provider, such as a gastroenterologist, is necessary to help prevent recurrence.
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Affiliation(s)
- John M Carethers
- Department of Internal Medicine, University of Michigan, 3101 Taubman Center, 1500 East Medical Center Drive, Ann Arbor, MI 48109 USA
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Activin signaling in microsatellite stable colon cancers is disrupted by a combination of genetic and epigenetic mechanisms. PLoS One 2009; 4:e8308. [PMID: 20011542 PMCID: PMC2789408 DOI: 10.1371/journal.pone.0008308] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2009] [Accepted: 11/20/2009] [Indexed: 11/19/2022] Open
Abstract
Background Activin receptor 2 (ACVR2) is commonly mutated in microsatellite unstable (MSI) colon cancers, leading to protein loss, signaling disruption, and larger tumors. Here, we examined activin signaling disruption in microsatellite stable (MSS) colon cancers. Methods Fifty-one population-based MSS colon cancers were assessed for ACVR1, ACVR2 and pSMAD2 protein. Consensus mutation-prone portions of ACVR2 were sequenced in primary cancers and all exons in colon cancer cell lines. Loss of heterozygosity (LOH) was evaluated for ACVR2 and ACVR1, and ACVR2 promoter methylation by methylation-specific PCR and bisulfite sequencing and chromosomal instability (CIN) phenotype via fluorescent LOH analysis of 3 duplicate markers. ACVR2 promoter methylation and ACVR2 expression were assessed in colon cancer cell lines via qPCR and IP-Western blots. Re-expression of ACVR2 after demethylation with 5-aza-2′-deoxycytidine (5-Aza) was determined. An additional 26 MSS colon cancers were assessed for ACVR2 loss and its mechanism, and ACVR2 loss in all tested cancers correlated with clinicopathological criteria. Results Of 51 MSS colon tumors, 7(14%) lost ACVR2, 2 (4%) ACVR1, and 5(10%) pSMAD2 expression. No somatic ACVR2 mutations were detected. Loss of ACVR2 expression was associated with LOH at ACVR2 (p<0.001) and ACVR2 promoter hypermethylation (p<0.05). ACVR2 LOH, but not promoter hypermethylation, correlated with CIN status. In colon cancer cell lines with fully methylated ACVR2 promoter, loss of ACVR2 mRNA and protein expression was restored with 5-Aza treatment. Loss of ACVR2 was associated with an increase in primary colon cancer volume (p<0.05). Conclusions Only a small percentage of MSS colon cancers lose expression of activin signaling members. ACVR2 loss occurs through LOH and ACVR2 promoter hypermethylation, revealing distinct mechanisms for ACVR2 inactivation in both MSI and MSS subtypes of colon cancer.
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Tougeron D, Fauquembergue E, Rouquette A, Le Pessot F, Sesboüé R, Laurent M, Berthet P, Mauillon J, Di Fiore F, Sabourin JC, Michel P, Tosi M, Frébourg T, Latouche JB. Tumor-infiltrating lymphocytes in colorectal cancers with microsatellite instability are correlated with the number and spectrum of frameshift mutations. Mod Pathol 2009; 22:1186-95. [PMID: 19503063 DOI: 10.1038/modpathol.2009.80] [Citation(s) in RCA: 124] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Colorectal cancers with microsatellite instability are characterized by an important density of tumor-infiltrating lymphocytes and a good prognosis. Microsatellite instability results from the inactivation of the DNA mismatch repair system and induces secondary somatic frameshift mutations within target genes harboring repeat sequences in their coding frame. By disrupting the open reading frame, frameshift mutations can result in the appearance of potentially immunogenic neopeptides. To determine the frameshift mutations inducing a T-cell response during the development of a tumor with microsatellite instability, we studied in 61 colorectal cancer patients with microsatellite instability, using a fluorescent multiplex PCR comparative analysis, the relative frequency of frameshift mutations within 19 target genes and analyzed the correlation of these frameshift mutations with the density of CD3+ tumor-infiltrating lymphocytes. The four most frequently mutated genes were ACVR2 (92%), TAF1B (84%), ASTE1/HT001 (80%) and TGFBR2 (77%). The vast majority (95%) of the tumors exhibited at least three frameshift mutations, and the number of frameshift mutations was associated with tumor progression (TNM stage, wall invasion and tumor diameter). Tumor-infiltrating lymphocyte density was associated with the overall number of frameshift mutations and with the presence of frameshift mutations within two target genes, namely ASTE1/HT001 and PTEN. These results strongly argue for the clinical relevance of immunotherapy of colorectal cancers with microsatellite instability.
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Affiliation(s)
- David Tougeron
- Inserm, U614, Faculty of Medicine, Institute for Medical Research, Rouen, Northwest Cancéropôle, France
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Chow JYC, Cabral JA, Chang J, Carethers JM. TGFbeta modulates PTEN expression independently of SMAD signaling for growth proliferation in colon cancer cells. Cancer Biol Ther 2008; 7:1694-9. [PMID: 18769113 DOI: 10.4161/cbt.7.10.6665] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Signaling pathways enabling transforming growth factor-beta (TGFbeta)'s conversion from a tumor suppressor to a tumor promoter are not well characterized. TGFbeta utilizes intracellular SMADs to mediate growth suppression; however, TGFbeta-induced proliferative pathways may become more apparent when SMAD signaling is abrogated. Here, we determined regulation of the tumor suppressor PTEN by TGFbeta utilizing SMAD4-null colon cancer cells. TGFbeta downregulated PTEN mRNA and simultaneously induced growth proliferation. TGFbeta also induced both SMAD2 and SMAD3 nuclear translocation, but only triggered SMAD2-specific transcriptional activity in the absence of SMAD4. Interference of SMAD2 with DN-SMAD2 enhanced TGFbeta-induced cell proliferation, but downregulation of PTEN expression by TGFbeta was unaffected. TGFbeta increased PI3K tyrosine phosphorylation, and inhibition of PI3K pharmacologically or by DN-p85 transfection reversed both TGFbeta-induced PTEN suppression and TGFbeta-induced cell proliferation. Thus, TGFbeta activates PI3K to downregulate PTEN for enhancement of cell proliferation that is independent of SMAD proteins.
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Affiliation(s)
- Jimmy Y C Chow
- Department of Medicine, University of California San Diego, La Jolla, CA 92093-0063, USA
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Chung H, Young DJ, Lopez CG, Le TAT, Lee JK, Ream-Robinson D, Huang SC, Carethers JM. Mutation rates of TGFBR2 and ACVR2 coding microsatellites in human cells with defective DNA mismatch repair. PLoS One 2008; 3:e3463. [PMID: 18941508 PMCID: PMC2565065 DOI: 10.1371/journal.pone.0003463] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2008] [Accepted: 09/25/2008] [Indexed: 12/21/2022] Open
Abstract
Microsatellite instability promotes colonic tumorigenesis through generating frameshift mutations at coding microsatellites of tumor suppressor genes, such as TGFBR2 and ACVR2. As a consequence, signaling through these TGFβ family receptors is abrogated in DNA Mismatch repair (MMR)-deficient tumors. How these mutations occur in real time and mutational rates of these human coding sequences have not previously been studied. We utilized cell lines with different MMR deficiencies (hMLH1−/−, hMSH6−/−, hMSH3−/−, and MMR-proficient) to determine mutation rates. Plasmids were constructed in which exon 3 of TGFBR2 and exon 10 of ACVR2 were cloned +1 bp out of frame, immediately after the translation initiation codon of an enhanced GFP (EGFP) gene, allowing a −1 bp frameshift mutation to drive EGFP expression. Mutation-resistant plasmids were constructed by interrupting the coding microsatellite sequences, preventing frameshift mutation. Stable cell lines were established containing portions of TGFBR2 and ACVR2, and nonfluorescent cells were sorted, cultured for 7–35 days, and harvested for flow cytometric mutation detection and DNA sequencing at specific time points. DNA sequencing revealed a −1 bp frameshift mutation (A9 in TGFBR2 and A7 in ACVR2) in the fluorescent cells. Two distinct fluorescent populations, M1 (dim, representing heteroduplexes) and M2 (bright, representing full mutants) were identified, with the M2 fraction accumulating over time. hMLH1 deficiency revealed 11 (5.91×10−4) and 15 (2.18×10−4) times higher mutation rates for the TGFBR2 and ACVR2 microsatellites compared to hMSH6 deficiency, respectively. The mutation rate of the TGFBR2 microsatellite was ∼3 times higher in both hMLH1 and hMSH6 deficiencies than the ACVR2 microsatellite. The −1 bp frameshift mutation rates of TGFBR2 and ACVR2 microsatellite sequences are dependent upon the human MMR background.
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Affiliation(s)
- Heekyung Chung
- Department of Medicine, University of California San Diego, La Jolla, California, United States of America
| | - Dennis J. Young
- Rebecca and John Moores Comprehensive Cancer Center, University of California San Diego, La Jolla, California, United States of America
| | - Claudia G. Lopez
- Department of Medicine, University of California San Diego, La Jolla, California, United States of America
| | - Thuy-Anh T. Le
- Department of Medicine, University of California San Diego, La Jolla, California, United States of America
| | - Jeffrey K. Lee
- Department of Medicine, University of California San Diego, La Jolla, California, United States of America
| | - Deena Ream-Robinson
- Department of Medicine, University of California San Diego, La Jolla, California, United States of America
| | - Sherry C. Huang
- Department of Pediatrics, University of California San Diego, La Jolla, California, United States of America
| | - John M. Carethers
- Department of Medicine, University of California San Diego, La Jolla, California, United States of America
- Rebecca and John Moores Comprehensive Cancer Center, University of California San Diego, La Jolla, California, United States of America
- VA San Diego Healthcare System, San Diego, California, United States of America
- * E-mail:
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Genomic and epigenetic instability in colorectal cancer pathogenesis. Gastroenterology 2008; 135:1079-99. [PMID: 18773902 PMCID: PMC2866182 DOI: 10.1053/j.gastro.2008.07.076] [Citation(s) in RCA: 680] [Impact Index Per Article: 42.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/01/2008] [Revised: 07/07/2008] [Accepted: 07/28/2008] [Indexed: 12/11/2022]
Abstract
Colorectal cancer arises as a consequence of the accumulation of genetic alterations (gene mutations, gene amplification, and so on) and epigenetic alterations (aberrant DNA methylation, chromatin modifications, and so on) that transform colonic epithelial cells into colon adenocarcinoma cells. The loss of genomic stability and resulting gene alterations are key molecular pathogenic steps that occur early in tumorigenesis; they permit the acquisition of a sufficient number of alterations in tumor suppressor genes and oncogenes that transform cells and promote tumor progression. Two predominant forms of genomic instability that have been identified in colon cancer are microsatellite instability and chromosome instability. Substantial progress has been made to identify causes of chromosomal instability in colorectal cells and to determine the effects of the different forms of genomic instability on the biological and clinical behavior of colon tumors. In addition to genomic instability, epigenetic instability results in the aberrant methylation of tumor suppressor genes. Determining the causes and roles of genomic and epigenomic instability in colon tumor formation has the potential to yield more effective prevention strategies and therapeutics for patients with colorectal cancer.
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Muñoz NM, Baek JY, Grady WM. TGF-beta has paradoxical and context dependent effects on proliferation and anoikis in human colorectal cancer cell lines. Growth Factors 2008; 26:254-62. [PMID: 18651288 PMCID: PMC2694855 DOI: 10.1080/08977190802291667] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Transforming growth factor-beta (TGF-beta) is a pluripotent cytokine that can have both tumor suppressing and tumor promoting effects on epithelial cells. It is unclear what determines when TGF-beta and its signaling pathway act predominantly as a tumor suppressor pathway or as a tumor-promoter pathway and whether TGF-beta can have both classes of effects concurrently on a cell. We investigated the effect of TGF-beta on anoikis in colorectal cancer cell lines sensitive to TGF-beta-mediated growth inhibition to determine if the context of the cells could be one of the factors that would affect whether TGF-beta exerts tumor suppressor or oncogene activity on colon cancer cells. We observed variable effects of TGF-beta on anoikis in these cell lines, even though they all are growth-inhibited by TGF-beta. Thus, we show that TGF-beta has variable effects on anoikis in colon cancer cell lines that likely reflects the effects of concurrent gene mutations in the cancer cells and the activation state of the signaling pathways controlled by these genes.
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Affiliation(s)
- Nina M Muñoz
- Department of Cancer Biology, Vanderbilt University Graduate School, Nashville, TN, USA
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The efficacy of adjuvant chemotherapy with 5-fluorouracil in colorectal cancer depends on the mismatch repair status. Eur J Cancer 2008; 45:365-73. [PMID: 18722765 DOI: 10.1016/j.ejca.2008.07.016] [Citation(s) in RCA: 158] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2008] [Revised: 06/30/2008] [Accepted: 07/01/2008] [Indexed: 12/26/2022]
Abstract
AIMS The aim of this study is to evaluate if mismatch repair (MMR) defective colorectal cancer has a different response to adjuvant 5-fluorouracil (5-FU) chemotherapy in a cohort of patients prospectively followed during 5 years. METHODS The cohort included 754 surgically treated patients with colorectal cancer. MMR status was diagnosed by MLH1 and MSH2 immunohistochemistry and microsatellite instability analysis. Median follow-up was 49.2 months (range 1-73). At inclusion, 505 patients were diagnosed as TNM II or III stage, analysis of the efficacy of adjuvant chemotherapy was made on this population. Adjuvant chemotherapy was applied to 248 patients (98.2% 5-FU based). RESULTS MMR deficiency was found in 76 patients (10.1%). No differences were found in overall survival (log-rank p=0.3) or disease-free survival (log-rank p=0.3) regarding MMR status. Adjuvant chemotherapy improves survival in patients in the II or III stage, but this improvement is only evident in patients with MMR-competent tumours (log-rank p=0.00001). Survival of patients with MMR-defective tumours does not improve with adjuvant chemotherapy (log-rank p=0.7). A multivariate analysis showed an independent effect of the interaction between MMR status and adjuvant chemotherapy (Hazard ratio 2.04; 95% confidence interval: 1.42-2.93). CONCLUSION In a cohort of colorectal cancer patients, those with MMR-deficient tumours seem not to benefit from 5-FU-based chemotherapy.
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Biasi F, Mascia C, Poli G. The contribution of animal fat oxidation products to colon carcinogenesis, through modulation of TGF-beta1 signaling. Carcinogenesis 2008; 29:890-4. [PMID: 18453540 DOI: 10.1093/carcin/bgn106] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
It is now unanimously accepted that neoplastic cells tend to become less susceptible to the growth regulatory effects of transforming growth factor-beta1 (TGF-beta1), mainly because of reduced expression and/or activity of TGF-beta1-specific receptors, as reported for many human cancers including colon cancer. Consequently, a sustained increase of TGF-beta1 in the intestinal mucosa, like that caused by inflammatory processes and/or high dietary intake of animal fat, might become crucial for the progression of a neoplastic clone. In fact, this proapoptotic and prodifferentiating cytokine could eliminate neoplastic cells still susceptible to TGF-beta1's antiproliferative action (TGF-beta1 receptor-positive cells), indirectly favoring the expansion of TGF-beta1 resistant ones (TGF-beta1 receptors deficient or negative cells). The actual concentration of TGF-beta1 in the colonic mucosa undergoing neoplastic transformation is still debated, and the phase of the relevant carcinogenetic process in which a reduced susceptibility to this antiproliferative molecule first occurs has not been precisely established yet. However, no doubt that TGF-beta1 level and activity may be upregulated in cells of the macrophage lineage by animal fat oxidation products, such as oxysterols and aldehydes, as reviewed here. But phagocytes as well as fibroblasts constitutively express TGF-beta1 and are accumulating in tumor-associated stroma. Thus, upregulation of this cytokine system within colonic tumor-associated stroma by excess dietary intake of cholesterol and n-6 polyunsaturated fatty acids appears as a primary mechanism of cancer progression at least in neoplastic lesions of the digestive tract.
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Affiliation(s)
- Fiorella Biasi
- Department of Clinical and Biological Sciences, University of Turin, San Luigi Gonzaga Hospital, Regione Gonzole 10, 10043 Orbassano, Torino, Italy
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33
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Bone morphogenetic protein and activin signaling in colorectal cancer. CURRENT COLORECTAL CANCER REPORTS 2008. [DOI: 10.1007/s11888-008-0013-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
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34
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Falchetti M, Saieva C, Lupi R, Masala G, Rizzolo P, Zanna I, Ceccarelli K, Sera F, Mariani-Costantini R, Nesi G, Palli D, Ottini L. Gastric cancer with high-level microsatellite instability: target gene mutations, clinicopathologic features, and long-term survival. Hum Pathol 2008; 39:925-32. [PMID: 18440592 DOI: 10.1016/j.humpath.2007.10.024] [Citation(s) in RCA: 103] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/18/2007] [Revised: 10/23/2007] [Accepted: 10/25/2007] [Indexed: 12/15/2022]
Abstract
Gastric cancer is one of the leading causes of cancer death worldwide, and although the incidence has decreased in Western countries, specific high-risk areas are present in Italy. Gastric cancer with high-level microsatellite instability (MSI-H) represents a well-defined subset of carcinomas showing distinctive clinicopathologic features. We examined clinicopathologic associations and long-term survival in a series of 159 gastric cancer cases from a high-risk population in Tuscany (central Italy). MSI-H was associated with antral location of the tumor (P = .001), intestinal type according to Lauren classification (P = .002), expanding type according to Ming classification (P = .0001), and mucinous histologic type according to the Japanese Research Society for Gastric Cancer classification (P = .002). In addition, MSI-H was strongly associated with a higher survival at 15 years (P = .01) and with loss of hMLH1 expression, evaluated by immunohistochemistry (P = .001). Multivariate analyses showed a significant association between the absence of hMLH1 reactivity and the expanding tumor type (P = .002). We also investigated the MSI-H-related genetic changes by analyzing coding repeats within target genes involved in pathways that control cell growth (TGFbetaRII, IGFIIR, RIZ, TCF4, DP2), apoptosis (BAX, BCL10, FAS, CASPASE5, APAF1), and DNA repair genes (hMSH6, hMSH3, MED1, RAD50, BLM, ATR, BRCA2, MRE11). Gastric cancer cases with MSI-H were found to accumulate heterozygous mutations affecting multiple molecular pathways and multiple genes within each pathway. Intriguingly, in this subset, TGFbetaRII mutations appeared to be inversely related to BLM mutations (P = .006), whereas RAD50 mutation carriers showed significantly reduced survival (P = .03).
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Affiliation(s)
- Mario Falchetti
- Department of Experimental Medicine, University La Sapienza, 00161 Rome, Italy
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Abstract
Molecular classification of colorectal cancer is evolving. As our understanding of colorectal carcinogenesis improves, we are incorporating new knowledge into the classification system. In particular, global genomic status [microsatellite instability (MSI) status and chromosomal instability (CIN) status] and epigenomic status [CpG island methylator phenotype (CIMP) status] play a significant role in determining clinical, pathological and biological characteristics of colorectal cancer. In this review, we discuss molecular classification and molecular correlates based on MSI status and CIMP status in colorectal cancer. Studying molecular correlates is important in cancer research because it can 1) provide clues to pathogenesis, 2) propose or support the existence of a new molecular subtype, 3) alert investigators to be aware of potential confounding factors in association studies, and 4) suggest surrogate markers in clinical or research settings.
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Affiliation(s)
- Shuji Ogino
- Department of Pathology, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts 02115, USA.
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Malesci A, Laghi L, Bianchi P, Delconte G, Randolph A, Torri V, Carnaghi C, Doci R, Rosati R, Montorsi M, Roncalli M, Gennari L, Santoro A. Reduced likelihood of metastases in patients with microsatellite-unstable colorectal cancer. Clin Cancer Res 2007; 13:3831-9. [PMID: 17606714 DOI: 10.1158/1078-0432.ccr-07-0366] [Citation(s) in RCA: 185] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
PURPOSE The outcome of patients with colorectal cancer is more favorable when the tumor exhibits high-frequency microsatellite instability (MSI). Although associated with earlier-stage tumors, MSI has been proposed as an independent predictor of survival. We tested the prognostic value of MSI in a large series of patients diagnosed with colorectal cancer in the last decade. EXPERIMENTAL DESIGN The survival of 893 consecutive patients with colorectal cancer characterized by microsatellite status was analyzed. The 89 (10%) patients with MSI cancer were classified according to tumor mismatch repair (MMR) defect, MMR germ-line mutation, hMLH1 and p16 promoter methylation, BRAF and K-ras mutations, and frameshifts of target genes. RESULTS The colorectal cancer-specific survival was significantly (P = 0.02) better in patients with MSI cancer than in those with stable tumor (MSS). MSI did not predict a significantly lower risk of cancer-related death if tumor stage was included in the multivariate analysis [hazard ratio, 0.72; 95% confidence interval (95% CI), 0.40-1.29; P = 0.27]. Instead, MSI was strongly associated with a decreased likelihood of lymph node (odds ratio, 0.31; 95% CI, 0.17-0.56; P < 0.001) and distant organ (odds ratio, 0.13; 95% CI, 0.05-0.33; P < 0.001) metastases at diagnosis, independently of tumor pathologic features. Molecular predictors of reduced metastatic risk, and then of more favorable prognosis, included TGFbetaRII mutation for all MSI tumors, hMSH2 deficiency for hereditary non-polyposis colorectal cancer, and absence of p16 methylation for sporadic hMLH1-deficient cancers. CONCLUSIONS Tumor MSI is a stage-dependent predictor of survival in patients with colorectal cancer. The decreased likelihood of metastases in patients with MSI cancer is associated with specific genetic and epigenetic changes of the primary tumor.
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Affiliation(s)
- Alberto Malesci
- Department of Gastroenterology, IRCCS Istituto Clinico Humanitas, Rozzano, Milan, Italy.
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Grady WM. Transforming growth factor β signaling in colorectal cancer. CURRENT COLORECTAL CANCER REPORTS 2007. [DOI: 10.1007/s11888-007-0002-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Jung BH, Beck SE, Cabral J, Chau E, Cabrera BL, Fiorino A, Smith EJ, Bocanegra M, Carethers JM. Activin type 2 receptor restoration in MSI-H colon cancer suppresses growth and enhances migration with activin. Gastroenterology 2007; 132:633-44. [PMID: 17258738 PMCID: PMC4154562 DOI: 10.1053/j.gastro.2006.11.018] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/15/2006] [Accepted: 11/09/2006] [Indexed: 12/02/2022]
Abstract
BACKGROUND & AIMS Colon cancers with high-frequency microsatellite instability (MSI-H) develop frameshift mutations in tumor suppressors as part of their pathogenesis. ACVR2 is mutated at its exon 10 polyadenine tract in >80% of MSI-H colon cancers, coinciding with loss of protein. ACVR2 transmits the growth effects of activin via phosphorylation of SMAD proteins to affect gene transcription. The functional effect of activin in colon cancers has not been studied. We developed and characterized a cell model in which we studied how activin signaling affects growth. METHODS hMLH1 and ACVR2 mutant HCT116 cells were previously stably transferred with chromosome 2 (HCT116+chr2), restoring a single regulated copy of wild-type ACVR2 but not hMLH1. Both HCT116+chr2 and parental HCT116 cells (as well as HEC59 and ACVR2 and hMSH2 complemented HEC59+chr2 cells) were assessed for genetic complementation and biologic function. RESULTS HCT116+chr2 cells and HEC59+chr2 cells, but not ACVR2-mutant HCT116 or HEC59 cells, acquired wild-type ACVR2 as well as expression of ACVR2 wild-type messenger RNA. Complemented ACVR2 protein complexed with ACVR1 with activin treatment, generating nuclear phosphoSMAD2 and activin-specific gene transcription. ACVR2-restored cells showed decreased growth and reduced S phase but increased cellular migration following activin treatment. ACVR2 small interfering RNA reversed these effects in complemented cells. CONCLUSIONS ACVR2-complemented MSI-H colon cancers restore activin-SMAD signaling, decrease growth, and slow their cell cycle following ligand stimulation but show increased cellular migration. Activin is growth suppressive and enhances migration similar to transforming growth factor beta in colon cancer, indicating that abrogation of the effects of activin contribute to the pathogenesis of MSI-H colon cancers.
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MESH Headings
- Active Transport, Cell Nucleus
- Activin Receptors, Type I/metabolism
- Activin Receptors, Type II/drug effects
- Activin Receptors, Type II/genetics
- Activin Receptors, Type II/metabolism
- Activins/metabolism
- Activins/pharmacology
- Adaptor Proteins, Signal Transducing
- Autocrine Communication
- Carrier Proteins/metabolism
- Cell Movement/drug effects
- Cell Nucleus/metabolism
- Cell Proliferation/drug effects
- Chromosomes, Human, Pair 2/genetics
- Colonic Neoplasms/genetics
- Colonic Neoplasms/metabolism
- Colonic Neoplasms/pathology
- Dose-Response Relationship, Drug
- Gene Expression Regulation, Neoplastic
- HCT116 Cells
- Humans
- Microsatellite Instability
- MutL Protein Homolog 1
- Mutation
- Nuclear Proteins/metabolism
- Phosphorylation
- Proto-Oncogene Proteins c-myc/metabolism
- Signal Transduction/drug effects
- Smad2 Protein/metabolism
- Time Factors
- Transcriptional Activation
- Transfection
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Affiliation(s)
- Barbara H Jung
- Department of Medicine, University of California, San Diego, La Jolla 92093-0063, USA
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Ogino S, Kawasaki T, Ogawa A, Kirkner GJ, Loda M, Fuchs CS. TGFBR2 mutation is correlated with CpG island methylator phenotype in microsatellite instability-high colorectal cancer. Hum Pathol 2007; 38:614-20. [PMID: 17270239 DOI: 10.1016/j.humpath.2006.10.005] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/18/2006] [Revised: 10/06/2006] [Accepted: 10/06/2006] [Indexed: 12/25/2022]
Abstract
The transforming growth factor-beta receptor type 2 gene (TGFBR2) is mutated in most microsatellite instability-high (MSI-H) colorectal cancers. Promoter methylation of RUNX3 (runt-related transcription factor 3; encoding a transcription factor downstream of the TGF-beta pathway) is observed in colorectal cancer with CpG island methylator phenotype (CIMP), which is characterized by extensive promoter methylation and is associated with MSI-H and BRAF mutations. However, no study to date has examined interrelationship between TGFBR2 mutation, RUNX3 methylation, and CIMP in colorectal cancer. Using 144 MSI-H colorectal cancers derived from 2 large prospective cohort studies, we analyzed a mononucleotide repeat of TGFBR2 and quantified DNA methylation (by MethyLight technology) in 8 CIMP-specific promoters (RUNX3, CACNA1G [calcium channel, voltage-dependent, T type alpha-1G subunit], CDKN2A [p16], CRABP1 [cellular retinoic acid binding protein 1], IGF2 [insulin-like growth factor 2], MLH1, NEUROG1 [neurogenin 1], and SOCS1 [suppressor of cytokine signaling 1]). Among the 144 MSI-H tumors, the presence of TGFBR2 mutation (overall 72% frequency) was correlated positively with CIMP-high (with >/=6/8 methylated promoters; P < .0001), RUNX3 methylation (P = .0004), BRAF mutation (P = .0006), and right colon (P = .05); inversely with KRAS mutation (P = .006); but not significantly with sex, tumor differentiation, and p53 status (assessed by immunohistochemistry). After stratification by sex, location, tumor differentiation, RUNX3 status, KRAS/BRAF status, or p53 status, CIMP-high was persistently correlated with TGFBR2 mutation. In contrast, RUNX3, KRAS, or BRAF status was no longer correlated with TGFBR2 mutation after stratification by CIMP status. In conclusion, TGFBR2 mutation is associated with CIMP-high and indirectly with RUNX3 methylation. Our findings emphasize the importance of analyzing global epigenomic status (for which CIMP status is a surrogate marker) when correlating a single epigenetic event (eg, RUNX3 methylation) with any other molecular or clinicopathologic variables.
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Affiliation(s)
- Shuji Ogino
- Department of Pathology, Brigham and Women's Hospital, Boston, MA 02115, USA.
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Beck SE, Jung BH, Rosario ED, Gomez J, Carethers JM. BMP-induced growth suppression in colon cancer cells is mediated by p21WAF1 stabilization and modulated by RAS/ERK. Cell Signal 2007; 19:1465-72. [PMID: 17317101 PMCID: PMC3444522 DOI: 10.1016/j.cellsig.2007.01.017] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2006] [Revised: 01/15/2007] [Accepted: 01/16/2007] [Indexed: 11/29/2022]
Abstract
Bone morphogenetic proteins (BMPs) regulate cell differentiation, proliferation, and apoptosis through a canonical SMAD signaling cascade. Absence of BMP signaling causes the formation of intestinal juvenile polyps in the colon cancer-prone syndrome familial juvenile polyposis. As sporadic colon cancers appear to have intact BMP signaling, we evaluated if K-RAS, driving a mitogenic pathway frequently activated in colon cancer, negatively affects BMP growth suppression. We treated non-tumorigenic but activated RAS/ERK FET cells with BMP2, and in combination with pharmacological or genetic inhibition of RAS/ERK, examined BMP-SMAD signaling, transcriptional activity, and cell growth, and also assessed p21(WAF1) mRNA, transcriptional activation, and protein levels. BMP2 increased nuclear phospho-SMAD1 2-fold, which increased another 2-3 fold when RAS/ERK was inhibited. BMP2 increased BMP-specific SMAD transcriptional activity 2-fold over control and decreased cell growth, but inhibition of RAS/ERK further enhanced BMP-specific transcriptional activity by an additional 1.5-2 fold and enhanced growth suppression by 20%. BMP-induced growth suppression is mediated in part by p21(WAF1), not by transcriptional upregulation but by improved p21 protein stability, which is inhibited by RAS/ERK. In colon cancer cells, BMP-SMAD signaling and growth suppression is facilitated by p21(WAF1) but modulated by oncogenic K-RAS to reduce the growth suppression directed by this pathway.
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Affiliation(s)
- Stayce E. Beck
- Department of Medicine, University of California, San Diego, United States
- Biomedical Sciences Program, University of California, San Diego, United States
| | - Barbara H. Jung
- Department of Medicine, University of California, San Diego, United States
- Rebecca and John Moores Comprehensive Cancer Center, University of California, San Diego, United States
- VA San Diego Healthcare System, United States
| | - Eunice Del Rosario
- Department of Medicine, University of California, San Diego, United States
| | - Jessica Gomez
- Department of Medicine, University of California, San Diego, United States
- Rebecca and John Moores Comprehensive Cancer Center, University of California, San Diego, United States
| | - John M. Carethers
- Department of Medicine, University of California, San Diego, United States
- Rebecca and John Moores Comprehensive Cancer Center, University of California, San Diego, United States
- Biomedical Sciences Program, University of California, San Diego, United States
- VA San Diego Healthcare System, United States
- Corresponding author. University of California, San Diego, Division of Gastroenterology, UC303, MC 0063, 9500 Gilman Drive, La Jolla, CA 92093-0063, United States. Tel.: +1 858 534 3320; fax: +1 858 534 3337., (J.M. Carethers)
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Current World Literature. Curr Opin Oncol 2007; 19:65-9. [PMID: 17133115 DOI: 10.1097/cco.0b013e328012d5fa] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Abstract
Chemotherapy for colorectal cancer is currently offered to patients based on the stage of their cancer, and there is evidence to show an overall survival benefit with 5-fluorouracil-based (5-FU) therapy for patients with lymph node metastasis who receive it. The pathogenesis of colorectal cancer involves genomic instability, with about 15% of tumors demonstrating a form of genomic instability called high-frequency microsatellite instability (MSI-H) and due to loss of DNA mismatch repair function, and the remainder of colorectal tumors lacking MSI-H with retained DNA mismatch repair function and called microsatellite stable (MSS), with a large proportion of these tumors demonstrating another form of genomic instability called chromosomal instability. There is now evidence to show that the form of genomic instability that is present in a patient's colorectal cancer may predict a survival benefit from 5-FU. In particular, patients whose colorectal tumors have MSI-H do not gain a survival benefit with 5-FU as compared to patients with MSS tumors. In vitro evidence supports these findings, as MSI-H colon cancer cell lines are more resistant to 5-FU compared to MSS cell lines. More specifically, components of the DNA mismatch repair system have been shown to recognize and bind to 5-FU that becomes incorporated into DNA and which could be a trigger to induce cell death. The binding and subsequent cell death events would be absent in colorectal tumors with MSI-H, which have lost intact DNA mismatch repair function. These findings suggest that: (a) tumor cytotoxicity of 5-FU is mediated by DNA mechanisms in addition to well-known RNA mechanisms, and (b) patients whose tumors demonstrate MSI-H may not benefit from 5-FU therapy. Future studies should include a better understanding of the cellular mechanisms of the DNA recognition of 5-FU, multi-centered prospective trials investigating the survival benefit of 5-FU based on genomic instability, and the investigation of alternative chemotherapeutic regimens for patients with MSI-H tumors to improve survival.
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Affiliation(s)
- Won-Seok Jo
- Department of Medicine, University of California, San Diego, CA, USA
| | - John M. Carethers
- Department of Medicine, University of California, San Diego, CA, USA
- Rebecca and John Moores Comprehensive Cancer Center, University of California, San Diego, CA, USA
- VA San Diego Healthcare System, San Diego, CA, USA
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