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TAGAYA AKIRA. A general model for symmetry and asymmetry of nonmetric traits and congenital anomalies and tumors: reviving the proposals sacrificed to false myths. ANTHROPOL SCI 2022. [DOI: 10.1537/ase.210814] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022]
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Hülsenbeck I, Frank M, Biewald E, Kanber D, Lohmann DR, Ketteler P. Introduction of a Variant Classification System for Analysis of Genotype-Phenotype Relationships in Heritable Retinoblastoma. Cancers (Basel) 2021; 13:cancers13071605. [PMID: 33807189 PMCID: PMC8037437 DOI: 10.3390/cancers13071605] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2021] [Revised: 03/26/2021] [Accepted: 03/28/2021] [Indexed: 11/22/2022] Open
Abstract
Simple Summary Heritable retinoblastoma is a genetic disease that predisposes to develop multiple retinoblastomas in childhood and other extraocular tumors later in life. It is caused by genetic variants in the RB1 gene. Here we present a new classification for genetic variants in the RB1 gene (REC) that focuses on the variant’s effect. The different classes, REC-I to -V, correlate with different risks of tumor predisposition. REC correlated with different clinical courses when applied in our study cohort. REC aims to facilitate risk estimation for physicians, patients and their families, and researchers and to improve the definition of the necessity of screening examination. Abstract Constitutional haploinsufficiency of the RB1 gene causes heritable retinoblastoma, a tumor predisposition syndrome. Patients with heritable retinoblastoma develop multiple retinoblastomas early in childhood and other extraocular tumors later in life. Constitutional pathogenic variants in RB1 are heterogeneous, and a few genotype-phenotype correlations have been described. To identify further genotype-phenotype relationships, we developed the retinoblastoma variant effect classification (REC), which considers each variant’s predicted effects on the common causal mediator, RB1 protein pRB. For validation, the RB1 variants of 287 patients were grouped according to REC. Multiple aspects of phenotypic expression were analyzed, known genotype-phenotype associations were revised, and new relationships were explored. Phenotypic expression of patients with REC-I, -II, and -III was distinct. Remarkably, the phenotype of patients with variants causing residual amounts of truncated pRB (REC-I) was more severe than patients with complete loss of RB1 (REC-II). The age of diagnosis of REC-I variants appeared to be distinct depending on truncation’s localization relative to pRB structure domains. REC classes identify genotype-phenotype relationships and, therefore, this classification framework may serve as a tool to develop tailored tumor screening programs depending on the type of RB1 variant.
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Affiliation(s)
- Isabel Hülsenbeck
- Department of Pediatric Hematology and Oncology, University Duisburg-Essen, University Hospital Essen, Hufelandstrasse 55, 45122 Essen, Germany;
- Eye Oncogenetics Research Group, University Hospital Essen, 45122 Essen, Germany; (D.K.); (D.R.L.)
| | - Mirjam Frank
- Institute for Medical Informatics, Biometry and Epidemiology, University Duisburg-Essen, University Hospital Essen, 45122 Essen, Germany;
| | - Eva Biewald
- Department of Ophthalmology, University Duisburg-Essen, University Hospital Essen, 45122 Essen, Germany;
| | - Deniz Kanber
- Eye Oncogenetics Research Group, University Hospital Essen, 45122 Essen, Germany; (D.K.); (D.R.L.)
- Institute of Human Genetics, University Duisburg-Essen, 45122 Essen, Germany
| | - Dietmar R. Lohmann
- Eye Oncogenetics Research Group, University Hospital Essen, 45122 Essen, Germany; (D.K.); (D.R.L.)
- Institute of Human Genetics, University Duisburg-Essen, 45122 Essen, Germany
- German Cancer Consortium (DKTK), Partner Site Essen/Düsseldorf, 69120 Heidelberg, Germany
| | - Petra Ketteler
- Department of Pediatric Hematology and Oncology, University Duisburg-Essen, University Hospital Essen, Hufelandstrasse 55, 45122 Essen, Germany;
- Eye Oncogenetics Research Group, University Hospital Essen, 45122 Essen, Germany; (D.K.); (D.R.L.)
- Institute of Human Genetics, University Duisburg-Essen, 45122 Essen, Germany
- German Cancer Consortium (DKTK), Partner Site Essen/Düsseldorf, 69120 Heidelberg, Germany
- Correspondence:
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Rodríguez-Martín C, Robledo C, Gómez-Mariano G, Monzón S, Sastre A, Abelairas J, Sábado C, Martín-Begué N, Ferreres JC, Fernández-Teijeiro A, González-Campora R, Rios-Moreno MJ, Zaballos Á, Cuesta I, Martínez-Delgado B, Posada M, Alonso J. Frequency of low-level and high-level mosaicism in sporadic retinoblastoma: genotype-phenotype relationships. J Hum Genet 2019; 65:165-174. [PMID: 31772335 DOI: 10.1038/s10038-019-0696-z] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2019] [Revised: 11/13/2019] [Accepted: 11/14/2019] [Indexed: 11/10/2022]
Abstract
Somatic mutational mosaicism is a common feature of monogenic genetic disorders, particularly in diseases such as retinoblastoma, with high rates of de novo mutations. The detection and quantification of mosaicism is particularly relevant in these diseases, since it has important implications for genetic counseling, patient management, and probably also on disease onset and progression. In order to assess the rate of somatic mosaicism (high- and low-level mosaicism) in sporadic retinoblastoma patients, we analyzed a cohort of 153 patients with sporadic retinoblastoma using ultra deep next-generation sequencing. High-level mosaicism was detected in 14 out of 100 (14%) bilateral patients and in 11 out of 29 (38%) unilateral patients in whom conventional Sanger sequencing identified a pathogenic mutation in blood DNA. In addition, low-level mosaicism was detected in 3 out of 16 (19%) unilateral patients in whom conventional screening was negative in blood DNA. Our results also reveal that mosaicism was associated to delayed retinoblastoma onset particularly in unilateral patients. Finally we compared the level of mosaicism in different tissues to identify the best DNA source to identify mosaicism in retinoblastoma patients. In light of these results we recommended analyzing the mosaic status in all retinoblastoma patients using accurate techniques such as next-generation sequencing, even in those cases in which conventional Sanger sequencing identified a pathogenic mutation in blood DNA. Our results suggest that a significant proportion of those cases are truly mosaics that could have been overlooked. This information should be taking into consideration in the management and genetic counseling of retinoblastoma patients and families.
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Affiliation(s)
- Carlos Rodríguez-Martín
- Unidad de Tumores Sólidos Infantiles, Instituto de Investigación de Enfermedades Raras, Instituto de Salud Carlos III, Majadahonda, Madrid, Spain
| | - Cristina Robledo
- Unidad de Tumores Sólidos Infantiles, Instituto de Investigación de Enfermedades Raras, Instituto de Salud Carlos III, Majadahonda, Madrid, Spain
| | - Gema Gómez-Mariano
- Instituto de Investigación de Enfermedades Raras, Instituto de Salud Carlos III, Majadahonda, Madrid, Spain
| | - Sara Monzón
- Bioinformatics Unit, Core Scientific and Technical Units, Instituto de Salud Carlos III, Majadahonda, Madrid, Spain
| | - Ana Sastre
- University Hospital La Paz, Madrid, Spain
| | | | - Constantino Sábado
- Pediatric Oncohematology Deparment, Vall d'Hebron Hospital, Barcelona, Spain
| | - Nieves Martín-Begué
- Pediatric Ophthalmology Department, Vall d'Hebron Hospital, Barcelona, Spain
| | - Joan Carles Ferreres
- Parc Taulí Hospital Universitari. Institut d'Investigació i Innovació Parc Taulí I3PT, Universitat Autònoma de Barcelona, Sabadell, Spain
| | | | | | - María José Rios-Moreno
- Department of Anatomic Pathology, Hospital Universitario Virgen Macarena, Sevilla, Spain
| | - Ángel Zaballos
- Genomics Unit, Core Scientific and Technical Units, Instituto de Salud Carlos III, Majadahonda, Madrid, Spain
| | - Isabel Cuesta
- Bioinformatics Unit, Core Scientific and Technical Units, Instituto de Salud Carlos III, Majadahonda, Madrid, Spain
| | - Beatriz Martínez-Delgado
- Instituto de Investigación de Enfermedades Raras, Instituto de Salud Carlos III, Majadahonda, Madrid, Spain.,Centro de Investigación Biomédica en Red de Enfermedades Raras, Instituto de Salud Carlos III (CB06/07/1009; CIBERER-ISCIII), Majadahonda, Madrid, Spain
| | - Manuel Posada
- Instituto de Investigación de Enfermedades Raras, Instituto de Salud Carlos III, Majadahonda, Madrid, Spain.,Centro de Investigación Biomédica en Red de Enfermedades Raras, Instituto de Salud Carlos III (CB06/07/1009; CIBERER-ISCIII), Majadahonda, Madrid, Spain
| | - Javier Alonso
- Unidad de Tumores Sólidos Infantiles, Instituto de Investigación de Enfermedades Raras, Instituto de Salud Carlos III, Majadahonda, Madrid, Spain. .,Centro de Investigación Biomédica en Red de Enfermedades Raras, Instituto de Salud Carlos III (CB06/07/1009; CIBERER-ISCIII), Majadahonda, Madrid, Spain.
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Imperatore V, Pinto AM, Gelli E, Trevisson E, Morbidoni V, Frullanti E, Hadjistilianou T, De Francesco S, Toti P, Gusson E, Roversi G, Accogli A, Capra V, Mencarelli MA, Renieri A, Ariani F. Parent-of-origin effect of hypomorphic pathogenic variants and somatic mosaicism impact on phenotypic expression of retinoblastoma. Eur J Hum Genet 2018; 26:1026-1037. [PMID: 29662154 DOI: 10.1038/s41431-017-0054-6] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2017] [Revised: 10/27/2017] [Accepted: 11/23/2017] [Indexed: 11/09/2022] Open
Abstract
Retinoblastoma is the most common eye cancer in children. Numerous families have been described displaying reduced penetrance and expressivity. An extensive molecular characterization of seven families led us to characterize the two main mechanisms impacting on phenotypic expression, as follows: (i) mosaicism of amorphic pathogenic variants; and (ii) parent-of-origin-effect of hypomorphic pathogenic variants. Somatic mosaicism for RB1 splicing variants (c.1960+5G>C and c.2106+2T>C), leading to a complete loss of function was demonstrated by high-depth NGS in two families. In both cases, the healthy carrier parent (one with retinoma) showed a variant frequency lower than that expected for a heterozygous individual, indicating a 56-60% mosaicism level. Previous evidences of a ~3-fold excess of RB1 maternal canonical transcript led us to hypothesize that this differential allelic expression could influence phenotypic outcome in families at risk for RB onset. Accordingly, in five families, we identified a higher tumor risk associated with paternally inherited hypomorphic pathogenic variants, namely a deletion resulting in the loss of 37 amino acids at the N-terminus (c.608-16_608del), an exonic substitution with a "leaky" splicing effect (c.1331A>G), a partially deleterious substitution (c.1981C>T) and a truncating C-terminal variant (c.2663+2T>C). The identification of these mechanisms changes the genetic/prenatal counseling and the clinical management of families, indicating a higher recurrence risk when the hypomorphic pathogenic variant is inherited from the father, and suggesting the need for second tumor surveillance in unaffected carriers at risk of developing adult-onset cancer such as osteosarcoma or leiomyosarcoma.
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Affiliation(s)
| | - Anna Maria Pinto
- Medical Genetics, University of Siena, Siena, Italy.,Genetica Medica, Azienda Ospedaliera Universitaria Senese, Siena, Italy
| | - Elisa Gelli
- Medical Genetics, University of Siena, Siena, Italy
| | - Eva Trevisson
- Department of Woman and Child Health, University of Padova Istituto di Ricerca Pediatrica, IRP, Città della Speranza, Padova, Italy.,Istituto di Ricerca Pediatrica, IRP, Città della Speranza, Padova, Italy
| | - Valeria Morbidoni
- Department of Woman and Child Health, University of Padova Istituto di Ricerca Pediatrica, IRP, Città della Speranza, Padova, Italy.,Istituto di Ricerca Pediatrica, IRP, Città della Speranza, Padova, Italy
| | | | - Theodora Hadjistilianou
- Unit of Ophthalmology and Retinoblastoma Referral Center, Department of Surgery, University of Siena, Policlinico 'Santa Maria alle Scotte', Siena, Italy
| | - Sonia De Francesco
- Unit of Ophthalmology and Retinoblastoma Referral Center, Department of Surgery, University of Siena, Policlinico 'Santa Maria alle Scotte', Siena, Italy
| | - Paolo Toti
- Department of Medical Biotechnology, Section of Pathology, University of Siena, Policlinico 'Santa Maria alle Scotte', Siena, Italy
| | - Elena Gusson
- Unit of Ophthalmology, Azienda Ospedaliera Universitaria Integrata, Verona, Italy
| | - Gaia Roversi
- Department of Medicine and Surgery, University Milan-Bicocca; Ospedale San Gerardo, ASST Monza, Monza, Italy
| | | | | | - Maria Antonietta Mencarelli
- Medical Genetics, University of Siena, Siena, Italy.,Genetica Medica, Azienda Ospedaliera Universitaria Senese, Siena, Italy
| | - Alessandra Renieri
- Medical Genetics, University of Siena, Siena, Italy. .,Genetica Medica, Azienda Ospedaliera Universitaria Senese, Siena, Italy.
| | - Francesca Ariani
- Medical Genetics, University of Siena, Siena, Italy.,Genetica Medica, Azienda Ospedaliera Universitaria Senese, Siena, Italy
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Wang M, Liu Y, Fang W, Liu K, Jiao X, Wang Z, Wang J, Zang YS. Increased SNAT1 is a marker of human osteosarcoma and potential therapeutic target. Oncotarget 2017; 8:78930-78939. [PMID: 29108276 PMCID: PMC5668009 DOI: 10.18632/oncotarget.20693] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2017] [Accepted: 05/22/2017] [Indexed: 11/25/2022] Open
Abstract
Background SLC38A1/SNAT1 has been found to play an essential role in human development, but its role in osteosarcoma (OS) has yet to be evaluated. The purpose of this study was to assess the expression of SLC38A1/SNAT1 in patients with OS, and further investigate the mechanisms by which it affects tumor growth and metastasis. Methods Tissue microarray blocks and immunohistochemical studies were carried out to assess the expression of SNAT1 in 165 OS specimens. Its correlation with clinicopathological characteristics was then analyzed. The function of SNAT1 in OS cells was investigated by silencing SNAT1 using SNAT1-shRNA in vitro and in vivo. Results SNAT1 was highly expressed in 85% OS and significantly closely associated with pulmonary metastasis. Patients with high SNAT1 expression survived for shorter periods than those with low SNAT1 expression. Suppression of endogenous SNAT1 led to inhibition of cell proliferation, cell colony formation, and cell migration in vitro, and retarded tumor growth in xenograft models. Silencing SNAT1 reduced expression of MMP9, vimentin, fibronectin, p-Akt, p-mTOR, and VEGF. Conclusions Our results indicated that increased expression of SNAT1 is a common event in OS. SNAT1 played an essential role in the development and progression of osteosarcoma, which may serve as a prognostic and therapeutic marker of OS.
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Affiliation(s)
- Miaomiao Wang
- Department of Medical Oncology, Changzheng Hospital, Shanghai 200070, China
| | - Ying Liu
- Department of Medical Oncology, Changzheng Hospital, Shanghai 200070, China
| | - Wenzheng Fang
- Department of Medical Oncology, Changzheng Hospital, Shanghai 200070, China
| | - Ke Liu
- Department of Medical Oncology, Changzheng Hospital, Shanghai 200070, China
| | - Xiaodong Jiao
- Department of Medical Oncology, Changzheng Hospital, Shanghai 200070, China
| | - Zhan Wang
- Department of Medical Oncology, Changzheng Hospital, Shanghai 200070, China
| | - Jiejun Wang
- Department of Medical Oncology, Changzheng Hospital, Shanghai 200070, China
| | - Yuan-Sheng Zang
- Department of Medical Oncology, Changzheng Hospital, Shanghai 200070, China
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Soliman SE, Racher H, Zhang C, MacDonald H, Gallie BL. Genetics and Molecular Diagnostics in Retinoblastoma--An Update. Asia Pac J Ophthalmol (Phila) 2017; 6:197-207. [PMID: 28399338 DOI: 10.22608/apo.201711] [Citation(s) in RCA: 56] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2017] [Accepted: 03/09/2017] [Indexed: 11/08/2022] Open
Abstract
Retinoblastoma is the prototype genetic cancer: in one or both eyes of young children, most retinoblastomas are initiated by biallelic mutation of the retinoblastoma tumor suppressor gene, RB1, in a developing retinal cell. All those with bilateral retinoblastoma have heritable cancer, although 95% have not inherited the RB1 mutation. Non-heritable retinoblastoma is always unilateral, with 98% caused by loss of both RB1 alleles from the tumor, whereas 2% have normal RB1 in tumors initiated by amplification of the MYCN oncogene. Good understanding of retinoblastoma genetics supports optimal care for retinoblastoma children and their families. Retinoblastoma is the first cancer to officially acknowledge the seminal role of genetics in cancer, by incorporating "H" into the eighth edition of cancer staging (2017): those who carry the RB1 cancer-predisposing gene are H1; those proven to not carry the familial RB1 mutation are H0; and those at unknown risk are HX. We suggest H0* be used for those with residual <1% risk to carry a RB1 mutation due to undetectable mosaicism. Loss of RB1 from a susceptible developing retinal cell initiates the benign precursor, retinoma. Progressive genomic changes result in retinoblastoma, and cancer progression ensues with increasing genomic disarray. Looking forward, novel therapies are anticipated from studies of retinoblastoma and metastatic tumor cells and the second primary cancers that the carriers of RB1 mutations are at high risk to develop. Here, we summarize the concepts of retinoblastoma genetics for ophthalmologists in a question/answer format to assist in the care of patients and their families.
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Affiliation(s)
- Sameh E Soliman
- Department of Ophthalmology and Vision Sciences, University of Toronto, Ontario, Canada
- Department of Ophthalmology, Faculty of Medicine, University of Alexandria, Alexandria, Egypt
| | | | - Chengyue Zhang
- Department of Ophthalmology, Beijing Children's Hospital, Capital Medical University, Beijing, China
| | - Heather MacDonald
- Department of Ophthalmology and Vision Sciences, University of Toronto, Ontario, Canada
| | - Brenda L Gallie
- Department of Ophthalmology and Vision Sciences, University of Toronto, Ontario, Canada
- Departments of Ophthalmology, Molecular Genetics, and Medical Biophysics, University of Toronto, Toronto, Canada
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Ishak CA, Marshall AE, Passos DT, White CR, Kim SJ, Cecchini MJ, Ferwati S, MacDonald WA, Howlett CJ, Welch ID, Rubin SM, Mann MRW, Dick FA. An RB-EZH2 Complex Mediates Silencing of Repetitive DNA Sequences. Mol Cell 2016; 64:1074-1087. [PMID: 27889452 DOI: 10.1016/j.molcel.2016.10.021] [Citation(s) in RCA: 116] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2016] [Revised: 08/17/2016] [Accepted: 10/17/2016] [Indexed: 12/21/2022]
Abstract
Repetitive genomic regions include tandem sequence repeats and interspersed repeats, such as endogenous retroviruses and LINE-1 elements. Repressive heterochromatin domains silence expression of these sequences through mechanisms that remain poorly understood. Here, we present evidence that the retinoblastoma protein (pRB) utilizes a cell-cycle-independent interaction with E2F1 to recruit enhancer of zeste homolog 2 (EZH2) to diverse repeat sequences. These include simple repeats, satellites, LINEs, and endogenous retroviruses as well as transposon fragments. We generated a mutant mouse strain carrying an F832A mutation in Rb1 that is defective for recruitment to repetitive sequences. Loss of pRB-EZH2 complexes from repeats disperses H3K27me3 from these genomic locations and permits repeat expression. Consistent with maintenance of H3K27me3 at the Hox clusters, these mice are developmentally normal. However, susceptibility to lymphoma suggests that pRB-EZH2 recruitment to repetitive elements may be cancer relevant.
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Affiliation(s)
- Charles A Ishak
- London Regional Cancer Program, London, ON N6A 4L6, Canada; Department of Biochemistry, Western University, London, ON N6A 3K7, Canada
| | - Aren E Marshall
- London Regional Cancer Program, London, ON N6A 4L6, Canada; Department of Biochemistry, Western University, London, ON N6A 3K7, Canada
| | - Daniel T Passos
- London Regional Cancer Program, London, ON N6A 4L6, Canada; Department of Biochemistry, Western University, London, ON N6A 3K7, Canada
| | - Carlee R White
- Children's Health Research Institute, London, ON N6A 4L6, Canada; Department of Biochemistry, Western University, London, ON N6A 3K7, Canada
| | - Seung J Kim
- London Regional Cancer Program, London, ON N6A 4L6, Canada; Department of Biochemistry, Western University, London, ON N6A 3K7, Canada
| | - Matthew J Cecchini
- London Regional Cancer Program, London, ON N6A 4L6, Canada; Department of Pathology and Laboratory Medicine, Western University, London, ON N6A 3K7, Canada
| | - Sara Ferwati
- London Regional Cancer Program, London, ON N6A 4L6, Canada; Department of Biochemistry, Western University, London, ON N6A 3K7, Canada
| | - William A MacDonald
- Magee-Womens Research Institute, Pittsburgh, PA 15213, USA; Department of Obstetrics, Gynecology, and Reproductive Sciences, University of Pittsburgh, Pittsburgh, PA 15260, USA
| | - Christopher J Howlett
- Department of Pathology and Laboratory Medicine, Western University, London, ON N6A 3K7, Canada
| | - Ian D Welch
- Animal Care Services, University of British Columbia, Vancouver, BC V6T1Z4, Canada
| | - Seth M Rubin
- Department of Chemistry and Biochemistry, University of California, Santa Cruz, Santa Cruz, CA 95064, USA
| | - Mellissa R W Mann
- Magee-Womens Research Institute, Pittsburgh, PA 15213, USA; Department of Obstetrics, Gynecology, and Reproductive Sciences, University of Pittsburgh, Pittsburgh, PA 15260, USA
| | - Frederick A Dick
- London Regional Cancer Program, London, ON N6A 4L6, Canada; Children's Health Research Institute, London, ON N6A 4L6, Canada; Department of Biochemistry, Western University, London, ON N6A 3K7, Canada.
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APC/C and retinoblastoma interaction: cross-talk of retinoblastoma protein with the ubiquitin proteasome pathway. Biosci Rep 2016; 36:BSR20160152. [PMID: 27402801 PMCID: PMC5025812 DOI: 10.1042/bsr20160152] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2016] [Accepted: 07/08/2016] [Indexed: 12/15/2022] Open
Abstract
The ubiquitin (Ub) ligase anaphase promoting complex/cyclosome (APC/C) and the tumour suppressor retinoblastoma protein (pRB) play key roles in cell cycle regulation. APC/C is a critical regulator of mitosis and G1-phase of the cell cycle whereas pRB keeps a check on proliferation by inhibiting transition to the S-phase. APC/C and pRB interact with each other via the co-activator of APC/C, FZR1, providing an alternative pathway of regulation of G1 to S transition by pRB using a post-translational mechanism. Both pRB and FZR1 have complex roles and are implicated not only in regulation of cell proliferation but also in differentiation, quiescence, apoptosis, maintenance of chromosomal integrity and metabolism. Both are also targeted by transforming viruses. We discuss recent advances in our understanding of the involvement of APC/C and pRB in cell cycle based decisions and how these insights will be useful for development of anti-cancer and anti-viral drugs.
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Cheng YH, Streicher DA, Waning DL, Chitteti BR, Gerard-O'Riley R, Horowitz MC, Bidwell JP, Pavalko FM, Srour EF, Mayo LD, Kacena MA. Signaling pathways involved in megakaryocyte-mediated proliferation of osteoblast lineage cells. J Cell Physiol 2015; 230:578-86. [PMID: 25160801 DOI: 10.1002/jcp.24774] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2014] [Accepted: 08/22/2014] [Indexed: 01/07/2023]
Abstract
Recent studies suggest that megakaryocytes (MKs) may play a significant role in skeletal homeostasis, as evident by the occurrence of osteosclerosis in multiple MK related diseases (Lennert et al., 1975; Thiele et al., 1999; Chagraoui et al., 2006). We previously reported a novel interaction whereby MKs enhanced proliferation of osteoblast lineage/osteoprogenitor cells (OBs) by a mechanism requiring direct cell-cell contact. However, the signal transduction pathways and the downstream effector molecules involved in this process have not been characterized. Here we show that MKs contact with OBs, via beta1 integrin, activate the p38/MAPKAPK2/p90RSK kinase cascade in the bone cells, which causes Mdm2 to neutralizes p53/Rb-mediated check point and allows progression through the G1/S. Interestingly, activation of MAPK (ERK1/2) and AKT, collateral pathways that regulate the cell cycle, remained unchanged with MK stimulation of OBs. The MK-to-OB signaling ultimately results in significant increases in the expression of c-fos and cyclin A, necessary for sustaining the OB proliferation. Overall, our findings show that OBs respond to the presence of MKs, in part, via an integrin-mediated signaling mechanism, activating a novel response axis that de-represses cell cycle activity. Understanding the mechanisms by which MKs enhance OB proliferation will facilitate the development of novel anabolic therapies to treat bone loss associated with osteoporosis and other bone-related diseases.
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Affiliation(s)
- Ying-Hua Cheng
- Department of Orthopaedic Surgery, Indiana University School of Medicine, Indianapolis, Indiana
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10
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Popov B, Petrov N. pRb-E2F signaling in life of mesenchymal stem cells: Cell cycle, cell fate, and cell differentiation. Genes Dis 2014; 1:174-187. [PMID: 30258863 PMCID: PMC6150080 DOI: 10.1016/j.gendis.2014.09.007] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2014] [Accepted: 09/14/2014] [Indexed: 02/07/2023] Open
Abstract
Mesenchymal stem cells (MSCs) are multipotent cells that can differentiate into various mesodermal lines forming fat, muscle, bone, and other lineages of connective tissue. MSCs possess plasticity and under special metabolic conditions may transform into cells of unusual phenotypes originating from ecto- and endoderm. After transplantation, MSCs release the humoral factors promoting regeneration of the damaged tissue. During last five years, the numbers of registered clinical trials of MSCs have increased about 10 folds. This gives evidence that MSCs present a new promising resource for cell therapy of the most dangerous diseases. The efficacy of the MSCs therapy is limited by low possibilities to regulate their conversion into cells of damaged tissues that is implemented by the pRb-E2F signaling. The widely accepted viewpoint addresses pRb as ubiquitous regulator of cell cycle and tumor suppressor. However, current publications suggest that basic function of the pRb-E2F signaling in development is to regulate cell fate and differentiation. Through facultative and constitutive chromatin modifications, pRb-E2F signaling promotes transient and stable cells quiescence, cell fate choice to differentiate, to senesce, or to die. Loss of pRb is associated with cancer cell fate. pRb regulates cell fate by retaining quiescence of one cell population in favor of commitment of another or by suppression of genes of different cell phenotype. pRb is the founder member of the "pocket protein" family possessing functional redundancy. Critical increase in the efficacy of the MSCs based cell therapy will depend on precise understanding of various aspects of the pRb-E2F signaling.
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Affiliation(s)
- Boris Popov
- Institute of Cytology, Russian Academy of Sciences, St.Petersburg, 4, Tikhoretsky Av., 194064, Russia
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12
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Cooper DN, Krawczak M, Polychronakos C, Tyler-Smith C, Kehrer-Sawatzki H. Where genotype is not predictive of phenotype: towards an understanding of the molecular basis of reduced penetrance in human inherited disease. Hum Genet 2013; 132:1077-130. [PMID: 23820649 PMCID: PMC3778950 DOI: 10.1007/s00439-013-1331-2] [Citation(s) in RCA: 417] [Impact Index Per Article: 37.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2013] [Accepted: 06/15/2013] [Indexed: 02/06/2023]
Abstract
Some individuals with a particular disease-causing mutation or genotype fail to express most if not all features of the disease in question, a phenomenon that is known as 'reduced (or incomplete) penetrance'. Reduced penetrance is not uncommon; indeed, there are many known examples of 'disease-causing mutations' that fail to cause disease in at least a proportion of the individuals who carry them. Reduced penetrance may therefore explain not only why genetic diseases are occasionally transmitted through unaffected parents, but also why healthy individuals can harbour quite large numbers of potentially disadvantageous variants in their genomes without suffering any obvious ill effects. Reduced penetrance can be a function of the specific mutation(s) involved or of allele dosage. It may also result from differential allelic expression, copy number variation or the modulating influence of additional genetic variants in cis or in trans. The penetrance of some pathogenic genotypes is known to be age- and/or sex-dependent. Variable penetrance may also reflect the action of unlinked modifier genes, epigenetic changes or environmental factors. At least in some cases, complete penetrance appears to require the presence of one or more genetic variants at other loci. In this review, we summarize the evidence for reduced penetrance being a widespread phenomenon in human genetics and explore some of the molecular mechanisms that may help to explain this enigmatic characteristic of human inherited disease.
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Affiliation(s)
- David N. Cooper
- Institute of Medical Genetics, School of Medicine, Cardiff University, Heath Park, Cardiff, CF14 4XN UK
| | - Michael Krawczak
- Institute of Medical Informatics and Statistics, Christian-Albrechts University, 24105 Kiel, Germany
| | | | - Chris Tyler-Smith
- The Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge, CB10 1SA UK
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Ahani A, Akbari MT, Saliminejad K, Behnam B, Akhondi MM, Vosoogh P, Ghassemi F, Naseripour M, Bahoush G, Khorshid HRK. Screening for large rearrangements of the RB1 gene in Iranian patients with retinoblastoma using multiplex ligation-dependent probe amplification. Mol Vis 2013; 19:454-62. [PMID: 23441118 PMCID: PMC3580967] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2012] [Accepted: 02/20/2013] [Indexed: 11/25/2022] Open
Abstract
PURPOSE To screen deletions/duplications of the RB1 gene in a large cohort of Iranian patients using the multiplex ligation-dependent probe amplification (MLPA) technique. METHODS A total of 121 patients with retinoblastoma, involving 55 unilateral and 66 bilateral or familial retinoblastomas, were included in this study. Among these patients, 121 blood and 43 tissue samples were available. DNA was extracted from the blood and tissue samples and analyzed with an RB1-specific MLPA probe set. The mutation findings were validated with SYBR Green Real-Time PCR. RESULTS Twenty-two mutations were found in 21 patients; of these, ten mutations were detected in patients with isolated unilateral retinoblastoma. CONCLUSIONS Our results suggested that MLPA is a fast, reliable, and powerful method for detecting deletions/duplications in patients with retinoblastoma.
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Affiliation(s)
- Ali Ahani
- Reproductive Biotechnology Research Center, Avicenna Research Institute, ACECR, Tehran, Iran,Department of Medical Genetics, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, Iran
| | - Mohammad Taghi Akbari
- Department of Medical Genetics, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, Iran
| | - Kioomars Saliminejad
- Reproductive Biotechnology Research Center, Avicenna Research Institute, ACECR, Tehran, Iran
| | - Babak Behnam
- Department of Genetics and Molecular Biology, Tehran University of Medical Sciences, Tehran, Iran
| | - Mohammad Mehdi Akhondi
- Reproductive Biotechnology Research Center, Avicenna Research Institute, ACECR, Tehran, Iran
| | | | - Farriba Ghassemi
- Eye Research Center, Farabi Hospital, Tehran University of Medical Sciences
| | - Masood Naseripour
- Eye Research Center, Rasoul Akram Hospital, Tehran University of Medical Sciences
| | - Gholamreza Bahoush
- Oncopathology Research Center, Ali-Asghar Children Hospital, Tehran University of Medical Sciences
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14
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Rb1/105 gene alterations and head and neck carcinogenesis. Mol Biol Rep 2012; 39:9573-81. [PMID: 22744425 DOI: 10.1007/s11033-012-1822-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2011] [Accepted: 06/10/2012] [Indexed: 10/28/2022]
Abstract
Retinoblastoma gene (Rb1) is a tumor suppressor gene, which plays a pivotal role in cell cycle regulation, promoting G1/S arrest and growth restriction through inhibition of the E2F transcription factor. Abnormalities in the genes involved in cell cycle, including Rb1, have been reported in head and neck cancer (HNC) patients. Studies regarding Rb1 have been observed in different world populations but data is missing for Pakistani population. This study was aimed to analyze the genetic aberrations of Rb1 and their association with the development of HNC in Pakistani population. Genomic DNA was isolated from blood samples of 300 HNC patients and 270 controls. Salient coding region of gene was amplified by using Polymerase Chain Reaction (PCR). PCR conditions were optimized for each exon separately. Amplified products were analyzed for mutational screening using Single strand confirmation polymorphism (SSCP) technique followed by sequence analysis. Sequence analysis revealed five missense mutations g77082G>C, g77083G>A, g170220A>T, g170221G>C, g170228T>A, two frameshift mutations, two stop codon and two intronic substitutions in this study. The overall frequency of these mutations was 0.71. Frequency of nonsense mutations; Lys462stop (Novel) and Ser834stop (CM952105) were 0.15 and 0.14 respectively. We also report here novel missense mutations, frameshift mutation and a stop codon Lys462stop in HNC patients of Pakistani origin.This study suggests that the Rb1 germline mutations may contribute to genetic susceptibility for HNC. To our knowledge, this is the first report that Rb1 gene may be associated with risk of cancer in Pakistani population.
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Hung CC, Lin SY, Lee CN, Chen CP, Lin SP, Chao MC, Chiou SS, Su YN. Low penetrance of retinoblastoma for p.V654L mutation of the RB1 gene. BMC MEDICAL GENETICS 2011; 12:76. [PMID: 21615945 PMCID: PMC3119181 DOI: 10.1186/1471-2350-12-76] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/29/2010] [Accepted: 05/26/2011] [Indexed: 02/07/2023]
Abstract
Background Retinoblastoma is caused by compound heterozygosity or homozygosity of retinoblastoma gene (RB1) mutations. In germline retinoblastoma, mutations in the RB1 gene predispose individuals to increased cancer risks during development. These mutations segregate as autosomal dominant traits with high penetrance (90%). Methods We screened 30 family members from one family using high resolution melting assay and DNA direct sequencing for mutations in the RB1 gene. We evaluate the phenotype and penetrance of germline mutations of the RB1 gene in a large Taiwanese family. Results The molecular analysis and clinical details of this family showed phenotypic variability associated with the p.V654L mutation in exon 19 of the RB1 gene in 11 family members. The phenotype varied from asymptomatic to presence of a unilateral tumor. Only four individuals (2 males and 2 females) developed unilateral retinoblastoma, which resulted in calculated low penetrance of 36% (4/11). The four individuals with retinoblastoma were diagnosed before the age of three years. None of their relatives exhibited variable severity or bilateral retinoblastoma. Conclusions The diseased-eye ratio for this family was 0.36, which is lower than current estimates. This suggests that the RB1 p.V654L mutation is a typical mutation associated with low penetrance.
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Affiliation(s)
- Chia-Cheng Hung
- Graduate Institute of Clinical Genomics, National Taiwan University College of Medicine, Taipei, Taiwan
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16
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Pickard A, Wong PP, McCance DJ. Acetylation of Rb by PCAF is required for nuclear localization and keratinocyte differentiation. J Cell Sci 2010; 123:3718-26. [PMID: 20940255 DOI: 10.1242/jcs.068924] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Although the retinoblastoma protein (Rb) functions as a checkpoint in the cell cycle, it also regulates differentiation. It has recently been shown that Rb is acetylated during differentiation; however, the role of this modification has not been identified. Depletion of Rb levels with short hairpin RNA resulted in inhibition of human keratinocyte differentiation, delayed cell cycle exit and allowed cell cycle re-entry. Restoration of Rb levels rescued defects in differentiation and cell cycle exit and re-entry; however, re-expression of Rb with the major acetylation sites mutated did not. During keratinocyte differentiation, acetylation of Rb is mediated by PCAF and it is further shown that PCAF acetyltransferase activity is also required for normal differentiation. The major acetylation sites in Rb are located within the nuclear localization sequence and, although mutation did not alter Rb localization in cycling cells, the mutant is mislocalized to the cytoplasm during differentiation. Studies indicate that acetylation is a mechanism for controlling Rb localization in human keratinocytes, with either reduction of the PCAF or exogenous expression of the deacetylase SIRT1, resulting in mislocalization of Rb. These findings identify PCAF-mediated acetylation of Rb as an event required to retain Rb within the nucleus during keratinocyte differentiation.
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Affiliation(s)
- Adam Pickard
- Centre for Cancer Research and Cell Biology, Queen's University Belfast, Belfast, BT9 7BL, UK
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17
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Kuiper RP, Ligtenberg MJL, Hoogerbrugge N, Geurts van Kessel A. Germline copy number variation and cancer risk. Curr Opin Genet Dev 2010; 20:282-9. [PMID: 20381334 DOI: 10.1016/j.gde.2010.03.005] [Citation(s) in RCA: 92] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2010] [Revised: 03/05/2010] [Accepted: 03/15/2010] [Indexed: 01/13/2023]
Abstract
The human genome is subject to substantial structural variation, including copy number variation (CNV). Constitutional CNVs may either represent benign polymorphic variants or be associated with disease, including cancer predisposition. Rare nonpolymorphic CNVs, that is DNA lesions that result in gene deletions, inversions, and/or fusions, may be responsible for a high cancer risk. In addition, we previously elucidated a mechanism by which CNV-based transcriptional read-through mediates inactivation of a neighboring gene through in cis hypermethylation of its promoter. This novel mechanism explains the etiology of a recurrent and strongly inherited tissue-restricted epimutation. Recently, we obtained supporting evidence for such a CNV-associated scenario, suggesting that it may be more prevalent than previously thought. We expect that copy number profiling in unexplained high-risk families will lead to the discovery of additional cancer-predisposing genes and/or mechanisms.
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Affiliation(s)
- Roland P Kuiper
- Department of Human Genetics, Radboud University Nijmegen Medical Centre, Nijmegen Centre for Molecular Life Sciences, Nijmegen, The Netherlands.
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Abstract
PURPOSE OF REVIEW DNA copy number variations (CNVs) comprise a recently discovered element of genetic variation that affects a greater cumulative fraction of the genome than single-nucleotide polymorphisms (SNPs). This review discusses current understanding of the characteristics of CNVs in the human genome and explores the emerging discoveries of both constitutional and somatic CNVs in an ever-expanding variety of human cancers. RECENT FINDINGS The advent of high-resolution SNP arrays has made it possible to identify CNVs. Characterization of widespread constitutional CNVs offers insight into their role in disease susceptibility, whereas somatic CNVs identify regions of the genome involved in disease phenotype. The role of CNVs in cancer has only emerged in the last 2 years, with constitutional CNVs originally being observed in the Li-Fraumeni cancer susceptibility syndrome, and more recently in neuroblastoma. SUMMARY It is not yet known how common or how functionally relevant CNVs will be to the process of carcinogenesis. Nonetheless, the inherent instability and structural variability that characterize cancer cell genomes make this form of genetic variation particularly intriguing to the study of cancer.
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Abstract
Retinoblastoma (Rb) is a malignant tumor that originates from developing retina. Diagnosis based on clinical signs and symptoms and is usually made in children under the age of five years. Mutations in both alleles of the RB1 gene are a prerequisite for this tumor to develop. In most patients with sporadic unilateral Rb, both RB1 gene mutations occur in somatic cells and are not passed over to offspring (nonhereditary Rb). Almost all patients with sporadic bilateral and virtually all patients with familial Rb are heterozygous for RB1 gene mutations that cause predisposition to Rb (hereditary Rb). In families, Rb predisposition is transmitted as an autosomal dominant trait (familial Rb). In addition to Rb, patients with hereditary disease also have an increased risk of tumors outside the eye (second cancer). This risk is enhanced in patients who have received external beam radiotherapy. Analysis of genotype-phenotype associations has shown that the mean number of tumor foci that develop in carriers of mutant RB1 alleles is variable depending on which functions of the normal allele are retained and to what extent. Moreover, phenotypic expression of hereditary retinoblastoma is subject to genetic modification. Identification of the genetic factors that underlie these effects will not only help to arrive at a more precise prognosis but may also point to mechanisms that can be used to reduce the risk of tumor development.
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Affiliation(s)
- Dietmar Lohmann
- Institut fur Humangenetik, Universitatsklinikum Essen, Hufelandstrasse 55, D-45122 Essen, Germany.
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20
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21
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Abstract
DNA copy number variations (CNVs) are an important component of genetic variation, affecting a greater fraction of the genome than single nucleotide polymorphisms (SNPs). The advent of high-resolution SNP arrays has made it possible to identify CNVs. Characterization of widespread constitutional (germline) CNVs has provided insight into their role in susceptibility to a wide spectrum of diseases, and somatic CNVs can be used to identify regions of the genome involved in disease phenotypes. The role of CNVs as risk factors for cancer is currently underappreciated. However, the genomic instability and structural dynamism that characterize cancer cells would seem to make this form of genetic variation particularly intriguing to study in cancer. Here, we provide a detailed overview of the current understanding of the CNVs that arise in the human genome and explore the emerging literature that reveals associations of both constitutional and somatic CNVs with a wide variety of human cancers.
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Affiliation(s)
- Adam Shlien
- Departments of Genetics and Genome Biology and Division of Hematology/Oncology, Hospital for Sick Children, University of Toronto, Toronto, Ontario, Canada, M5G 1X8
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22
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Abstract
DNA copy number variations (CNVs) are an important component of genetic variation, affecting a greater fraction of the genome than single nucleotide polymorphisms (SNPs). The advent of high-resolution SNP arrays has made it possible to identify CNVs. Characterization of widespread constitutional (germline) CNVs has provided insight into their role in susceptibility to a wide spectrum of diseases, and somatic CNVs can be used to identify regions of the genome involved in disease phenotypes. The role of CNVs as risk factors for cancer is currently underappreciated. However, the genomic instability and structural dynamism that characterize cancer cells would seem to make this form of genetic variation particularly intriguing to study in cancer. Here, we provide a detailed overview of the current understanding of the CNVs that arise in the human genome and explore the emerging literature that reveals associations of both constitutional and somatic CNVs with a wide variety of human cancers.
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Affiliation(s)
- Adam Shlien
- Departments of Genetics and Genome Biology and Division of Hematology/Oncology, Hospital for Sick Children, University of Toronto, Toronto, Ontario, Canada, M5G 1X8
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23
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Abouzeid H, Schorderet DF, Balmer A, Munier FL. Germline mutations in retinoma patients: relevance to low-penetrance and low-expressivity molecular basis. Mol Vis 2009; 15:771-7. [PMID: 19390654 PMCID: PMC2671583] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2008] [Accepted: 04/03/2009] [Indexed: 12/05/2022] Open
Abstract
PURPOSE To study phenotype-genotype correlation in patients who have retinoma, which is a benign tumor resembling the post irradiation regression pattern of retinoblastoma (RB). METHODS We selected patients who had retinoma and positive family history for RB and patients who had retinoma in one eye and either retinoma or RB in the other eye. The study included 22 patients with available DNA: 18 from 11 families and four sporadic cases. DNA was extracted from peripheral blood leukocytes. The RB1 gene was screened by DHPLC and direct sequencing of the promoter and all the exons. RESULTS We identified 17 occurrences of 11 distinct germline mutations in two sporadic and in 15 familial cases (nine families). The 11 identified mutations were located in exons 1, 10,11,13,14, and 19 to 23. Four of the identified mutations were not previously reported, including g.64407delT, g.153236A>T, g.156743delTCTG, and g.162078delA. Eight out the 11 mutations were truncating and three were nontruncating (missense). There was no correlation between the type of mutation and the number of tumor foci per eye (RB or retinomas). Highly heterogeneous intrafamilial expressivity was observed. CONCLUSIONS To our knowledge, this study is the largest series of mutations of consecutive retinoma patients. The present data suggest that the type of inherited mutations underlying retinoma is undistinguishable from RB related ones, i.e., largely dominated by truncating mutants. This finding is in contrast with the RB1 genotypic spectrum of mutations associated with low-penetrance RB, i.e., nontruncating mutants. The molecular mechanism underlying low-penetrance and attenuated expressivity (retinomas) appeared to be distinct.
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Affiliation(s)
| | - Daniel F. Schorderet
- Institut de Recherche en Ophtalmologie (IRO), Sion, Switzerland,Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
| | | | - Francis L. Munier
- Jules-Gonin Eye Hospital, Lausanne, Switzerland,Institut de Recherche en Ophtalmologie (IRO), Sion, Switzerland
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Park Y, Kubo A, Komiya T, Coxon A, Beebe K, Neckers L, Meltzer PS, Kaye FJ. Low-penetrant RB allele in small-cell cancer shows geldanamycin instability and discordant expression with mutant ras. Cell Cycle 2008; 7:2384-91. [PMID: 18677112 DOI: 10.4161/cc.6363] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Certain kindreds with low-penetrant (lp) retinoblastoma carry mutant alleles which retain partial tumor suppressor activity and we previously showed that these alleles exhibit defective, temperature-sensitive binding in yeast. To investigate the molecular basis for incomplete penetrance, we studied three recurrent lp alleles and observed approximately 50% of wildtype activity measured by (i) phosphorylation at key regulatory sites, S780, S795, S807/S811, (ii) transcriptional co-activation, and (iii) 'flat-cell' differentiation in mammalian cells in vivo. In addition, we studied a small-cell carcinoma that is homozygous for the R661W allele providing the first analysis of the effect of a naturally occurring lp allele in a human tumor. While we detected abundant expression of the R661W protein, we noted marked instability of both endogenous and recombinant R661W following treatment in vivo with the Hsp90 inhibitor, geldanamycin and stabilization of R661W following heat shock. In addition, we observed a discordant phenotype in the tumor cells with induction of p16 and loss of cyclin D1 consistent with a null RB status combined with homozygous expression of mutant ras which had not been reported previously for RB (-) small-cell cancer. These findings show that a recurrent missense lp allele retains greater functional activity in vivo than predicted from earlier in vitro assays, proposing a role for stabilizing chaperone-like activity in vivo. In addition, these data suggest that reversible protein instability and the requirement for a cooperating mutation may provide a stochastic explanation for the molecular basis of incomplete penetrance in kindreds carrying these alleles.
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Affiliation(s)
- Yoonsoo Park
- Genetics Branch, Center for Cancer Research, National Cancer Institute and National Naval Medical Center, Bethesda, Maryland 20889, USA
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25
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Dick FA. Structure-function analysis of the retinoblastoma tumor suppressor protein - is the whole a sum of its parts? Cell Div 2007; 2:26. [PMID: 17854503 PMCID: PMC2082274 DOI: 10.1186/1747-1028-2-26] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2007] [Accepted: 09/13/2007] [Indexed: 12/28/2022] Open
Abstract
Biochemical analysis of the retinoblastoma protein's function has received considerable attention since it was cloned just over 20 years ago. During this time pRB has emerged as a key regulator of the cell division cycle and its ability to block proliferation is disrupted in the vast majority of human cancers. Much has been learned about the regulation of E2F transcription factors by pRB in the cell cycle. However, many questions remain unresolved and researchers continue to explore this multifunctional protein. In particular, understanding how its biochemical functions contribute to its role as a tumor suppressor remains to be determined. Since pRB has been shown to function as an adaptor molecule that links different proteins together, or to particular promoters, analyzing pRB by disrupting individual protein interactions holds tremendous promise in unraveling the intricacies of its function. Recently, crystal structures have reported how pRB interacts with some of its molecular partners. This information has created the possibility of rationally separating pRB functions by studying mutants that disrupt individual binding sites. This review will focus on literature that investigates pRB by isolating functions based on binding sites within the pocket domain. This article will also discuss the prospects for using this approach to further explore the unknown functions of pRB.
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Taylor M, Dehainault C, Desjardins L, Doz F, Levy C, Sastre X, Couturier J, Stoppa-Lyonnet D, Houdayer C, Gauthier-Villars M. Genotype-phenotype correlations in hereditary familial retinoblastoma. Hum Mutat 2007; 28:284-93. [PMID: 17096365 DOI: 10.1002/humu.20443] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
We studied 50 unrelated pedigrees with a family history of retinoblastoma (Rb) (165 carriers of a RB1 mutation) to delineate the spectrum of RB1 germline mutations in familial Rb and to identify genotype-phenotype correlations as well as putative modifiers. Patients were followed at Institut Curie and they were examined by an ophthalmologist, a pediatrician, and a geneticist. All cases of familial Rb were determined via genetic counseling. Clinical features included disease status, laterality, age at diagnosis, mutation type, follow-up, and disease-eye ratio (DER). To eliminate mosaic cases, first-generation carriers displaying low-penetrance (LP) Rb were excluded from the analysis. Complete penetrance was the rule for nonsense and frameshift mutations (25 families) and high penetrance was observed for large rearrangements (eight families). Promoter (two families) and missense (two families) mutations displayed heterogeneous phenotypes and LP. Variable penetrance was observed for splice abnormalities (13 families) and was explained by in/out of frame mutations or respect of functional domains. Surprisingly, two families with the LP g.45867G>T/IVS6+1G>T mutation presented data that conflicted with the data reported in previous publications, as unaffected carriers had paternally inherited mutant alleles. Moreover, RNA analyses suggested that the lack of penetrance in unaffected carriers could be explained by an increase in expression levels of the wild-type allele. This observation prompted us to define a new class "3" of LP alleles. We believe this is the first large-scale study of familial Rb with a high level of homogeneity in the clinical and genetic analysis of patients and their relatives, thereby allowing for reliable intrafamilial genotype-phenotype correlations. Our analysis suggests in some cases the influence of modifier factors probably involved in mRNA level regulation and/or pRB pathway regulation.
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Affiliation(s)
- Melissa Taylor
- Service d'Oncologie Pédiatrique, Institut Curie, Paris, France
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27
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Sánchez-Sánchez F, Ramírez-Castillejo C, Weekes DB, Beneyto M, Prieto F, Nájera C, Mittnacht S. Attenuation of disease phenotype through alternative translation initiation in low-penetrance retinoblastoma. Hum Mutat 2007; 28:159-67. [PMID: 16988938 DOI: 10.1002/humu.20394] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Hereditary predisposition to retinoblastoma (RB) is caused by germline mutations in the retinoblastoma 1 (RB1) gene and transmits as an autosomal dominant trait. In the majority of cases disease develops in greater than 90% of carriers. However, reduced penetrance with a large portion of disease-free carrier is seen in some families. Unambiguous identification of the predisposing mutation in these families is important for accurate risk prediction in relatives and their genetic counseling but also provides conceptual information regarding the relationship between the RB1 genotype and the disease phenotype. In this study we report a novel mutation detected in 10 individuals of an extended family, only three of whom are affected by RB disease. The mutation comprises a 23-basepair (bp) duplication in the first exon of RB1 (c.43_65dup) producing a frameshift in exon 1 and premature chain termination in exon 2. Mutations resulting in premature chain termination classically are associated with high penetrance disease, as message translation may not generate functional product and nonsense mediated RNA decay (NMD) frequently eliminates the mutant transcript. However, appreciable NMD does not follow from the mutation described here and transcript expression in tissue culture cells and translation in vitro reveals that alternative in-frame translation start sites involving Met113 and possibly Met233 are used to generate truncated RB1 products (pRB94 and pRB80), known and suspected to exhibit tumor suppressor activity. These results strongly suggest that modulation of disease penetrance in this family is achieved by internal translation initiation. Our observations provide the first example for rescue of a chain-terminating mutation in RB1 through alternative translation initiation.
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Affiliation(s)
- Francisco Sánchez-Sánchez
- Departamento de Genética, Facultad de Biología, Universidad de Valencia, Burjassot, Valencia, Spain.
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28
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Abstract
Retinoblastoma is the most common primary intraocular tumor in childhood. Mutations in both the alleles of the RB1 gene represent the causative agent for the tumor to occur. It is becoming evident that, although these alterations represent key events in the genesis of retinoblastoma, they are not sufficient per se for the tumor to develop, and other additional genetic or epigenetic alterations must occur. A supportive role in the genesis of retinoblastoma has recently been proposed for the RB1-related gene RB2/p130. Additionally, several other genetic alterations involving different chromosomes have been described as relevant in the tumorigenic process. In this review we will analyse current knowledge about the molecular mechanisms involved in retinoblastoma, paying particular attention to the mechanisms of inactivation of the biological function of the retinoblastoma family of proteins.
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Affiliation(s)
- G De Falco
- Department of Human Pathology and Oncology, University of Siena, Siena, Italy
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29
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Albrecht P, Ansperger-Rescher B, Schüler A, Zeschnigk M, Gallie B, Lohmann DR. Spectrum of gross deletions and insertions in the RB1 gene in patients with retinoblastoma and association with phenotypic expression. Hum Mutat 2006; 26:437-45. [PMID: 16127685 DOI: 10.1002/humu.20234] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
Quantitative multiplex PCR and genomic real-time PCR were used to complete an RB1 mutation analysis in 57 of 433 and 72 of 262 patients with hereditary and isolated unilateral retinoblastoma, respectively. These patients were selected because in previous analyses, which focused mainly on the identification of point mutations, no RB1 mutation was found. We identified gross deletions and insertions in peripheral blood DNA from 26 of 57 patients (46%) with hereditary retinoblastoma, and in six of 72 patients (8.3%) with isolated unilateral disease. In addition, we identified 32 somatic mutations in tumor DNA from 31 of 72 patients (43%) with isolated unilateral retinoblastoma. Together with our previous results, we found that gross RB1 alterations were present in the peripheral blood DNA from 65 of 433 (15%) and 17 of 262 (6.5%) patients with bilateral or familial and isolated unilateral retinoblastoma, respectively. Including reported gross deletions, an analysis of the frequency of breakpoints per intron length shows higher densities in introns 13, 16, 23, and 24. Genotype-phenotype analyses showed that on the whole, carriers of gross deletions develop fewer retinoblastomas compared to patients who are heterozygous for other types of RB1 null mutations. Specifically, carriers of cytogenetic and submicroscopic whole gene deletions often have unilateral tumors only. By contrast, almost all patients with gross deletions with one breakpoint in RB1 have bilateral retinoblastoma.
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Affiliation(s)
- P Albrecht
- Institut für Humangenetik, Universität Duisburg-Essen, Essen, Germany
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30
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Godefroy N, Lemaire C, Mignotte B, Vayssière JL. p53 and Retinoblastoma protein (pRb): A complex network of interactions. Apoptosis 2006; 11:659-61. [PMID: 16554964 DOI: 10.1007/s10495-006-5543-y] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Affiliation(s)
- N Godefroy
- Laboratoire de Génétique et Biologie Cellulaire (CNRS UMR8159), Université de Versailles Saint-Quentin-en-Yvelines, 45 Avenue des Etats-Unis, 78035, Versailles Cedex, France
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Brichard B, Heusterspreute M, De Potter P, Chantrain C, Vermylen C, Sibille C, Gala JL. Unilateral retinoblastoma, lack of familial history and older age does not exclude germline RB1 gene mutation. Eur J Cancer 2006; 42:65-72. [PMID: 16343894 DOI: 10.1016/j.ejca.2005.07.027] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2005] [Accepted: 07/17/2005] [Indexed: 12/13/2022]
Abstract
Conclusive identification of RB1 mutations in retinoblastoma is predicted to improve the clinical management of affected children and relatives. However, despite clear clinical benefits, RB1 screening remains difficult, most of the alterations being unique and randomly distributed throughout the entire coding sequence. In this report, we present the results of a constitutional RB1 analysis undertaken in our institution over the last four years. The detection of RB1 gene deletion or mutation was performed by Southern blot and sequence analyses in 73 patients (including three families with 2, 3 and 3 probands, respectively). Complementary constitutional chromosome and fluorescent in situ hybridization (FISH) analyses of RB1 gene were applied in cases where hereditary retinoblastoma was suspected despite negative detection. Altogether, germline abnormalities were found in 11% (4/36 patients) of sporadic unilateral retinoblastoma (median age, 21.5 months) and 86% (32/37 patients) of sporadic bilateral or positive familial history retinoblastoma (median age, 5 months). The spectrum of germline alterations found in 31 distinct families included 12 nonsense mutations (39%); 10 point insertions or deletions with frameshift (32%); 4 mutations and 1 deletion affecting splice sites (16%); 2 missense mutations (6%); and 2 large deletions (6%). A total of 15 mutations have not been previously reported. In this small series, splicing mutations were associated with bilateral disease whilst most of the frameshift mutations were identified in patients with an early age at diagnosis, bilateral disease or hereditary forms of the disease. This study confirms that screening for constitutional RB1 mutation should become an integral part of current management of any patient affected by retinoblastoma irrespective of the tumour laterality and familial background.
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Affiliation(s)
- Bénédicte Brichard
- Department of Pediatric Haematology and Oncology, Cliniques Universitaires Saint-Luc, Université Catholique de Louvain, Avenue Hippocrate 10, B-1200 Brussels, Belgium.
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Sampieri K, Hadjistilianou T, Mari F, Speciale C, Mencarelli MA, Cetta F, Manoukian S, Peissel B, Giachino D, Pasini B, Acquaviva A, Caporossi A, Frezzotti R, Renieri A, Bruttini M. Mutational screening of the RB1 gene in Italian patients with retinoblastoma reveals 11 novel mutations. J Hum Genet 2006; 51:209-216. [PMID: 16463005 DOI: 10.1007/s10038-005-0348-3] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2005] [Accepted: 11/06/2005] [Indexed: 01/19/2023]
Abstract
Retinoblastoma (RB, OMIM#180200) is the most common intraocular tumour in infancy and early childhood. Constituent mutations in the RB1 gene predispose individuals to RB development. We performed a mutational screening of the RB1 gene in Italian patients affected by RB referred to the Medical Genetics of the University of Siena. In 35 unrelated patients, we identified germline RB1 mutations in 6 out of 9 familial cases (66%) and in 7 out of 26 with no family history of RB (27%). Using the single-strand conformational polymorphism (SSCP) technique, 11 novel mutations were detected, including 3 nonsense, 5 frameshift and 4 splice-site mutations. Only two of these mutations (1 splice site and 1 missense) were previously reported. The mutation spectrum reflects the published literature, encompassing predominately nonsense or frameshift and splicing mutations. RB1 germline mutation was detected in 37% of our cases. Gross rearrangements outside the investigated region, altered DNA methylation, or mutations in non-coding regions, may be the cause of disease in the remainder of the patients. Some cases, e.g. a case of incomplete penetrance, or variable expressivity ranging from retinoma to multiple tumours, are discussed in detail. In addition, a case of pre-conception genetic counselling resolved by rescue of banked cordonal blood of the affected deceased child is described.
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Affiliation(s)
- Katia Sampieri
- Medical Genetics, Molecular Biology Department, University of Siena, Policlinico Le Scotte, viale Bracci 2, 53100, Siena, Italy
| | | | - Francesca Mari
- Medical Genetics, Molecular Biology Department, University of Siena, Policlinico Le Scotte, viale Bracci 2, 53100, Siena, Italy
| | - Caterina Speciale
- Medical Genetics, Molecular Biology Department, University of Siena, Policlinico Le Scotte, viale Bracci 2, 53100, Siena, Italy
| | - Maria Antonietta Mencarelli
- Medical Genetics, Molecular Biology Department, University of Siena, Policlinico Le Scotte, viale Bracci 2, 53100, Siena, Italy
| | | | - Siranoush Manoukian
- Medical Genetics, Experimental Oncology, Instituto Nazionale Tumori , Milan, Italy
| | - Bernard Peissel
- Medical Genetics, Experimental Oncology, Instituto Nazionale Tumori , Milan, Italy
| | | | - Barbara Pasini
- Genetics, Biology and Biochemistry Department, University of Torino, Turin, Italy
| | | | - Aldo Caporossi
- Ophtalmological Science and Neuroscience, Siena General Hospital, Siena, Italy
| | | | - Alessandra Renieri
- Medical Genetics, Molecular Biology Department, University of Siena, Policlinico Le Scotte, viale Bracci 2, 53100, Siena, Italy
| | - Mirella Bruttini
- Medical Genetics, Molecular Biology Department, University of Siena, Policlinico Le Scotte, viale Bracci 2, 53100, Siena, Italy.
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Dannenberg JH, te Riele HPJ. The retinoblastoma gene family in cell cycle regulation and suppression of tumorigenesis. Results Probl Cell Differ 2006; 42:183-225. [PMID: 16903212 DOI: 10.1007/400_002] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
Since its discovery in 1986, as the first tumor suppressor gene, the retinoblastoma gene (Rb) has been extensively studied. Numerous biochemical and genetic studies have elucidated in great detail the function of the Rb gene and placed it at the heart of the molecular machinery controlling the cell cycle. As more insight was gained into the genetic events required for oncogenic transformation, it became clear that the retinoblastoma gene is connected to biochemical pathways that are dysfunctional in virtually all tumor types. Besides regulating the E2F transcription factors, pRb is involved in numerous biological processes such as apoptosis, DNA repair, chromatin modification, and differentiation. Further complexity was added to the system with the discovery of p107 and p130, two close homologs of Rb. Although the three family members share similar functions, it is becoming clear that these proteins also have unique functions in differentiation and regulation of transcription. In contrast to Rb, p107 and p130 are rarely found inactivated in human tumors. Yet, evidence is accumulating that these proteins are part of a "tumor-surveillance" mechanism and can suppress tumorigenesis. Here we provide an overview of the knowledge obtained from studies involving the retinoblastoma gene family with particular focus on its role in suppressing tumorigenesis.
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Affiliation(s)
- Jan-Hermen Dannenberg
- Department of Medical Oncology, Dana-Farber Cancer Institute and Harvard Medical School, Boston, Massachusetts, USA.
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34
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Murphree AL, Samuel MA, Harbour JW, Mansfield NC. Retinoblastoma. Retina 2006. [DOI: 10.1016/b978-0-323-02598-0.50028-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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35
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Valverde JR, Alonso J, Palacios I, Pestaña Á. RB1 gene mutation up-date, a meta-analysis based on 932 reported mutations available in a searchable database. BMC Genet 2005; 6:53. [PMID: 16269091 PMCID: PMC1298292 DOI: 10.1186/1471-2156-6-53] [Citation(s) in RCA: 110] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2005] [Accepted: 11/04/2005] [Indexed: 11/16/2022] Open
Abstract
Background Retinoblastoma, a prototype of hereditary cancer, is the most common intraocular tumour in children and potential cause of blindness from therapeutic eye ablation, second tumours in germ line carrier's survivors, and even death when left untreated. The molecular scanning of RB1 in search of germ line mutations lead to the publication of more than 900 mutations whose knowledge is important for genetic counselling and the characterization of phenotypic-genotypic relationships. Results A searchable database (RBGMdb) has been constructed with 932 published RB1 mutations. The spectrum of these mutations has been analyzed with the following results: 1) the retinoblastoma protein is frequently inactivated by deletions and nonsense mutations while missense mutations are the main inactivating event in most genetic diseases. 2) Near 40% of RB1 gene mutations are recurrent and gather in sixteen hot points, including twelve nonsense, two missense and three splicing mutations. The remainder mutations are scattered along RB1, being most frequent in exons 9, 10, 14, 17, 18, 20, and 23. 3) The analysis of RB1 mutations by country of origin of the patients identifies two groups in which the incidence of nonsense and splicing mutations show differences extremely significant, and suggest the involvement of predisposing ethnic backgrounds. 4) A significant association between late age at diagnosis and splicing mutations in bilateral retinoblastoma patients suggests the occurrence of a delayed-onset genotype. 5) Most of the reported mutations in low-penetrance families fall in three groups: a) Mutations in regulatory sequences at the promoter resulting in low expression of a normal Rb; b) Missense and in-frame deletions affecting non-essential sequence motifs which result in a partial inactivation of Rb functions; c) Splicing mutations leading to the reduction of normal mRNA splicing or to alternative splicing involving either true oncogenic or defective (weak) alleles. Conclusion The analysis of RB1 gene mutations logged in the RBGMdb has shown relevant phenotype-genotype relationships and provided working hypothesis to ascertain mechanisms linking certain mutations to ethnicity, delayed onset of the disease and low-penetrance. Gene profiling of tumors will help to clarify the genetic background linked to ethnicity and variable expressivity or delayed onset phenotypes.
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Affiliation(s)
- José R Valverde
- Servicio de Informática. Centro Nacional de Biotecnología, CSIC. Campus de Cantoblanco. 28049-Madrid, Spain
| | - Javier Alonso
- Oncolab. Deparatamento de Biología Molecular y Celular del Cáncer. Instituto de Investigaciones Biomédicas "A. Sols", CSIC-UAM. 28029 Madrid, Spain
| | - Itziar Palacios
- Oncolab. Deparatamento de Biología Molecular y Celular del Cáncer. Instituto de Investigaciones Biomédicas "A. Sols", CSIC-UAM. 28029 Madrid, Spain
| | - Ángel Pestaña
- Oncolab. Deparatamento de Biología Molecular y Celular del Cáncer. Instituto de Investigaciones Biomédicas "A. Sols", CSIC-UAM. 28029 Madrid, Spain
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Sdek P, Ying H, Zheng H, Margulis A, Tang X, Tian K, Xiao ZXJ. The central acidic domain of MDM2 is critical in inhibition of retinoblastoma-mediated suppression of E2F and cell growth. J Biol Chem 2004; 279:53317-22. [PMID: 15485814 DOI: 10.1074/jbc.m406062200] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Retinoblastoma (Rb) protein is a paradigm of tumor suppressors. Inactivation of Rb plays a critical role in the development of human malignancies. MDM2, an oncogene frequently found amplified and overexpressed in a variety of human tumors and cancers, directly interacts and inhibits the p53 tumor suppressor protein. In addition, MDM2 has been shown to stimulate E2F transactivation activity and promote S-phase entry independent of p53, yet the mechanism of which is still not fully understood. In this study, we demonstrate that MDM2 specifically binds to Rb C-pocket and that the central acidic domain of MDM2 is essential for Rb interaction. In addition, we show that overexpression of MDM2 reduces Rb-E2F complexes in vivo. Moreover, the ectopic expression of the wild type MDM2, but not mutant MDM2 defective in Rb interaction, stimulates E2F transactivation activity and inhibits Rb growth suppression function. Taken together, these results suggest that MDM2-mediated inhibition of Rb likely contributes to MDM2 oncogenic activity.
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Affiliation(s)
- Patima Sdek
- Department of Biochemistry, Boston University School of Medicine, Boston, MA 02118, USA
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37
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Lohmann DR, Gallie BL. Retinoblastoma: revisiting the model prototype of inherited cancer. AMERICAN JOURNAL OF MEDICAL GENETICS PART C-SEMINARS IN MEDICAL GENETICS 2004; 129C:23-8. [PMID: 15264269 DOI: 10.1002/ajmg.c.30024] [Citation(s) in RCA: 117] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Hereditary retinoblastoma is an autosomal dominant disorder caused by mutations in the RB1 gene. Analysis of this rare condition has helped to elucidate the mechanisms underlying hereditary cancer predisposition in general. As identification of RB1 gene mutations has become a part of clinical management of patients with retinoblastoma, there is now a wealth of data. In this article, we summarize the current knowledge on the relations between the genotype and phenotypic expression. Moreover, detailed analysis of genotype-phenotype relations shows that hereditary retinoblastoma has features of a complex trait.
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Affiliation(s)
- Dietmar R Lohmann
- Institut für Humangenetik, Hufelandstrasse 55, D-45122 Essen, Germany.
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38
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Korswagen LA, Moll AC, Imhof SM, Schouten-van Meeteren AYN. A second primary tumor in a patient with retinoma. Ophthalmic Genet 2004; 25:45-8. [PMID: 15255114 DOI: 10.1076/opge.25.1.45.29006] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
AIM To evaluate the frequency of the co-occurrence of a retinoma and another primary tumor. METHOD Presentation of a case report and review of the literature. RESULTS A cutaneous melanoma was observed in a 52-year-old man, who was known to have two retinomas in the right eye. Five other cases were found in a review of the literature, suggesting the possibility of an increased risk of developing a second primary tumor in patients with retinoma. The occurrence of cutaneous melanoma as a second primary tumor after retinoma and/or retinoblastoma is discussed. CONCLUSION There might be an increased risk for patients with retinoma to develop another primary tumor, necessitating regular follow-up of these patients.
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Affiliation(s)
- Lindy-Anne Korswagen
- Department of Ophthalmology, VU University Medical Center, Amsterdam, The Netherlands
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39
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Skrypnyk C, Bartsch O. Retinoblastoma, pinealoma, and mild overgrowth in a boy with a deletion ofRB1 and neighbor genes on chromosome 13q14. ACTA ACUST UNITED AC 2004; 124A:397-401. [PMID: 14735589 DOI: 10.1002/ajmg.a.20410] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
We report on a 10-year-old boy with a normal karyotype and a chromosome 13q14 deletion of the retinoblastoma gene (RB1) by fluorescence in situ hybridization (FISH). He showed subtle signs of overgrowth, including macrocephaly, hepatomegaly, and inguinal hernia. The boy also had cryptorchism and mild developmental delay. In his first months of life, variant Wiedemann-Beckwith syndrome was tentatively suspected and he was included in a careful tumor prevention program. At the age of 11 months, bifocal retinoblastoma of the left eye was diagnosed. Pinealoma was suspected at the age of 19 months and was removed by neurosurgery at the age of 29 months. At 4 years and 4 months, the deletion of the RB1 gene was suspected on clinical grounds and was diagnosed by FISH and molecular studies. At that time, he was a near-normal healthy playful kindergarten child, height 107 cm (-0.3 SD), OFC 52.5 cm (+0.8 SD), developmental age 3-3.5 years. The combination of retinoblastoma, pinealoma, and deletion of the RB1 gene diagnosed by FISH has not been reported previously. The deletion spans at least 370-420 kb in size and is predicted to include proximal and distal neighbor genes. This report may assist in establishing the clinical signs of the contiguous gene syndrome at the RB1 locus on 13q14.
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Affiliation(s)
- Cristina Skrypnyk
- Institute of Clinical Genetics, Dresden University of Technology, Fetscherstrasse 74, D-01307 Dresden, Germany
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40
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Abstract
Pediatricians are often the health care providers who first detect the signs and symptoms of childhood cancer. Although pediatric malignancies are rare diseases, early diagnosis is an important factor leading to high cure rates of many types of cancers including retinoblastomara, Wilms' tumor, hepatoblastoma, rhabdomyosarcoma. thyroid carcinoma, and other solid tumors. A number of familial cancer syndromes present with childhood cancers that can be recognized or diagnosed by pediatricians. The genetic origins of several syndromes have been elucidated. Genetic testing is not yet available for all of these inherited cancers. A frequently updated list of genetic tests is available at www.genetests.org. The ordering and interpreting of genetic tests, however, is often best done by trained genetic counselors. The pediatrician will play a vital on-going role in following the at-risk child. In many of syndromes discussed, the cost effectiveness of the tests as well as that of any potential intervention needs further study. The role of the subtle genetic polymorphisms in pediatric tumorigenesis. many more of which will undoubtedly be described in the coming years, has not yet been translated into defined needs for interventions. Perhaps in the future it will be possible to understand the additive effect of multiple genetic polymorphisms and to determine genetic profiles of high cancer risk. Until suitable interventions are established, however, the study of genetic variability and cancer will await practical significance. Undoubtedly other major important cancer genes are yet to be discovered and characterized. An additional challenge is the counseling and management of children and adults who have a strong family history of cancer yet who do not have a recognizable syndrome. The role of the primary pediatrician is to recognize the major cancer genetic syndromes, to make appropriate referrals for genetic counseling and testing when indicated, and to ensure that adequate screening tests are being done.
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Affiliation(s)
- Samart Pakakasama
- Department of Pediatrics, Ramathibodi Hospital, Rama VI Road, Bangkok 10400, Thailand
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41
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Fang W, Mori T, Cobrinik D. Regulation of PML-dependent transcriptional repression by pRB and low penetrance pRB mutants. Oncogene 2002; 21:5557-65. [PMID: 12165854 DOI: 10.1038/sj.onc.1205666] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2002] [Revised: 04/25/2002] [Accepted: 05/10/2002] [Indexed: 11/09/2022]
Abstract
The retinoblastoma protein (pRB) is thought to suppress tumorigenesis, in part, through interactions with E2F transcription factors. However, certain low penetrance pRB mutants substantially reduce tumor incidence despite having a minimal ability to bind E2F. These low penetrance mutants retain the ability to induce a senescence-like state, suggesting that they may suppress tumorigenesis through a senescence-associated process. Here, we identify a novel pRB function that is associated with senescence and which is retained by non-E2F binding low penetrance pRB mutants. It was found that pRB and these mutants substantially increased the production of PML nuclear bodies (NBs). In keeping with the role of PML in transcriptional repression, pRB also promoted PML-dependent transcriptional repression by the c-Myc antagonist Mad1. In a series of pRB-p130 chimeric proteins, the ability to increase NB production correlated with the ability to induce a senescence-like phenotype. However, neither NB formation nor PML function were required for pRB to induce the senescence-like response. Together, these observations indicate that a pRB-induced increase in PML NB formation is coordinated with, but separable from, the pRB-induced senescence program. The data further suggest that PML may contribute to an E2F-independent tumor suppressor function of pRB.
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Affiliation(s)
- Weizhao Fang
- Department of Medicine, College of Physicians and Surgeons of Columbia University, New York, NY 10032, USA
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42
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Klutz M, Brockmann D, Lohmann DR. A parent-of-origin effect in two families with retinoblastoma is associated with a distinct splice mutation in the RB1 gene. Am J Hum Genet 2002; 71:174-9. [PMID: 12016586 PMCID: PMC384976 DOI: 10.1086/341284] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2002] [Accepted: 04/15/2002] [Indexed: 11/03/2022] Open
Abstract
We have identified a splice-site mutation (IVS6+1G-->T) in the RB1 gene, in two unrelated families with incomplete-penetrance retinoblastoma. Analysis of RNA from white blood cells showed that this mutation causes skipping of exon 6. Although this deletion results in a frameshift, most carriers of the mutation did not develop retinoblastoma. Interestingly, the relative abundance of the resultant nonsense messenger RNA varies between members of the same family and is either similar to or considerably lower than the transcript level of the normal allele. Moreover, variation of relative transcript levels is associated with both the sex of the parent that transmitted the mutant allele and phenotypic expression: All eight carriers with similar abundance of nonsense and normal transcript have received the mutant allele from their mother, and only one of them has developed retinoblastoma; by contrast, all eight carriers with reduced abundance of the nonsense transcript have received the mutant allele from their father, and all but two them have retinoblastoma. After treatment with cycloheximide, the relative abundance of transcripts from paternally inherited mutant alleles was partly restored, thus indicating that posttranscriptional mechanisms, rather than transcriptional silencing, are responsible for low levels of mutant messenger RNA. Our data suggest that a specific RB1 mutation can be associated with differential penetrance, on the basis of the sex of the transmitting parent.
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Affiliation(s)
- Martina Klutz
- Institut für Humangenetik, Universitätsklinikum Essen, Germany
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43
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Nájera C, Sánchez F, Mateu E, Prieto F, Beneyto M. [Early diagnosis of retinoblastoma: usefulness of searching for RB1 gene mutations]. Med Clin (Barc) 2001; 116:365-72. [PMID: 11333669 DOI: 10.1016/s0025-7753(01)71832-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
BACKGROUND Retinoblastoma, the intraocular malignancy most common in children,occurs in both familial and sporadic (bilateral or unilateral). Hereditary predisposition is caused by a germ-line mutation while non-hereditary is due to two somatic mutations in a retinal cell. This work was carried out in order to analyse genetically, the high number of families with some affected member and to go deep into the molecular mechanisms responsible of this pathology. PATIENTS AND METHOD 59 families with one or more affected members were analysed. Cytogenetics and with polymorphic markers studies were carried out and a search for mutations was performed in DNA from white cells and from available tumoral tissue. RESULTS In four of the 5 familial cases, the responsible mutation was established,the same as in 9 of the 13 bilateral sporadic. In the 7% of the unilateral sporadic cases, mutation was found in leucocytary DNA. Lost of heterozygosity as a second mutational event was mainly due to mitotic recombination. CONCLUSIONS Among the mutations of our series, a higher frequency of punctual mutations,responsible of the first mutational event, was observed at constitutional level. Lost of heterozygosity was the mechanism observed in the majority of the tumours.
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Affiliation(s)
- C Nájera
- Departamento de Genética. Facultad de Ciencias Biológicas. Universitat de Valencia.
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44
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Alonso J, García-Miguel P, Abelairas J, Mendiola M, Pestaña A. A microsatellite fluorescent method for linkage analysis in familial retinoblastoma and deletion detection at the RB1 locus in retinoblastoma and osteosarcoma. DIAGNOSTIC MOLECULAR PATHOLOGY : THE AMERICAN JOURNAL OF SURGICAL PATHOLOGY, PART B 2001; 10:9-14. [PMID: 11277399 DOI: 10.1097/00019606-200103000-00003] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Linkage analysis at the retinoblastoma locus (RB1) is essential for identifying individuals at risk and to offer adequate genetic counseling in familial retinoblastoma. It can also be used to detect large deletions involving RB1, which accounts for 15% of the genetic alterations in hereditary retinoblastoma. These studies are usually carried out with lengthy Southern blot analyses of relatively uninformative restriction fragment length polymorphisms. The authors report an alternative, reliable protocol for genotyping the RB1 locus using two pairs of highly informative intragenic and flanking microsatellites linked closely to the RB1 gene, and analysis of the fluorescent-labeled polymerase chain reaction products with automatic sizing technology. This methodology has successfully identified high risk carriers in five of the five pedigrees of familial retinoblastoma studied. In addition, gross deletions affecting the RB1 gene were identified in two of 12 sporadic bilateral retinoblastomas, and loss of heterozygosity at the RB1 locus has been detected in one of three osteosarcomas using the same experimental protocol. The described protocol is simpler and faster than conventional Southern blot methodologies and can identify a larger number of informative cases.
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Affiliation(s)
- J Alonso
- OncoLab, Unidad de Biología Molecular y Celular del Cáncer, Instituto de Investigaciones Biomédicas, Madrid, Spain
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45
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DiCiommo D, Gallie BL, Bremner R. Retinoblastoma: the disease, gene and protein provide critical leads to understand cancer. Semin Cancer Biol 2000; 10:255-69. [PMID: 10966849 DOI: 10.1006/scbi.2000.0326] [Citation(s) in RCA: 88] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Retinoblastoma has contributed much to the understanding of cancer. The protein product of the RB gene, pRB, is a multifaceted regulator of transcription which controls the cell cycle, differentiation and apoptosis in normal development of specific tissues. Elucidating the mechanisms in which pRB plays a critical role will enable novel therapies and strategies for prevention, not only for retinoblastoma, but for cancer in general.
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Affiliation(s)
- D DiCiommo
- Departments of Molecular and Medical Genetics, University of Toronto, Toronto, Canada
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Müller H, Helin K. The E2F transcription factors: key regulators of cell proliferation. BIOCHIMICA ET BIOPHYSICA ACTA 2000; 1470:M1-12. [PMID: 10656985 DOI: 10.1016/s0304-419x(99)00030-x] [Citation(s) in RCA: 112] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Ever since its discovery, the RB-1 gene and the corresponding protein, pRB, have been a focal point of cancer research. The isolation of E2F transcription factors provided the key to our current understanding of RB-1 function in the regulation of the cell cycle and in tumor suppression. It is becoming more and more evident that the regulatory circuits governing the cell cycle are very complex and highly interlinked. Certain aspects of RB-1 function, for instance its role in differentiation, cannot be easily explained by the current models of pRB-E2F interaction. One reason is that pRB has targets different from E2F, molecules like MyoD for instance. Another reason may be that we have not completely understood the full complexity of E2F function, itself. In this review, we will try to illuminate the role of E2F in pRB- and p53-mediated tumor suppression pathways with particular emphasis on the aspect of E2F-mediated transcriptional regulation. We conclude that E2F can mediate transcriptional activation as well as transcriptional repression of E2F target genes. The net effect of E2F on the transcriptional activity of a particular gene may be the result of as yet poorly understood protein-protein interactions of E2F with other components of the transcriptional machinery, as well as it may reflect the readout of the different ways of regulating E2F activity, itself. We will discuss the relevance of a thorough understanding of E2F function for cancer therapy.
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Affiliation(s)
- H Müller
- European Institute of Oncology, Department of Experimental Oncology, Via Ripamonti 435, 20141, Milan, Italy
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Abstract
The inactivation of the p53 and Rb pathways would account for the majority of human tumours. There are many levels of cross talk between p53 and Rb that have been identified. However, the identification of the mdm2-Rb interaction established a closer link between the two most well studied tumour suppressors, p53 and Rb. Recent studies of the novel trimeric complex Rb-mdm2-p53 provided us with a functional insight of how the two tumour suppressors can act together in regulating p53 induced apoptosis. Beginning with the properties of the Rb-mdm2-p53 trimeric complex, we shall review the propounding evidence suggesting that the apoptotic function of p53 is linked to its transrepression function. The uncoupling of the apoptotic function and transactivation function of p53 will also be discussed.
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Affiliation(s)
- D B Yap
- Ludwig Institute for Cancer Research, Imperial College School of Medicine, St. Mary's campus, Norfolk Place, London, W2 1PG, UK
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Pin SS, Kariv I, Graciani NR, Oldenburg KR. Analysis of protein-peptide interaction by a miniaturized fluorescence polarization assay using cyclin-dependent kinase 2/cyclin E as a model system. Anal Biochem 1999; 275:156-61. [PMID: 10552899 DOI: 10.1006/abio.1999.4331] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
As a result of the increasing size of chemical libraries, more rapid and highly sensitive strategies are needed to accelerate the process of drug discovery without increasing the cost. One means of accomplishing this is to miniaturize the assays that enter high-throughput screening (HTS). Miniaturization requires an assay design that has few steps, has a large degree of separation between the signal and background, and has a low well to well signal variation. Fluorescence polarization (FP) is an assay type that, in many cases, meets all of the above requirements. FP is a homogenous method that allows interactions between molecules to be measured directly in solution. This article demonstrates the application of FP in a miniaturized HTS format, using 1536-well plates, to measure direct binding between cyclin-dependent kinase 2/cyclin E complex (CDK2/E) and an 8-mer-peptide kinase inhibitor. The data indicate that low variability and high specificity allow rapid and precise identification of antagonist compounds affecting CDK2/E-peptide interactions.
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Affiliation(s)
- S S Pin
- Leads Discovery, DuPont Pharmaceuticals, Experimental Station, Wilmington, Delaware 19880-0400, USA
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Varley JM, McGown G, Thorncroft M, James LA, Margison GP, Forster G, Evans DG, Harris M, Kelsey AM, Birch JM. Are there low-penetrance TP53 Alleles? evidence from childhood adrenocortical tumors. Am J Hum Genet 1999; 65:995-1006. [PMID: 10486318 PMCID: PMC1288270 DOI: 10.1086/302575] [Citation(s) in RCA: 189] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/1998] [Accepted: 07/23/1999] [Indexed: 11/03/2022] Open
Abstract
We have analyzed a panel of 14 cases of childhood adrenocortical tumors unselected for family history and have identified germline TP53 mutations in >80%, making this the highest known incidence of a germline mutation in a tumor-suppressor gene in any cancer. The spectrum of germline TP53 mutations detected is remarkably limited. Analysis of tumor tissue for loss of constitutional heterozygosity, with respect to the germline mutant allele and the occurrence of other somatic TP53 mutations, indicates complex sequences of genetic events in a number of tumors. None of the families had cancer histories that conformed to the criteria for Li-Fraumeni syndrome, but, in some families, we were able to demonstrate that the mutation had been inherited. In these families there were gene carriers unaffected in their 40s and 50s, and there were others with relatively late-onset cancers. These data provide evidence that certain TP53 alleles confer relatively low penetrance for predisposition to the development of cancer, and they imply that deleterious TP53 mutations may be more frequent in the population than has been estimated previously. Our findings have considerable implications for the clinical management of children with andrenocortical tumors and their parents, in terms of both genetic testing and the early detection and treatment of tumors.
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Affiliation(s)
- J M Varley
- Cancer Research Campaign, Section of Molecular Genetics, Paterson Institute for Cancer Research, Manchester, United Kingdom.
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Otterson GA, Modi S, Nguyen K, Coxon AB, Kaye FJ. Temperature-sensitive RB mutations linked to incomplete penetrance of familial retinoblastoma in 12 families. Am J Hum Genet 1999; 65:1040-6. [PMID: 10486322 PMCID: PMC1288236 DOI: 10.1086/302581] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
The tumor-suppressor activity of the retinoblastoma protein (RB) is encoded within a protein-binding ("pocket") domain that is targeted for mutations in all cases of familial retinoblastoma and in many common adult cancers. Although familial retinoblastoma is a paradigm for a highly penetrant, recessive model of tumorigenesis, the molecular basis for the phenotype of incomplete penetrance of familial retinoblastoma is undefined. We studied the RB pocket-binding properties of three independent, mutant RB alleles that are present in the germline of 12 kindreds with the phenotype of incomplete penetrance of familial retinoblastoma. Each arises from alterations of single codons within the RB pocket domain (designated "delta 480," "661W," or "712R"). Under the same conditions, we studied the properties of wild-type (WT) RB, an RB point mutant isolated from a lung carcinoma sample (706F) and an adjacent, in vitro-generated point mutant (707W). The delta 480, 661W, and 712R mutants lack pocket protein-binding activity in vitro but retain the WT ability to undergo cyclin-mediated phosphorylation in vivo. Each of the low-penetrant RB mutants exhibits marked enhancement of pocket protein binding when the cells are grown at reduced temperature. In contrast, in this temperature range, no change in binding activity is seen with WT RB, the 706F mutant, or the 707W mutant. We have demonstrated that many families with incomplete penetrance of familial retinoblastoma carry unstable, mutant RB alleles with temperature-sensitive pocket protein-binding activity. The variable frequency for tumor development in these families may result from reversible fluctuations in a threshold level of RB pocket-binding activity.
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Affiliation(s)
- G A Otterson
- Genetics Department, Medicine Branch, Division of Clinical Sciences, National Cancer Institute, Bethesda, MD, USA
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