RESUMO
Correctly identifying the true driver mutations in a patient's tumor is a major challenge in precision oncology. Most efforts address frequent mutations, leaving medium- and low-frequency variants mostly unaddressed. For TP53, this identification is crucial for both somatic and germline mutations, with the latter associated with the Li-Fraumeni syndrome (LFS), a multiorgan cancer predisposition. We present TP53_PROF (prediction of functionality), a gene specific machine learning model to predict the functional consequences of every possible missense mutation in TP53, integrating human cell- and yeast-based functional assays scores along with computational scores. Variants were labeled for the training set using well-defined criteria of prevalence in four cancer genomics databases. The model's predictions provided accuracy of 96.5%. They were validated experimentally, and were compared to population data, LFS datasets, ClinVar annotations and to TCGA survival data. Very high accuracy was shown through all methods of validation. TP53_PROF allows accurate classification of TP53 missense mutations applicable for clinical practice. Our gene specific approach integrated machine learning, highly reliable features and biological knowledge, to create an unprecedented, thoroughly validated and clinically oriented classification model. This approach currently addresses TP53 mutations and will be applied in the future to other important cancer genes.
Assuntos
Síndrome de Li-Fraumeni , Mutação de Sentido Incorreto , Predisposição Genética para Doença , Humanos , Síndrome de Li-Fraumeni/genética , Aprendizado de Máquina , Medicina de Precisão , Proteína Supressora de Tumor p53/genéticaRESUMO
Infrequent and rare genetic variants in the human population vastly outnumber common ones. Although they may contribute significantly to the genetic basis of a disease, these seldom-encountered variants may also be miss-identified as pathogenic if no correct references are available. Somatic and germline TP53 variants are associated with multiple neoplastic diseases, and thus have come to serve as a paradigm for genetic analyses in this setting. We searched 14 independent, globally distributed datasets and recovered TP53 SNPs from 202,767 cancer-free individuals. In our analyses, 19 new missense TP53 SNPs, including five novel variants specific to the Asian population, were recurrently identified in multiple datasets. Using a combination of in silico, functional, structural, and genetic approaches, we showed that none of these variants displayed loss of function compared to the normal TP53 gene. In addition, classification using ACMG criteria suggested that they are all benign. Considered together, our data reveal that the TP53 coding region shows far more polymorphism than previously thought and present high ethnic diversity. They furthermore underline the importance of correctly assessing novel variants in all variant-calling pipelines associated with genetic diagnoses for cancer.
Assuntos
Genes p53/genética , Mutação de Sentido Incorreto/genética , Neoplasias/genética , Polimorfismo de Nucleotídeo Único/genética , Proteína Supressora de Tumor p53/genética , HumanosRESUMO
The diagnosis of somatic and germline TP53 mutations in human tumors or in individuals prone to various types of cancer has now reached the clinic. To increase the accuracy of the prediction of TP53 variant pathogenicity, we gathered functional data from three independent large-scale saturation mutagenesis screening studies with experimental data for more than 10,000 TP53 variants performed in different settings (yeast or mammalian) and with different readouts (transcription, growth arrest or apoptosis). Correlation analysis and multidimensional scaling showed excellent agreement between all these variables. Furthermore, we found that some missense mutations localized in TP53 exons led to impaired TP53 splicing as shown by an analysis of the TP53 expression data from the cancer genome atlas. With the increasing availability of genomic, transcriptomic and proteomic data, it is essential to employ both protein and RNA prediction to accurately define variant pathogenicity.
Assuntos
Regulação Neoplásica da Expressão Gênica , Biblioteca Gênica , Mutação , Proteínas de Neoplasias/genética , Neoplasias/genética , Proteína Supressora de Tumor p53/genética , Processamento Alternativo , Animais , Apoptose/genética , Atlas como Assunto , Pontos de Checagem do Ciclo Celular/genética , Biologia Computacional/métodos , Éxons , Predisposição Genética para Doença , Humanos , Íntrons , Análise de Escalonamento Multidimensional , Mutagênese , Proteínas de Neoplasias/metabolismo , Neoplasias/metabolismo , Neoplasias/patologia , Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/metabolismo , Transcrição Gênica , Proteína Supressora de Tumor p53/deficiênciaRESUMO
The 1,000 genome project, the Exome Aggregation Consortium (ExAC) or the Genome Aggregation database (gnomAD) datasets, were developed to provide large-scale reference data of genetic variations for various populations to filter out common benign variants and identify rare variants of clinical importance based on their frequency in the human population. Using a TP53 repository of 80,000 cancer variants, as well as TP53 variants from multiple cancer genome projects, we have defined a set of certified oncogenic TP53 variants. This specific set has been independently validated by functional and in silico predictive analysis. Here we show that a significant number of these variants are included in gnomAD and ExAC. Most of them correspond to TP53 hotspot variants occurring as somatic and germline events in human cancer. Similarly, disease-associated variants for five other tumor suppressor genes, including BRCA1, BRCA2, APC, PTEN, and MLH1, have also been identified. This study demonstrates that germline TP53 variants in the human population are more frequent than previously thought. Furthermore, population databases such as gnomAD or ExAC must be used with caution and need to be annotated for the presence of oncogenic variants to improve their clinical utility.
Assuntos
Bases de Dados Genéticas , Predisposição Genética para Doença , Variação Genética , Neoplasias/genética , Proteína Supressora de Tumor p53/genética , Alelos , Estudos de Associação Genética , Genótipo , Mutação em Linhagem Germinativa , Humanos , Proteínas Supressoras de Tumor/genéticaRESUMO
Accurate annotation of genomic variants in human diseases is essential to allow personalized medicine. Assessment of somatic and germline TP53 alterations has now reached the clinic and is required in several circumstances such as the identification of the most effective cancer therapy for patients with chronic lymphocytic leukemia (CLL). Here, we present Seshat, a Web service for annotating TP53 information derived from sequencing data. A flexible framework allows the use of standard file formats such as Mutation Annotation Format (MAF) or Variant Call Format (VCF), as well as common TXT files. Seshat performs accurate variant annotations using the Human Genome Variation Society (HGVS) nomenclature and the stable TP53 genomic reference provided by the Locus Reference Genomic (LRG). In addition, using the 2017 release of the UMD_TP53 database, Seshat provides multiple statistical information for each TP53 variant including database frequency, functional activity, or pathogenicity. The information is delivered in standardized output tables that minimize errors and facilitate comparison of mutational data across studies. Seshat is a beneficial tool to interpret the ever-growing TP53 sequencing data generated by multiple sequencing platforms and it is freely available via the TP53 Website, http://p53.fr or directly at http://vps338341.ovh.net/.
Assuntos
Bases de Dados Genéticas , Variação Genética/genética , Software , Proteína Supressora de Tumor p53/genética , Biologia Computacional/tendências , Genômica/tendências , Sequenciamento de Nucleotídeos em Larga Escala , Humanos , Internet , Anotação de Sequência Molecular , MutaçãoRESUMO
Accurate assessment of TP53 gene status in sporadic tumors and in the germline of individuals at high risk of cancer due to Li-Fraumeni Syndrome (LFS) has important clinical implications for diagnosis, surveillance, and therapy. Genomic data from more than 20,000 cancer genomes provide a wealth of information on cancer gene alterations and have confirmed TP53 as the most commonly mutated gene in human cancer. Analysis of a database of 70,000 TP53 variants reveals that the two newly discovered exons of the gene, exons 9ß and 9γ, generated by alternative splicing, are the targets of inactivating mutation events in breast, liver, and head and neck tumors. Furthermore, germline rearrange-ments in intron 1 of TP53 are associated with LFS and are frequently observed in sporadic osteosarcoma. In this context of constantly growing genomic data, we discuss how screening strategies must be improved when assessing TP53 status in clinical samples. Finally, we discuss how TP53 alterations should be described by using accurate nomenclature to avoid confusion in scientific and clinical reports. Cancer Res; 77(6); 1250-60. ©2017 AACR.
Assuntos
Variação Genética/genética , Neoplasias/genética , Guias de Prática Clínica como Assunto/normas , Controle de Qualidade , Proteína Supressora de Tumor p53/genética , Humanos , Neoplasias/diagnóstico , Neoplasias/terapia , Estudos de Validação como AssuntoRESUMO
Tumor-derived cell lines play an important role in the investigation of tumor biology and genetics. Across a wide array of studies, they have been tools of choice for the discovery of important genes involved in cancer and for the analysis of the cellular pathways that are impaired by diverse oncogenic events. They are also invaluable for screening novel anticancer drugs. The TP53 protein is a major component of multiple pathways that regulate cellular response to various types of stress. Therefore, TP53 status affects the phenotype of tumor cell lines profoundly and must be carefully ascertained for any experimental project. In the present review, we use the 2014 release of the UMD TP53 database to show that TP53 status is still controversial for numerous cell lines, including some widely used lines from the NCI-60 panel. Our analysis clearly confirms that, despite numerous warnings, the misidentification of cell lines is still present as a silent and neglected issue, and that extreme care must be taken when determining the status of p53, because errors may lead to disastrous experimental interpretations. A novel compendium gathering the TP53 status of 2,500 cell lines has been made available (http://p53.fr). A stand-alone application can be used to browse the database and extract pertinent information on cell lines and associated TP53 mutations. It will be updated regularly to minimize any scientific issues associated with the use of misidentified cell lines (http://p53.fr).
Assuntos
Bases de Dados Genéticas , Mutação/genética , Neoplasias/genética , Proteína Supressora de Tumor p53/genética , Linhagem Celular Tumoral , Humanos , Internet , Neoplasias/patologia , SoftwareRESUMO
The architecture of TP53, the most frequently mutated gene in human cancer, is more complex than previously thought. Using TP53 variants as clinical biomarkers to predict response to treatment or patient outcome requires an unequivocal and standardized procedure toward a definitive strategy for the clinical evaluation of variants to provide maximum diagnostic sensitivity and specificity. An intronic promoter and two novel exons have been identified resulting in the expression of multiple transcripts and protein isoforms. These regions are additional targets for mutation events impairing the tumor suppressive activity of TP53. Reassessment of variants located in these regions is needed to refine their prognostic value in many malignancies. We recommend using the stable Locus Reference Genomic reference sequence for detailed and unequivocal reports and annotations of germ line and somatic alterations on all TP53 transcripts and protein isoforms according to the recommendations of the Human Genome Variation Society. This novel and comprehensive description framework will generate standardized data that are easy to understand, analyze, and exchange across various cancer variant databases. Based on the statistical analysis of more than 45,000 variants in the latest version of the UMD TP53 database, we also provide a classification of their functional effects ("pathogenicity").
Assuntos
Sequenciamento de Nucleotídeos em Larga Escala , Neoplasias/genética , Proteína Supressora de Tumor p53/genética , Bases de Dados Genéticas , Éxons , Genoma Humano , Humanos , Íntrons , Mutação , Neoplasias/patologia , Regiões Promotoras GenéticasRESUMO
More than 50% of human tumors carry TP53 gene mutations and in consequence more than 45,000 somatic and germline mutations have been gathered in the UMD TP53 database (http://p53.fr). Analyses of these mutations have been invaluable for bettering our knowledge on the structure-function relationships within the TP53 protein and the high degree of heterogeneity of the various TP53 mutants in human cancer. In this review, we discuss how with the release of the sequences of thousands of tumor genomes issued from high-throughput sequencing, the description of novel TP53 mutants is now reaching a plateau indicating that we are close to the full set of mutants that target the elusive tumor-suppressive activity of this protein. We performed an extensive and thorough analysis of the TP53 mutation database, focusing particularly on specific sets of mutations that were overlooked in the past because of their low frequencies, for example, synonymous mutations, splice mutations, or mutations-targeting residues subject to posttranslational modifications. We also discuss the evolution of the statistical methods used to differentiate TP53 passenger mutations and artifactual data from true mutations, a process vital to the release of an accurate TP53 mutation database that will in turn be an invaluable tool for both clinicians and researchers.
Assuntos
Bases de Dados Genéticas , Neoplasias/genética , Proteína Supressora de Tumor p53/genética , Análise Mutacional de DNA , Mutação em Linhagem Germinativa , Humanos , Neoplasias/patologiaRESUMO
A novel resource centre for TP53 mutations and mutants has been developed (http://p53.fr). TP53 gene dysfunction can be found in the majority of human cancer types. The potential use of TP53 mutation as a biomarker for clinical studies or exposome analysis has led to the publication of thousands of reports describing the TP53 gene status in >10,000 tumours. The UMD TP53 mutation database was created in 1990 and has been regularly updated. The 2012 release of the database has been carefully curated, and all suspicious reports have been eliminated. It is available either as a flat file that can be easily manipulated or as novel multi-platform analytical software that has been designed to analyse various aspects of TP53 mutations. Several tools to ascertain TP53 mutations are also available for download. We have developed TP53MULTLoad, a manually curated database providing comprehensive details on the properties of 2549 missense TP53 mutants. More than 100,000 entries have been arranged in 39 different activity fields, such as change of transactivation on various promoters, apoptosis or growth arrest. For several hot spot mutants, multiple gain of function activities are also included. The database can be easily browsed via a graphical user interface.
Assuntos
Bases de Dados de Ácidos Nucleicos , Genes p53 , Proteína Supressora de Tumor p53/genética , Humanos , Internet , Mutação , Neoplasias/genéticaRESUMO
Cancer mutation databases are expected to play central roles in personalized medicine by providing targets for drug development and biomarkers to tailor treatments to each patient. The accuracy of reported mutations is a critical issue that is commonly overlooked, which leads to mutation databases that include a sizable number of spurious mutations, either sequencing errors or passenger mutations. Here we report an analysis of the latest version of the TP53 mutation database, including 34,453 mutations. By using several data-driven methods on multiple independent quality criteria, we obtained a quality score for each report contributing to the database. This score can now be used to filter for high-confidence mutations and reports within the database. Sequencing the entire TP53 gene from various types of cancer using next-generation sequencing with ultradeep coverage validated our approach for curation. In summary, 9.7% of all collected studies, mostly comprising numerous tumors with multiple infrequent TP53 mutations, should be excluded when analyzing TP53 mutations. Thus, by combining statistical and experimental analyses, we provide a curated mutation database for TP53 mutations and a framework for mutation database analysis.
Assuntos
Bases de Dados Genéticas , Genes Supressores de Tumor , Genes p53 , Mutação , Neoplasias/genética , HumanosRESUMO
BACKGROUND: Basal cell carcinoma (BCC) is the most common form of skin cancer worldwide. Different treatment options exist. The efficacy of photodynamic therapy with methyl aminolevulinate (MAL-PDT) has been established in several randomized controlled trials (RCTs). Real life data can differ greatly from data derived from randomized controlled trials (RCTs). OBJECTIVES: To describe the results of a Belgian observational study concerning superficial BCC (sBCC) vis-a-vis clinical and health economic outcomes in order to evaluate the real-life practice of MAL-PDT. METHODS: This study was a prospective, single-arm, open study conducted at eight dermatological institutions during six months after the first MAL-PDT treatment. Eligible patients had to present with lesions, suitable for MAL-PDT according to Belgian reimbursement criteria. Resource use was collected during the study period. Clinical Response (CR) and Cosmetic Outcome (CO), as well as cost of care were evaluated. A subset analysis of patients with sBCC only was conducted. RESULTS: Ninety patients were identified for the analysis (mean age 65 years; 61% female). The mean number of lesions per patient was 1.6, mostly located on the face, the back and the chest. For the entire period, the mean number of visits to a dermatologist was 4 per patient including two MAL-PDT sessions. The average, cumulative amount of MAL used per treatment was 1,256 mg. Two patients experienced adverse events at the application site, none of them serious; all resolved completely. The CR rate was 89% at the end of the study. The CO was "excellent" or "good" in 96% of the patients. Total cost of care was Euro 289 ($414 U.S.) per patient. Cost per lesion was Euro 195 ($280 U.S.). CONCLUSION: The results from the real-life practice study confirm the efficacy found in prior, prospective randomized trials. About four visits and less than one tube of MAL are needed for the full treatment of sBCC in one patient.
Assuntos
Ácido Aminolevulínico/análogos & derivados , Carcinoma Basocelular/tratamento farmacológico , Fotoquimioterapia/métodos , Fármacos Fotossensibilizantes/uso terapêutico , Neoplasias Cutâneas/tratamento farmacológico , Idoso , Ácido Aminolevulínico/efeitos adversos , Ácido Aminolevulínico/economia , Ácido Aminolevulínico/uso terapêutico , Bélgica , Carcinoma Basocelular/economia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Fotoquimioterapia/efeitos adversos , Fotoquimioterapia/economia , Fármacos Fotossensibilizantes/efeitos adversos , Fármacos Fotossensibilizantes/economia , Estudos Prospectivos , Neoplasias Cutâneas/economia , Resultado do TratamentoRESUMO
Clinical trials have shown that photodynamic therapy using methyl aminolevulinate (MAL-PDT) is an effective treatment for actinic keratosis (AK), and nodular and superficial basal cell carcinoma (nBCC and sBCC) unsuitable for other available therapies. Economic evaluation models have shown that it is a cost effective intervention as well. The objectives of this prospective, observational, one arm study were (i) to verify in a real-life practice study the results obtained in previous clinical trials with MAL-PDT in the treatment of AK, nBCC and sBCC; (ii) to calculate the real-life cost of treatment and validate predictions from an economic evaluation model. Patients with AK and/or BCC were selected according to Belgian reimbursement criteria for treatment with MAL-PDT. Clinical response, cosmetic outcome and tolerability were assessed. MAL-PDT cost was calculated and compared to published model cost data. Data were collected from 247 patients (117 AK, 130 BCC). A complete clinical response was obtained for 83% of AK (85/102) and BCC (97/116) patients. A good or excellent cosmetic outcome was obtained for 95% of AK patients and 93% of BCC patients. Tolerability was good: only 2 patients withdrew for adverse events. Clinical results were similar to previous studies. Total cost of care per patient was euro 381 for AK, euro 318 for nBCC, and euro 298 for sBCC. Total cost per lesion was euro 58 for AK (identical to model prediction), euro 316 for nBCC and euro 178 for sBCC (both within 20% of model prediction). The clinical results of MAL-PDT in this real-life practice study confirm those demonstrated in previous clinical trials. Costs calculated from this study confirm predicted cost-effectiveness in the original model for MAL-PDT in the management of AK and BCC.