RESUMEN
Researchers worldwide with information about the Kirsten ras (Ki-ras) tumour genotype and outcome of patients with colorectal cancer were invited to provide that data in a schematized format for inclusion in a collaborative database called RASCAL (The Kirsten ras in-colorectal-cancer collaborative group). Our results from 2721 such patients have been presented previously and for the first time in any common cancer, showed conclusively that different gene mutations have different impacts on outcome, even when the mutations occur at the same site on the genome. To explore the effect of Ki-ras mutations at different stages of colorectal cancer, more patients were recruited to the database, which was reanalysed when information on 4268 patients from 42 centres in 21 countries had been entered. After predetermined exclusion criteria were applied, data on 3439 patients were entered into a multivariate analysis. This found that of the 12 possible mutations on codons 12 and 13 of Kirsten ras, only one mutation on codon 12, glycine to valine, found in 8.6% of all patients, had a statistically significant impact on failure-free survival (P = 0.004, HR 1.3) and overall survival (P = 0.008, HR 1.29). This mutation appeared to have a greater impact on outcome in Dukes' C cancers (failure-free survival, P = 0.008, HR 1.5; overall survival P = 0.02, HR 1.45) than in Dukes' B tumours (failure-free survival, P = 0.46, HR 1.12; overall survival P = 0.36, HR 1.15). Ki-ras mutations may occur early in the development of pre-cancerous adenomas in the colon and rectum. However, this collaborative study suggests that not only is the presence of a codon 12 glycine to valine mutation important for cancer progression but also that it may predispose to more aggressive biological behaviour in patients with advanced colorectal cancer.
Asunto(s)
Neoplasias Colorrectales/genética , Bases de Datos Factuales , Genes ras/genética , Mutación Puntual , Sistema de Registros , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Codón/genética , Neoplasias Colorrectales/mortalidad , Supervivencia sin Enfermedad , Femenino , Genotipo , Humanos , Masculino , Persona de Mediana Edad , Análisis Multivariante , Mutación Missense , Estadificación de Neoplasias , Modelos de Riesgos Proporcionales , Análisis de Supervivencia , Valina/genéticaRESUMEN
Neoplastic transformation is increasingly understood in terms of evolutionary mechanisms, and it is now widely accepted that tumor progression involves natural selection of genetic variants occurring in the somatic environment. Here we give a review of data that substantiate this Darwinian view to tumorigenesis, with particular emphasis on recent advances related to colorectal cancer. We specifically focus on the controversies related to genomic instability and DNA methylation, and present a model, which interrelates these phenomena to the basic evolutionary concept of biology.
Asunto(s)
Transformación Celular Neoplásica/genética , Aberraciones Cromosómicas/genética , Neoplasias Colorrectales/genética , Neoplasias Colorrectales/patología , Metilación de ADN , Selección Genética , Evolución Molecular , Humanos , Modelos Genéticos , Mutagénesis/genética , Lesiones Precancerosas/genética , Lesiones Precancerosas/patologíaAsunto(s)
Neoplasias Colorrectales/genética , Neoplasias Colorrectales/fisiopatología , Proteínas Proto-Oncogénicas c-bcl-2 , Selección Genética , Carcinógenos , Ciclo Celular , Cromosomas Humanos , Neoplasias Colorrectales/patología , Metilación de ADN , Reparación del ADN , Evolución Molecular , Humanos , Repeticiones de Microsatélite , Mutación Puntual , Pronóstico , Proteínas Proto-Oncogénicas/genética , Proteína X Asociada a bcl-2RESUMEN
BACKGROUND: Colorectal carcinogenesis is regarded as a multistep process involving several genetic alterations, with mutation in the K-ras gene in about half of the tumours. We aimed at clarifying the role of this genetic alteration related to survival and clinicopathologic variables. METHODS: One hundred large-bowel carcinomas operated on between 1978 and 1982 were studied for the presence of point mutations in codons 12 and 13 of the K-ras gene, using enriched polymerase chain reaction amplification, restriction fragment length polymorphism analysis, and direct sequencing. RESULTS: Forty mutations were found (40%): 31 in codon 12 and 9 in codon 13, 7 different types. There was no relationship between tumours with and without K-ras mutations with regard to Dukes' stages, age or sex of the patient, tumour localization, histologic grade, DNA ploidy pattern, HLA-DR staining pattern, or survival. Samples from 5 different localizations in 7 carcinomas showed identical K-ras mutation pattern, as did 19 recurrences/ metastases originating from 11 carcinomas. CONCLUSIONS: When present, the primary tumour shows homogeneous distribution of K-ras mutation, and the mutation follows the carcinoma in the secondary deposit, regardless of lymphogenous or hematogenous spread. The presence of K-ras mutation does not seem to have prognostic significance for the patient, and the precise nucleotide change is furthermore not predictive of tumour behaviour.
Asunto(s)
Neoplasias Colorrectales/genética , Neoplasias Colorrectales/mortalidad , Genes ras , Mutación Puntual , Adulto , Anciano , Anciano de 80 o más Años , Neoplasias Colorrectales/patología , Femenino , Estudios de Seguimiento , Humanos , Masculino , Persona de Mediana Edad , Recurrencia Local de Neoplasia/genética , Estadificación de Neoplasias , Pronóstico , Factores de Riesgo , Análisis de SupervivenciaRESUMEN
Mutations in the k-ras and TP53 genes, as well as microsatellite instability (MIN), are frequent genetic alterations in colorectal carcinomas and represent 3 different mechanisms in the carcinogenic process. Both the incidence of colorectal cancer and the frequency of genetic alterations in such tumours have been related to different clinico-pathological variables, including age and gender of the patient and location of the tumour. A number of studies have also reported associations between different types of genetic alterations. We therefore wanted to explore the relationship between these genetic and clinico-pathological variables using multivariate analysis on material from 282 colorectal carcinomas. Three logistic regression models were constructed: 1) the presence of K-ras mutations was dependent on MIN and age and gender of patient, with an especially low frequency among younger males and in tumours with MIN (overall p = 0.0003); 2) the presence of TP53 mutations was only dependent on tumour location, with a positive association to cancers occurring distally (p = 0.002); and 3) the presence of MIN was dependent on age, gender and K-ras and TP53 mutations, as well as on tumour location. MIN was most frequent among younger male and older female patients, was rare in tumours with K-ras or TP53 mutations and was found almost exclusively in the proximal colon (overall p < 0.0001). Our data confirm that different genetic pathways to colorectal cancer dominate in the proximal and distal segments of the bowel and suggest that the K-ras- and MIN-dependent pathways are influenced by different sex-related factors.
Asunto(s)
Neoplasias Colorrectales/genética , Adulto , Anciano , Anciano de 80 o más Años , Neoplasias Colorrectales/patología , ADN de Neoplasias/genética , Femenino , Genes p53 , Genes ras , Humanos , Masculino , Repeticiones de Microsatélite , Persona de Mediana Edad , Mutación , Análisis de Regresión , Factores SexualesRESUMEN
A total of 72 sporadic colorectal adenomas in 56 patients were studied for the presence of point mutations in codons 12 and 13 of the K-ras gene and for HLA-DR antigen expression related to clinicopathological variables. Forty K-ras mutations in 39 adenomas were found (54%): 31 (77%) in codon 12 and nine (23%) in codon 13. There was a strong relationship between the incidence of K-ras mutations and adenoma type, degree of dysplasia and sex. The highest frequency of K-ras mutations was seen in large adenomas of the villous type with high-grade dysplasia. Fourteen out of 15 adenomas obtained from 14 women above 65 years of age carried mutations. HLA-DR positivity was found in 38% of the adenomas, large tumours and those with high-grade dysplasia having the strongest staining. Coexpression of K-ras mutations and HLA-DR was found significantly more frequently in large and highly dysplastic adenomas, although two-way analysis of variance showing size and grade of dysplasia to be the most important variable. None of the adenomas with low-grade dysplasia showed both K-ras mutation and HLA-DR positivity (P = 0.004). K-ras mutation is recognised as an early event in colorectal carcinogenesis. The mutation might give rise to peptides that may be presented on the tumour cell surface by class II molecules, and thereby induce immune responses against neoplastic cells.
Asunto(s)
Adenoma/química , Adenoma/genética , Neoplasias Colorrectales/química , Neoplasias Colorrectales/genética , Genes ras , Antígenos HLA-DR/análisis , Mutación , Adenoma/patología , Adulto , Anciano , Anciano de 80 o más Años , Secuencia de Bases , Neoplasias Colorrectales/patología , Epitelio/química , Epitelio/patología , Epitelio/fisiología , Femenino , Humanos , Masculino , Persona de Mediana Edad , Datos de Secuencia Molecular , Regulación hacia Arriba/fisiologíaRESUMEN
In a pilot I/II study we have tested synthetic ras peptides used as a cancer vaccine in 5 patients with advanced pancreatic carcinoma. The treatment principle used was based on loading professional antigen-presenting cells (APCs) from peripheral blood with a synthetic ras peptide corresponding to the ras mutation found in tumour tissue from the patient. Peptide loading was performed ex vivo and the next day APCs were re-injected into the patients after washing to remove unbound peptide. Patients were vaccinated in the first and second week and thereafter every 4-6 weeks. In 2 of the 5 patients treated, an immune response against the immunising ras peptide could be induced. None of the patients showed evidence of a T-cell response against any of the ras peptides before vaccination. The treatment was well tolerated and could be repeated multiple times in the same patient. Side effects were not observed even if an immunological response against the ras peptide was evident. We conclude that ras peptide vaccination according to the present protocol is safe and may result in a potentially beneficial immune response even in patients with advanced malignant disease.
Asunto(s)
Neoplasias Pancreáticas/terapia , Vacunas Sintéticas/inmunología , Proteínas ras/inmunología , Adulto , Anciano , Secuencia de Aminoácidos , Femenino , Humanos , Masculino , Persona de Mediana Edad , Datos de Secuencia Molecular , Neoplasias Pancreáticas/inmunología , Proyectos Piloto , VacunaciónRESUMEN
Mutations in codon 12 of K-RAS are frequently found in pancreatic adenocarcinomas. T-cell responses specific for individual RAS mutations can be elicited in vitro by stimulation of peripheral blood mononuclear cells with synthetic peptides. Mutant ras peptides are therefore a candidate vaccine for specific immunotherapy in pancreatic carcinoma patients. When vaccinated with a synthetic ras peptide representing the K-RAS mutation in their tumours, a transient ras-specific T-cell response was induced in two of five patients treated. The vaccination protocol involved multiple infusions of large amounts of peptide-pulsed antigen-presenting-cells obtained by leucapheresis. These results indicate that specific T-cell responses against mutations uniquely harboured in tumour cells can be induced in cancer patients by vaccination.
Asunto(s)
Adenocarcinoma/terapia , Inmunoterapia/métodos , Neoplasias Pancreáticas/terapia , Linfocitos T/inmunología , Proteínas ras/inmunología , Adenocarcinoma/genética , Células Presentadoras de Antígenos/inmunología , Humanos , Leucaféresis , Mutación , Neoplasias Pancreáticas/genética , Proteínas ras/genéticaRESUMEN
We have characterized and described in detail 2 CD4+ T-lymphocyte clones (TLC) from a colonic cancer patient. These TLC specifically recognize a K-ras-derived peptide carrying the 13Asp mutation commonly found in adenocarcinomas of the colon. The TLC were independently derived, as they carried 2 different T-cell receptors. The TLC recognized partly overlapping epitopes within the 13Asp peptide, presented by HLA-DQ7 molecules, suggesting that this molecule might confer some protective immunity against the mutation. On the basis of analysis of 251 colonic carcinomas, the presence of HLA-DQ7 did not seem to protect against the establishment of carcinomas carrying the 13Asp mutation, since the frequency of the DQ7 haplotype was not decreased among patients having this mutation. A modifying effect of DQ7 on the development of carcinomas with a 13Asp mutation was, however, observed, resulting in fewer tumours reaching advanced Dukes stages when DQ7 was present.
Asunto(s)
Linfocitos T CD4-Positivos/inmunología , Neoplasias Colorrectales/genética , Genes ras , Antígenos HLA-DQ , Mutación , Secuencia de Aminoácidos , Secuencia Conservada , Femenino , Humanos , Persona de Mediana Edad , Datos de Secuencia MolecularRESUMEN
DNA from 251 primary tumours obtained from 123 male and 125 female Norwegian patients with colorectal carcinoma was analysed for the presence of K-ras point mutations at codons 12 and 13. Mutations were found in 99 (39%) of the samples. The frequency of K-ras mutations was significantly related to age and sex of the patients, and to the location of the tumours (overall: P = 0.008). K-ras mutations were much less frequent in colonic tumours from male than female patients at younger ages (< 40 years, odds ratio < 0.014). The low frequency might indicate that a different, ras-independent, pathway to neoplasia is dominating in the colon of younger males. In contrast, older men had more mutations than older women (e.g. 90 years, odds ratio = 5.8). An inverse but less pronounced relationship was seen for rectal tumours. The type of mutation was found to be associated to sex of patient and location of tumour. G-->C transversions accounted for 35% of the mutations in rectal tumours from females, in contrast to only 2.5% in the rest of the material (P = 0.0005). This may indicate that there are specific carcinogens acting in this location.
Asunto(s)
Neoplasias Colorrectales/genética , Genes ras/genética , Mutación Puntual/genética , Adulto , Anciano , Anciano de 80 o más Años , Secuencia de Bases , Femenino , Humanos , Masculino , Persona de Mediana Edad , Datos de Secuencia MolecularRESUMEN
Peptides derived from mutated ras are immunogenic in mice and humans, and represent a group of specific tumor antigens that are potential targets for immunotherapy. T-cell responses against mutant p21 ras can be initiated in vitro by repeated stimulation of peripheral-blood mononuclear cells with mutant ras-derived peptides. Patients with tumors commonly harbouring ras mutations may therefore show evidence of in vivo reactivity against such mutations. Peripheral-blood mononuclear cells from 10 patients with colorectal adenocarcinoma were screened for reactivity against synthetic ras-derived peptides corresponding to the most commonly found mutations in this type of cancer. In one patient, T-cell reactivity against the 1-25,13Gly-->Asp peptide was detected. From this patient, both CD4+ and CD8+ T-cell clones specific for the 1-25,13Gly-->Asp mutation could be raised. We were not, however, able to detect the corresponding mutation in the cancer. The 13Gly-->Asp mutation in the ras oncogene is frequent and constitutes 9 to 27% of all K ras mutations found in biopsies from patients with colorectal carcinomas. Our study demonstrates a mutant ras-specific T-cell response of both the CD4+ and the CD8+ phenotype in a cancer patient. We speculate that in this patient a specific T-cell response resulted in eradication of tumor cells harboring the 13Gly-->Asp mutation.
Asunto(s)
Adenocarcinoma/inmunología , Ácido Aspártico/inmunología , Linfocitos T CD4-Positivos/inmunología , Antígenos CD8/inmunología , Neoplasias Colorrectales/inmunología , Glicina/inmunología , Mutación/inmunología , Péptidos/inmunología , Proteínas Proto-Oncogénicas p21(ras)/inmunología , Linfocitos T/inmunología , Adenocarcinoma/genética , Secuencia de Aminoácidos , Ácido Aspártico/genética , Antígenos CD8/genética , Células Cultivadas/inmunología , Neoplasias Colorrectales/genética , Femenino , Amplificación de Genes , Genes ras/genética , Genes ras/inmunología , Glicina/genética , Humanos , Persona de Mediana Edad , Datos de Secuencia Molecular , Mutación/genética , Péptidos/genética , Fenotipo , Proteínas Proto-Oncogénicas p21(ras)/genéticaRESUMEN
Det norske Veritas has been engaged by the Ministry of Health and Social Affairs to establish measures to improve safety and efficiency in the utilization of medical equipment in Norwegian hospitals. A major effort in this respect is to help the hospitals to implement a quality system for medical equipment. This quality system is to be based on the Veritas produced Model for a Quality Manual for Medical Equipment. Det norske Veritas offers an information video and a course as a help to hospitals in implementing the system. Other remedies so far are a Standard Agreement for Purchase and Sale of Medical Equipment and, as a result of nationwide committee work, Procedure Models for Gas Anaesthesia Equipment.