RESUMEN
BACKGROUND: Approximately 50 to 60% of patients with essential thrombocythemia or primary myelofibrosis carry a mutation in the Janus kinase 2 gene (JAK2), and an additional 5 to 10% have activating mutations in the thrombopoietin receptor gene (MPL). So far, no specific molecular marker has been identified in the remaining 30 to 45% of patients. METHODS: We performed whole-exome sequencing to identify somatically acquired mutations in six patients who had primary myelofibrosis without mutations in JAK2 or MPL. Resequencing of CALR, encoding calreticulin, was then performed in cohorts of patients with myeloid neoplasms. RESULTS: Somatic insertions or deletions in exon 9 of CALR were detected in all patients who underwent whole-exome sequencing. Resequencing in 1107 samples from patients with myeloproliferative neoplasms showed that CALR mutations were absent in polycythemia vera. In essential thrombocythemia and primary myelofibrosis, CALR mutations and JAK2 and MPL mutations were mutually exclusive. Among patients with essential thrombocythemia or primary myelofibrosis with nonmutated JAK2 or MPL, CALR mutations were detected in 67% of those with essential thrombocythemia and 88% of those with primary myelofibrosis. A total of 36 types of insertions or deletions were identified that all cause a frameshift to the same alternative reading frame and generate a novel C-terminal peptide in the mutant calreticulin. Overexpression of the most frequent CALR deletion caused cytokine-independent growth in vitro owing to the activation of signal transducer and activator of transcription 5 (STAT5) by means of an unknown mechanism. Patients with mutated CALR had a lower risk of thrombosis and longer overall survival than patients with mutated JAK2. CONCLUSIONS: Most patients with essential thrombocythemia or primary myelofibrosis that was not associated with a JAK2 or MPL alteration carried a somatic mutation in CALR. The clinical course in these patients was more indolent than that in patients with the JAK2 V617F mutation. (Funded by the MPN Research Foundation and Associazione Italiana per la Ricerca sul Cancro.).
Asunto(s)
Calreticulina/genética , Mutación , Mielofibrosis Primaria/genética , Trombocitemia Esencial/genética , Enfermedades de la Médula Ósea/genética , Exones , Humanos , Janus Quinasa 2/genética , Leucemia Mieloide/genética , Reacción en Cadena de la Polimerasa , Mielofibrosis Primaria/mortalidad , Modelos de Riesgos Proporcionales , Receptores de Trombopoyetina/genética , Análisis de Secuencia de ADN , Trombocitemia Esencial/complicaciones , Trombocitemia Esencial/mortalidad , Trombosis/etiologíaRESUMEN
Somatic mutations in the calreticulin (CALR) gene were recently discovered in patients with sporadic essential thrombocythemia (ET) and primary myelofibrosis (PMF) lacking JAK2 and MPL mutations. We studied CALR mutation status in familial cases of myeloproliferative neoplasm. In a cohort of 127 patients, CALR indels were identified in 6 of 55 (11%) subjects with ET and in 6 of 20 (30%) with PMF, whereas 52 cases of polycythemia vera had nonmutated CALR. All CALR mutations were somatic, found in granulocytes but not in T lymphocytes. Patients with CALR-mutated ET showed a higher platelet count (P = .017) and a lower cumulative incidence of thrombosis (P = .036) and of disease progression (P = .047) compared with those with JAK2 (V617F). In conclusion, a significant proportion of familial ET and PMF nonmutated for JAK2 carry a somatic mutation of CALR.
Asunto(s)
Calreticulina/genética , Mutación , Mielofibrosis Primaria/genética , Trombocitemia Esencial/genética , Análisis Mutacional de ADN , Exones/genética , Predisposición Genética a la Enfermedad , Genotipo , Humanos , Janus Quinasa 2/genética , Estimación de Kaplan-Meier , Linaje , Fenotipo , Mielofibrosis Primaria/mortalidad , Trombocitemia Esencial/mortalidadRESUMEN
Patients with essential thrombocythemia may carry JAK2 (V617F), an MPL substitution, or a calreticulin gene (CALR) mutation. We studied biologic and clinical features of essential thrombocythemia according to JAK2 or CALR mutation status and in relation to those of polycythemia vera. The mutant allele burden was lower in JAK2-mutated than in CALR-mutated essential thrombocythemia. Patients with JAK2 (V617F) were older, had a higher hemoglobin level and white blood cell count, and lower platelet count and serum erythropoietin than those with CALR mutation. Hematologic parameters of patients with JAK2-mutated essential thrombocythemia or polycythemia vera were related to the mutant allele burden. While no polycythemic transformation was observed in CALR-mutated patients, the cumulative risk was 29% at 15 years in those with JAK2-mutated essential thrombocythemia. There was no significant difference in myelofibrotic transformation between the 2 subtypes of essential thrombocythemia. Patients with JAK2-mutated essential thrombocythemia and those with polycythemia vera had a similar risk of thrombosis, which was twice that of patients with the CALR mutation. These observations are consistent with the notion that JAK2-mutated essential thrombocythemia and polycythemia vera represent different phenotypes of a single myeloproliferative neoplasm, whereas CALR-mutated essential thrombocythemia is a distinct disease entity.
Asunto(s)
Calreticulina/genética , Janus Quinasa 2/genética , Mutación , Trombocitemia Esencial/diagnóstico , Trombocitemia Esencial/genética , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Alelos , Transformación Celular Neoplásica/genética , Codón , Exones , Femenino , Granulocitos , Humanos , Masculino , Persona de Mediana Edad , Trastornos Mieloproliferativos/genética , Policitemia Vera/genética , Mielofibrosis Primaria/genética , Pronóstico , Receptores de Trombopoyetina/genética , Trombocitemia Esencial/mortalidad , Trombosis/genética , Adulto JovenRESUMEN
Fifty-one polycythemia vera (PV) patients were enrolled in the phase I/II clinical study PEGINVERA to receive a new formulation of pegylated interferon alpha (peg-proline-IFNα-2b, AOP2014/P1101). Peg-proline-IFNα-2b treatment led to high response rates on both hematologic and molecular levels. Hematologic and molecular responses were achieved for 46 and 18 patients (90 and 35% of the whole cohort), respectively. Although interferon alpha (IFNα) is known to be an effective antineoplastic therapy for a long time, it is currently not well understood which genetic alterations influence therapeutic outcomes. Apart from somatic changes in specific genes, large chromosomal aberrations could impact responses to IFNα. Therefore, we evaluated the interplay of cytogenetic changes and IFNα responses in the PEGINVERA cohort. We performed high-resolution SNP microarrays to analyze chromosomal aberrations prior and during peg-proline-IFNα-2b therapy. Similar numbers and types of chromosomal aberrations in responding and non-responding patients were observed, suggesting that peg-proline-IFNα-2b responses are achieved independently of chromosomal aberrations. Furthermore, complete cytogenetic remissions were accomplished in three patients, of which two showed more than one chromosomal aberration. These results imply that peg-proline-IFNα-2b therapy is an effective drug for PV patients, possibly including patients with complex cytogenetic changes.
Asunto(s)
Antineoplásicos/uso terapéutico , Aberraciones Cromosómicas , Interferón-alfa/uso terapéutico , Janus Quinasa 2/genética , Policitemia Vera/tratamiento farmacológico , Polietilenglicoles/uso terapéutico , Polimorfismo de Nucleótido Simple , Adulto , Anciano , Anciano de 80 o más Años , Antineoplásicos/administración & dosificación , Antineoplásicos/efectos adversos , Aberraciones Cromosómicas/efectos de los fármacos , Estudios de Cohortes , ADN/genética , Femenino , Frecuencia de los Genes/efectos de los fármacos , Estudio de Asociación del Genoma Completo , Humanos , Interferón alfa-2 , Interferón-alfa/administración & dosificación , Interferón-alfa/efectos adversos , Masculino , Persona de Mediana Edad , Terapia Molecular Dirigida , Policitemia Vera/sangre , Policitemia Vera/genética , Polietilenglicoles/administración & dosificación , Polietilenglicoles/efectos adversos , Proteínas Recombinantes/administración & dosificación , Proteínas Recombinantes/efectos adversos , Proteínas Recombinantes/uso terapéutico , Resultado del TratamientoRESUMEN
The extracellular matrix protein Laminin B1 (LamB1) regulates tumor cell migration and invasion. Carcinoma cells acquire invasive properties by epithelial to mesenchymal transition (EMT), which is a fundamental step in dissemination of metastatic cells from the primary tumor. Recently, we showed that enhanced translation of LamB1 upon EMT of malignant hepatocytes is mediated by an internal ribosome entry site (IRES). We demonstrated that the IRES transacting factor La binds the minimal IRES motif and positively modulates IRES activity of LamB1. Here, we show that platelet-derived growth factor (PDGF) enhances IRES activity of LamB1 by the increasing cytoplasmic localization of La during EMT. Accordingly, cells expressing dominant negative PDGF receptor display reduced cytoplasmic accumulation of La and show no elevation of IRES activity or endogenous LamB1 levels after stimulation with PDGF. Furthermore, La-mediated regulation of LamB1 IRES activity predominantly depends on MAPK/ERK signaling downstream of PDGF. Notably, LamB1 expression is not significantly downregulated by the impairment of the translation initiation factor eIF4E. In vivo, knockdown of La associated with decreased LamB1 expression and reduced tumor growth. Together, these data suggest that PDGF is required for the cytoplasmic accumulation of La that triggers IRES-dependent translation of LamB1 during EMT.
Asunto(s)
Regiones no Traducidas 5' , Transición Epitelial-Mesenquimal/genética , Laminina/genética , Factor de Crecimiento Derivado de Plaquetas/farmacología , Biosíntesis de Proteínas , Proteínas de Unión al ARN/metabolismo , Animales , Células Cultivadas , Citoplasma/efectos de los fármacos , Citoplasma/metabolismo , Laminina/biosíntesis , Sistema de Señalización de MAP Quinasas , Ratones , Ratones SCID , Proteínas Quinasas Activadas por Mitógenos/metabolismo , Fosfatidilinositol 3-Quinasas/metabolismo , Biosíntesis de Proteínas/efectos de los fármacos , Transducción de SeñalRESUMEN
The clonal blood disorders polycythemia vera, essential thrombocythemia and primary myelofibrosis belong to the BCR-ABL1-negative myeloproliferative neoplasms and are specified by increased production of terminally differentiated myeloid cells. Clonal evolution, disease initiation and progression are influenced by genetic alterations, often affecting cytokine signaling and gene expression. This review outlines somatic changes discovered in myeloproliferative neoplasms and how these genetic aberrations influence the pathogenesis of myeloproliferative neoplasms. Furthermore, genetic responses to drug treatments in myeloproliferative neoplasms are discussed.