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1.
J Clin Oncol ; 37(31): 2857-2865, 2019 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-31513482

RESUMO

PURPOSE: Off-label use of vemurafenib (VMF) to treat BRAFV600E mutation-positive, refractory, childhood Langerhans cell histiocytosis (LCH) was evaluated. PATIENTS AND METHODS: Fifty-four patients from 12 countries took VMF 20 mg/kg/d. They were classified according to risk organ involvement: liver, spleen, and/or blood cytopenia. The main evaluation criteria were adverse events (Common Terminology Criteria for Adverse Events [version 4.3]) and therapeutic responses according to Disease Activity Score. RESULTS: LCH extent was distributed as follows: 44 with positive and 10 with negative risk organ involvement. Median age at diagnosis was 0.9 years (range, 0.1 to 6.5 years). Median age at VMF initiation was 1.8 years (range, 0.18 to 14 years), with a median follow-up of 22 months (range, 4.3 to 57 months), whereas median treatment duration was 13.9 months (for 855 patient-months). At 8 weeks, 38 complete responses and 16 partial responses had been achieved, with the median Disease Activity Score decreasing from 7 at diagnosis to 0 (P < .001). Skin rash, the most frequent adverse event, affected 74% of patients. No secondary skin cancer was observed. Therapeutic plasma VMF concentrations (range, 10 to 20 mg/L) seemed to be safe and effective. VMF discontinuation for 30 patients led to 24 LCH reactivations. The blood BRAFV600E allele load, assessed as circulating cell-free DNA, decreased after starting VMF but remained positive (median, 3.6% at diagnosis, and 1.6% during VMF treatment; P < .001) and was associated with a higher risk of reactivation at VMF discontinuation. None of the various empirical therapies (hematopoietic stem-cell transplantation, cladribine and cytarabine, anti-MEK agent, vinblastine, etc) used for maintenance could eradicate the BRAFV600E clone. CONCLUSION: VMF seemed safe and effective in children with refractory BRAFV600E-positive LCH. Additional studies are needed to find effective maintenance therapy approaches.

5.
Br J Haematol ; 183(4): 608-617, 2018 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-30421536

RESUMO

Neurodegenerative (ND) complications in Langerhans cell histiocytosis (LCH) are a late-onset but dramatic sequelae for which incidence and risk factors are not well defined. Based on a national prospective registry of paediatric LCH patients, we determined the incidence rate of clinical ND LCH (cND-LCH) and analysed risk factors, taking into account disease extent and molecular characteristics. Among 1897 LCH patients, 36 (1·9%) were diagnosed with a cND-LCH. The 10-year cumulative incidence of cND-LCH was 4·1%. cND-LCH typically affected patients previously treated for a multisystem, risk organ-negative LCH, represented in 69·4% of cND-LCH cases. Pituitary gland, skin and base skull/orbit bone lesions were more frequent (P < 0·001) in cND-LCH patients compared to those without cND-LCH (respectively 86·1% vs. 12·2%, 75·0% vs. 34·2%, and 63·9% vs. 28·4%). The 'cND susceptible patients' (n = 671) i.e., children who had experienced LCH disease with pituitary or skull base or orbit bone involvement, had a 10-year cND risk of 7·8% vs. 0% for patients who did not meet these criteria. Finally, BRAFV 600E status added important information among these cND susceptible patients, with the 10-year cND risk of 33·1% if a BRAFV 600E mutation was present compared to 2·9% if it was absent (P = 0·002).

7.
Am J Dermatopathol ; 2018 Sep 24.
Artigo em Inglês | MEDLINE | ID: mdl-30252693

RESUMO

Langerhans cell (LC) histiocytoma is a neonatal tumor that often consists of a single, ulcerated nodule. Systemic involvement is rare, and LC histiocytoma is considered to be a variant of congenital, self-healing LC histiocytosis (also referred to as Hashimoto-Pritzker disease). In view of its low prevalence, LC histiocytoma is not always diagnosed in a clinical examination and requires histological confirmation. Furthermore, the histological and molecular features of LC histiocytoma have not been well characterized. Here, we report on 6 cases of this rare disease and review the corresponding literature. LC histiocytoma differs from classical self-healing LC histiocytosis with regard to the pathological features; we found that LC histiocytoma was associated with massive infiltration by histiocytes of various sizes and shapes (although often large) throughout the dermis and the superficial subcutis. Epidermotropism was rare, mitotic figures were not inconspicuous, and necrotic or calcified areas were often present. Immunohistochemical assessment revealed a mixture of different types of histiocytes (with CD1a CD207, CD1a CD207, and CD1a CD207 CD163 cells). Genetic testing was performed in 5 cases; it revealed a BRAF mutation (p.V600E and p.485_490delinsF) in 2 cases, a HRAS mutation (p.T58I) in 1 case, a combination of 2 PTEN mutations in another case (p.I224M and p. R234W), and no mutations in the fifth case. All the lesions regressed spontaneously, and none recurred during follow-up.

8.
Oncoimmunology ; 7(8): e1452581, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30221046

RESUMO

Immune checkpoint inhibitors, as nivolumab, are used in advanced non-small cell lung cancer (NSCLC). However, no associated biomarker is validated in clinical practice with this drug. We investigated herein immune-related blood markers in patients with advanced NSCLC treated with nivolumab. Plasma of 43 consecutive patients were prospectively collected at time of the diagnosis of cancer, at the initiation of nivolumab and at the first tumour evaluation (2 months). Concentrations of PD-L1 (sPD-L1), soluble PD-L2 (sPD-L2), Interleukine-2 (sIl-2), Interferon-gamma (sIFN-γ), and Granzyme B (sGranB) were quantified by ELISA. Cell free RNA was quantified by Reverse Transcriptase -PCR), and plasmatic microRNAs (miRNAs) were evaluated by targeted sequencing. Expression of PD-L1 on tumour biopsies was performed by immunohistochemistry using E13LN. High sPD-L1 at 2 months and increase of sPD-L1 concentrations were associated with poor response and absence of clinical benefit (nivolumab treatment less than 6 months). The variation of sPD-L1 concentrations were confirmed by RNA quantification. sPD-L1 concentrations were not correlated with PD-L1 expression on corresponding tumour samples. Low sGranB at nivolumab initiation was also associated with poor response. High sPD-L1 and low sGranB were associated with poor progression-free survival (PFS) and overall survival (OS). Low sPD-L2, low sIl-2 and high sIFN-γ were associated with grade 3-4 toxicities. Finally, miRNA screening showed that patients with clinical benefit (n = 9) had down-expression of miRNA-320b and -375 compared to patients with early progression at 2 months (n = 9). In conclusion, our results highlight the interest of circulating biomarkers in patients treated with nivolumab.

9.
Cancer Invest ; 36(6): 338-348, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30136875

RESUMO

Aneuploidy is a common feature of cancer cells and may contribute to cellular transformation and cancer development. In this study, we found that significant down-regulation of CDKN2A, CHEK2, CDCA8, TP53BP1, and CCNDBP1 led to chromosome imbalances in two diploid non-immortalized human cell lines; however, only CDKN2A inhibition enhanced cell proliferation and additionally up-regulated three cell cycle control genes: CDCA8, AURKA, and CCND. These results confirm that CDKN2A is a tumor suppressor gene driving human cancer development by inducing cell aneuploidy and cell cycle up-regulation.


Assuntos
Proliferação de Células/genética , Transformação Celular Neoplásica/genética , Inibidor de Quinase Dependente de Ciclina p18/genética , Genes Supressores de Tumor , Aneuploidia , Aurora Quinase A/genética , Proteínas de Ciclo Celular/genética , Linhagem Celular Tumoral , Transformação Celular Neoplásica/patologia , Quinase do Ponto de Checagem 2/genética , Regulação Neoplásica da Expressão Gênica , Humanos , Proteína 1 de Ligação à Proteína Supressora de Tumor p53/genética
11.
Blood ; 130(8): 1007-1013, 2017 08 24.
Artigo em Inglês | MEDLINE | ID: mdl-28679734

RESUMO

Erdheim-Chester disease (ECD) is a rare non-Langerhans cell histiocytosis that most commonly affects adults and is driven by a high frequency of mutations in BRAF, MAP2K1, and kinases promoting MAPK signaling. Because of the relative rarity of ECD, key clinical features of the disease may not be well defined. Across a multi-institutional cohort of 189 patients with ECD and ECD overlapping with Langerhans cell histiocytosis (so-called mixed histiocytosis [MH]), we identified an unexpected and heretofore undescribed frequent occurrence of myeloid neoplasms among patients with ECD and MH. Some 10.1% (19/189) of patients with ECD have an overlapping myeloid neoplasm, most commonly occurring as a myeloproliferative neoplasm (MPN), myelodysplastic syndrome (MDS), or mixed MDS/MPN overlap syndrome (including chronic myelomonocytic leukemia). Consistent with this, molecular analysis frequently detected hallmark driver mutations of myeloid neoplasms (such as JAK2V617F and CALR mutations) coexisting with those characteristic of histiocytosis (such as BRAFV600E and MAP2K1 mutations). Histiocytosis patients diagnosed with a concomitant myeloid malignancy were significantly older at diagnosis and more commonly presented with MH than those without a myeloid malignancy. In some cases, the presence of distinct kinase mutations in the histiocytosis and myeloid neoplasm resulted in discordant and adverse responses to kinase-directed targeted therapies. These data highlight the clinical importance of evaluating adults with histiocytosis for a concomitant myeloid neoplasm.


Assuntos
Neoplasias da Medula Óssea/complicações , Neoplasias da Medula Óssea/epidemiologia , Histiocitose de Células não Langerhans/complicações , Adulto , Idoso , Doença de Erdheim-Chester/complicações , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Terapia de Alvo Molecular , Prevalência
12.
Mol Cancer ; 16(1): 115, 2017 07 06.
Artigo em Inglês | MEDLINE | ID: mdl-28679432

RESUMO

Langerhans cell histiocytosis (LCH) is an inflammatory myeloid neoplasia with constitutive activation of the MAPKinase RAS-RAF-MEK-ERK cell signaling pathway. We analyzed 9 LCH cases without BRAF V600 and MAP2K1 mutations by whole exome sequencing. We identified a new somatic BRAF splicing mutation in 2 cases. Both cases were childhood single system (SS) LCH cases, with self-healing outcome of the bone lesions. This mutant consisted in a 9 base pair duplication (c.1511_1517 + 2 duplication), encoding for a predicted mutant protein with insertion of 3 amino acids (p.Arg506_Lys507insLeuLeuArg) in the N-terminal lobe of the kinase domain of BRAF. Transient expression of the c.1511_1517 + 2dup BRAF mutant in HEK293 cells enhanced MAPKinase pathway activation, and was not inhibited by vemurafenib but was inhibited by PLX8394, a second-generation BRAF inhibitor able to inhibit signaling of BRAF monomers and dimers. Future LCH molecular screening panel should include this new mutation to better define its prevalence in LCH and its restriction to autoregressive bone SS LCH.


Assuntos
Histiocitose de Células de Langerhans/genética , Mutação/genética , Proteínas Proto-Oncogênicas B-raf/genética , Processamento de RNA/genética , Adolescente , Sequência de Bases , Criança , Pré-Escolar , Éxons/genética , Feminino , Duplicação Gênica , Histiocitose de Células de Langerhans/tratamento farmacológico , Humanos , Lactente , Masculino , Proteínas Quinases Ativadas por Mitógeno/antagonistas & inibidores , Proteínas Quinases Ativadas por Mitógeno/metabolismo , Inibidores de Proteínas Quinases/uso terapêutico
13.
BMC Dermatol ; 17(1): 9, 2017 07 01.
Artigo em Inglês | MEDLINE | ID: mdl-28668077

RESUMO

BACKGROUND: Somatic mutations of BRAF or NRAS activating the MAP kinase cell signaling pathway are present in 70% of cutaneous melanomas. The mutant allele frequency of BRAF V600E (M%BRAF) was recently shown to be highly heterogeneous in melanomas. The present study focuses on the NRAS Q61 mutant allele frequency (M%NRAS). METHODS: Retrospective quantitative analyze of 104 NRAS mutated melanomas was performed using pyrosequencing. Mechanisms of M%NRAS imbalance were studied by fluorescence in situ hybridization (FISH) and microsatellite analysis. RESULTS: M%NRAS was increased in 27.9% of cases. FISH revealed that chromosome 1 instability was the predominant mechanism of M%NRAS increase, with chromosome 1 polysomy observed in 28.6% of cases and intra-tumor cellular heterogeneity with copy number variations of chromosome 1/NRAS in 23.8%. Acquired copy-neutral loss of heterozygosity (LOH) was less frequent (19%). However, most samples with high M%NRAS had only one copy of NRAS locus surrounding regions suggesting a WT allele loss. Clinical characteristics and survival of patients with either <60% or ≥60% of M%NRAS were not different. CONCLUSION: As recently shown for M%BRAF, M%NRAS is highly heterogeneous. The clinical impacts of high M%NRAS should be investigated in a larger series of patients.


Assuntos
Cromossomos Humanos Par 1 , GTP Fosfo-Hidrolases/genética , Frequência do Gene , Melanoma/genética , Proteínas de Membrana/genética , Mutação , Neoplasias Cutâneas/genética , Adulto , Idoso , Idoso de 80 Anos ou mais , Aberrações Cromossômicas , Variações do Número de Cópias de DNA , Feminino , Humanos , Estimativa de Kaplan-Meier , Masculino , Melanoma/mortalidade , Pessoa de Meia-Idade , Estudos Retrospectivos , Neoplasias Cutâneas/mortalidade
15.
Blood ; 130(2): 176-180, 2017 07 13.
Artigo em Inglês | MEDLINE | ID: mdl-28566492

RESUMO

Langerhans cell histiocytosis (LCH) and the non-LCH neoplasm Erdheim-Chester disease (ECD) are heterogeneous neoplastic disorders marked by infiltration of pathologic macrophage-, dendritic cell-, or monocyte-derived cells in tissues driven by recurrent mutations activating MAPK signaling. Although recent data indicate that at least a proportion of LCH and ECD patients have detectable activating kinase mutations in circulating hematopoietic cells and bone marrow-based hematopoietic progenitors, functional evidence of the cell of origin of histiocytosis from actual patient materials has long been elusive. Here, we provide evidence for mutations in MAPK signaling intermediates in CD34+ cells from patients with ECD and LCH/ECD, including detection of shared origin of LCH and acute myelomonocytic leukemia driven by TET2-mutant CD34+ cell progenitors in one patient. We also demonstrate functional self-renewal capacity for CD34+ cells to drive the development of histiocytosis in xenotransplantation assays in vivo. These data indicate that the cell of origin of at least a proportion of patients with systemic histiocytoses resides in hematopoietic progenitor cells prior to committed monocyte/macrophage or dendritic cell differentiation and provide the first example of a patient-derived xenotransplantation model for a human histiocytic neoplasm.


Assuntos
Células da Medula Óssea/patologia , Proteínas de Ligação a DNA/genética , Doença de Erdheim-Chester/patologia , Células-Tronco Hematopoéticas/patologia , Histiocitose de Células de Langerhans/patologia , Proteínas Proto-Oncogênicas B-raf/genética , Proteínas Proto-Oncogênicas/genética , Adulto , Alelos , Animais , Antígenos CD34/genética , Antígenos CD34/imunologia , Células da Medula Óssea/imunologia , Transplante de Medula Óssea , Diferenciação Celular , Proteínas de Ligação a DNA/imunologia , Células Dendríticas/imunologia , Células Dendríticas/patologia , Doença de Erdheim-Chester/genética , Doença de Erdheim-Chester/imunologia , Expressão Gênica , Células-Tronco Hematopoéticas/imunologia , Histiocitose de Células de Langerhans/genética , Histiocitose de Células de Langerhans/imunologia , Humanos , Imunofenotipagem , Macrófagos/imunologia , Macrófagos/patologia , Camundongos , Monócitos/imunologia , Monócitos/patologia , Mutação , Proteínas Proto-Oncogênicas/imunologia , Proteínas Proto-Oncogênicas B-raf/imunologia , Transplante Heterólogo
16.
Br J Haematol ; 178(3): 457-467, 2017 08.
Artigo em Inglês | MEDLINE | ID: mdl-28444728

RESUMO

The BRAFV600E mutation is reported in half of patients with Langerhans cell histiocytosis (LCH). This study investigated the detection of the BRAFV600E allele in circulating cell-free (ccf) DNA in a paediatric LCH cohort. Children with BRAFV600E -mutated LCH were investigated to detect ccf BRAFV600E at diagnosis (n = 48) and during follow-up (n = 17) using a picolitre-droplet digital PCR assay. At diagnosis, ccf BRAFV600E was positive in 15/15 (100%) patients with risk-organ positive multisystem (RO+ MS) LCH, 5/12 (42%) of patients with RO- MS LCH and 3/21 (14%) patients with single-system (SS) LCH (P < 0·001, Fisher's exact test). The positive BRAFV600E load was higher for RO+ patients (mean, 2·90%; range, 0·04-11·4%) than for RO- patients (mean, 0·16%; range, 0·01-0·39) (P = 0·003, Mann-Whitney U test). After first-line vinblastine-steroid induction therapy, 7/7 (100%) of the non-responders remained positive for ccf BRAFV600E compared to 2/4 (50%) of the partial-responders and 0/4 of the complete responders (P = 0·002, Fisher's exact test). Six children treated with vemurafenib showed a clinical response that was associated with a decrease in the ccf BRAFV600E load at day 15. Thus, ccf BRAFV600E is a promising biomarker for monitoring the response to therapy for children with RO+ MS LCH or RO- LCH resistant to first-line chemotherapy.


Assuntos
Histiocitose de Células de Langerhans/diagnóstico , Proteínas Proto-Oncogênicas B-raf/sangue , Adolescente , Alelos , Biomarcadores/sangue , Sistema Livre de Células/metabolismo , Criança , Pré-Escolar , Monitoramento de Medicamentos/métodos , Quimioterapia Combinada , Feminino , Seguimentos , Glucocorticoides/uso terapêutico , Histiocitose de Células de Langerhans/tratamento farmacológico , Histiocitose de Células de Langerhans/genética , Humanos , Indóis/uso terapêutico , Lactente , Masculino , Mutação , Prognóstico , Proteínas Proto-Oncogênicas B-raf/genética , Sulfonamidas/uso terapêutico , Vemurafenib , Vimblastina/uso terapêutico
17.
J Pathol ; 242(1): 10-15, 2017 05.
Artigo em Inglês | MEDLINE | ID: mdl-28127763

RESUMO

Germline alterations in DNA repair genes are implicated in cancer predisposition and can result in characteristic mutational signatures. However, specific mutational signatures associated with base excision repair (BER) defects remain to be characterized. Here, by analysing a series of colorectal cancers (CRCs) using exome sequencing, we identified a particular spectrum of somatic mutations characterized by an enrichment of C > A transversions in NpCpA or NpCpT contexts in three tumours from a MUTYH-associated polyposis (MAP) patient and in two cases harbouring pathogenic germline MUTYH mutations. In two series of adrenocortical carcinomas (ACCs), we identified four tumours with a similar signature also presenting germline MUTYH mutations. Taken together, these findings demonstrate that MUTYH inactivation results in a particular mutational signature, which may serve as a useful marker of BER-related genomic instability in new cancer types. Copyright © 2017 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.


Assuntos
Neoplasias do Córtex Suprarrenal/genética , Carcinoma Adrenocortical/genética , Neoplasias Colorretais/genética , DNA Glicosilases/genética , Mutação , Animais , DNA Glicosilases/deficiência , Análise Mutacional de DNA/métodos , DNA de Neoplasias/genética , Predisposição Genética para Doença , Mutação em Linhagem Germinativa , Humanos , Camundongos Knockout , Transcriptoma/genética
18.
J Clin Oncol ; 34(25): 3023-30, 2016 09 01.
Artigo em Inglês | MEDLINE | ID: mdl-27382093

RESUMO

PURPOSE: Langerhans cell histiocytosis (LCH) is an inflammatory myeloid neoplasia with a broad spectrum of clinical manifestations and outcomes in children. The somatic BRAF(V600E) mutation occurs frequently, but clinical significance remains to be determined. PATIENTS AND METHODS: BRAF(V600E) mutation was investigated in a French LCH cohort. We analyzed associations between mutation status and clinical presentation, extent of disease, reactivation rate, response to therapy, and long-term permanent sequelae. RESULTS: Among 315 patients with successfully determined BRAF status, 173 (54.6%) carried a BRAF(V600E) mutation. Patients with BRAF(V600E) manifested more severe disease than did those with wild-type BRAF. Patients with BRAF(V600E) comprised 87.8% of patients (43 of 49) with multisystem LCH with risk organ involvement (liver, spleen, hematology), 68.6% of patients (35 of 51) with multisystem LCH without risk organ involvement, 43.9% of patients (86 of 196) with single-system LCH, and 42.1% of patients (8 of 19) with lung-involved LCH (P < .001). BRAF(V600E) mutation was also associated with organ involvement that could lead to permanent, irreversible damage, such as neurologic (75%) and pituitary (72.9%) injuries. Compared with patients with wild-type BRAF, patients with BRAF(V600E) more commonly displayed resistance to combined vinblastine and corticosteroid therapy (21.9% v 3.3%; P = .001), showed a higher reactivation rate (5-year reactivation rate, 42.8% v 28.1%; P = .006), and had more permanent, long-term consequences from disease or treatment (27.9% v 12.6%; P = .001). CONCLUSION: In children with LCH, BRAF(V600E) mutation was associated with high-risk features, permanent injury, and poor short-term response to chemotherapy. Further population-based studies should be undertaken to confirm our observations and to assess the impact of BRAF inhibitors for this subgroup of patients who may benefit from targeted therapy.


Assuntos
Protocolos de Quimioterapia Combinada Antineoplásica/uso terapêutico , Histiocitose de Células de Langerhans/tratamento farmacológico , Histiocitose de Células de Langerhans/genética , Mutação , Proteínas Proto-Oncogênicas B-raf/genética , Adolescente , Corticosteroides/administração & dosagem , Protocolos de Quimioterapia Combinada Antineoplásica/farmacologia , Criança , Pré-Escolar , Estudos de Coortes , Resistencia a Medicamentos Antineoplásicos , Feminino , França/epidemiologia , Histiocitose de Células de Langerhans/enzimologia , Histiocitose de Células de Langerhans/epidemiologia , Humanos , Lactente , Recém-Nascido , Masculino , Terapia de Alvo Molecular , Proteínas Proto-Oncogênicas B-raf/antagonistas & inibidores , Sistema de Registros , Vimblastina/administração & dosagem
19.
Exp Dermatol ; 25(6): 472-4, 2016 06.
Artigo em Inglês | MEDLINE | ID: mdl-26990546

RESUMO

One-fifth of cutaneous melanomas have dominant gain-of-function mutations of the NRAS oncogene. We report the first two cases of increasing NRAS mutant allele frequency in melanoma metastases and show that the chromosomal mechanism of this homozygosity is an increased polysomy of chromosome 1. We observed an increase in NRAS mutant allele percentage (NRAS-MA%) in the metastatic melanoma progression from 2 patients with melanomas harbouring a NRAS mutation (p.Q61K in case 1 and p.Q61R in case 2). In case 1, we observed a NRAS-MA% increase from 18% within the first metastatic node to 81%, 92% and 85% respectively in the three subsequent metastases: lymph node, brain and subcutaneous metastases biopsied 1, 6 and 17 months, respectively, after the initial lymph node biopsy. In case 2, we observed an increase in NRAS-MA% from 40% within the primary melanoma to 63% within the metastatic lymph node. FISH analysis showed the same results in both cases: a frequent polysomy of chromosome 1 in metastasis samples with NRAS mutant allele percentage >60%, while most cells were disomic in the samples with well-balanced heterozygous mutations. The percentage of NRAS mutant allele may increase during metastatic progression and may be associated with chromosomal instability. Further studies are needed to evaluate the prognostic impact of the NRAS homozygous status and/or polyploidy in metastatic cutaneous melanomas.


Assuntos
Duplicação Cromossômica , Cromossomos Humanos Par 1 , GTP Fosfo-Hidrolases/genética , Mutação com Ganho de Função , Melanoma/genética , Proteínas de Membrana/genética , Idoso , Humanos , Masculino , Pessoa de Meia-Idade
20.
BMC Cancer ; 15: 497, 2015 Jul 04.
Artigo em Inglês | MEDLINE | ID: mdl-26141748

RESUMO

BACKGROUND: BRAF mutations are present in 40% of human skin melanomas. Mutated tumors with an increased percentage of BRAF mutant alleles (BRAF-M%) may have a better response to RAF/MEK inhibitors. We evaluated the BRAF-M% in melanomas, and the genetic causes of its variation. METHODS: BRAF-M% was quantified by pyrosequencing, real-time PCR (rtPCR) and/or picoliter-droplet PCR (dPCR). BRAF mutant expression was detected by immunohistochemistry. Chromosomal alterations were analyzed with fluorescence in situ hybridization (FISH), and single nucleotide polymorphism (SNP) arrays. RESULTS: BRAF-M% quantification obtained with pyrosequencing was highly correlated (R = 0.94) with rtPCR, and with dPCR. BRAF-M% quantified from DNA and RNA were also highly correlated (R = 0.98). Among 368 samples with >80% tumor cells, 38.6% had a BRAF (V600E) mutation. Only 66.2% cases were heterozygous (BRAF-M% 30 to 60%). Increased BRAF-M% (>60%) was observed in 19% of cases. FISH showed a polysomy of chromosome 7 in 13.6%, 35.3% and 54.5% of BRAF wild-type, heterozygous and non-heterozygous BRAF-mutated samples, respectively (P < 0.005). Amplification (5.6%) and loss (3.2%) of BRAF locus were rare. By contrast, chromosome 7 was disomic in 27/27 BRAF-mutated nevi. CONCLUSIONS: BRAF-M% is heterogeneous and frequently increased in BRAF-mutant melanomas. Aneuploidy of chromosome 7 is more frequent in BRAF mutant melanomas, specifically in those with high BRAF-M%.


Assuntos
Melanoma/genética , Proteínas Proto-Oncogênicas B-raf/genética , Aneuploidia , Cromossomos Humanos Par 7/genética , Heterozigoto , Humanos , Hibridização in Situ Fluorescente , Melanoma/epidemiologia , Polimorfismo de Nucleotídeo Único/genética , Reação em Cadeia da Polimerase em Tempo Real
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