RESUMO
Pleomorphic xanthoastrocytoma (PXA) is a rare, usually well-circumscribed and superficially located neoplasm that preferentially arises in the cerebral cortex of children and young adults. The molecular aberrations that are associated with these tumors have not been studied systematically so far. We here report on a molecular genetic analysis of 62 PXAs (46 PXAs of World Health Organization [WHO] grade II and 16 PXAs with anaplastic features) for alterations of 5 candidate genes known to be frequently aberrant in diffusely infiltrating astrocytic gliomas, i.e. TP53, CDKN2A (p16(INK4a)), CDK4, MDM2, and EGFR. Only 3 PXAs (5%) carried a TP53 mutation. None of the 62 PXAs had lost both copies of the CDKN2A gene. The CDK4, MDM2, or EGFR genes were not amplified in any of the tumors. Fourteen PXAs were additionally analyzed for loss of heterozygosity (LOH) at microsatellite markers located on the chromosomes/chromosomal arms 1, gp, 9p, 10, 17, 19q, and 22q. Two PXAs (14%) had LOH at all informative markers on 9p, while 1 PXA demonstrated an interstitial area of allelic imbalance between D22S533 and D22S417 at 22q11.2-q13.3. Further analysis of 10 PXAs for inactivation of the CDKN2A. p14(ARF), and CDKN2B (p15(INK4b)) genes on 9p21 did not reveal any homozygous deletion, mutation, promoter hypermethylation, or complete loss of mRNA expression. Taken together, our results indicate that the chromosomal and genetic aberrations in PXAs are different from those typically associated with the diffusely infiltrating astrocytic and oligodendroglial gliomas. These genetic differences likely contribute to the more favorable behavior of PXAs and may be helpful for the molecular differential diagnosis of cerebral gliomas.
Assuntos
Astrocitoma/genética , Astrocitoma/patologia , Neoplasias Encefálicas/genética , Neoplasias Encefálicas/patologia , Proteínas de Neoplasias/genética , Proteínas Nucleares , Adolescente , Adulto , Astrocitoma/classificação , Neoplasias Encefálicas/classificação , Criança , Pré-Escolar , Quinase 4 Dependente de Ciclina , Inibidor p16 de Quinase Dependente de Ciclina/genética , Quinases Ciclina-Dependentes/genética , Análise Mutacional de DNA , DNA de Neoplasias/análise , Receptores ErbB/genética , Feminino , Genes p53 , Humanos , Perda de Heterozigosidade , Masculino , Repetições de Microssatélites , Pessoa de Meia-Idade , Mutação , Proteínas de Neoplasias/metabolismo , Polimorfismo Conformacional de Fita Simples , Proteínas Proto-Oncogênicas/genética , Proteínas Proto-Oncogênicas c-mdm2 , Proteína Supressora de Tumor p53/genéticaRESUMO
Loss of heterozygosity (LOH) on the chromosome arms 1p and 19q is frequent in oligodendroglial tumors and has been correlated with chemosensitivity and good prognosis in anaplastic oligodendrogliomas. The oligodendroglioma-associated tumor suppressor genes on 1p and 19q are as yet unknown. To narrow down candidate regions on 1p, we investigated oligodendroglial tumors from 89 patients for LOH at up to 30 polymorphic loci on 1p. In addition, all tumors were studied for LOH at 7 loci on 19q. Combined LOH on 1p and 19q was detected in 20 (83%) of 24 oligodendrogliomas, 15(63%) of 24 anaplastic oligodendrogliomas, 10 (56%) of 18 oligoastrocytomas, and 12 (52%) of 23 anaplastic oligoastrocytomas. Five tumors demonstrated partial deletions on 1p, which allowed to define 3 distinct candidate regions at 1p36.31-pter distal to D1S2633, 1p36.22-p36.31 between D1S489 and D1S2642, and 1p34.2-p36.1 between D1S2743 and D1S482, respectively. No partial deletions were detected on 19q. Combined LOH on 1p and 19q was associated with prolonged time to progression (TTP), longer overall survival (OS), and a higher 5-year survival rate. Depending on the presence or absence of combined LOH on 1p and 19q, patients with anaplastic oligodendroglial tumors treated with adjuvant radio- and/or chemotherapy showed a median TTP of 86 months versus 39 months, a median OS of 91 months versus 46 months, and a 5-year survival rate of 80% versus 36%, respectively. Similarly, LOH on 1p and 19q was associated with longer survival in patients with low-grade oligodendroglial tumors (TTP: 57 months versus 47 months; OS: 172 months versus 105 months; 5-year survival rate: 92% versus 70%). Thus, our results refine the location of putative oligodendroglioma suppressor genes on 1p and support the significance of LOH on 1p and 19q as a favorable prognostic marker.
Assuntos
Astrocitoma/genética , Neoplasias Encefálicas/genética , Neoplasias Encefálicas/mortalidade , Cromossomos Humanos Par 1/genética , Oligodendroglioma/genética , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Astrocitoma/mortalidade , Astrocitoma/patologia , Neoplasias Encefálicas/patologia , Criança , Progressão da Doença , Feminino , Humanos , Perda de Heterozigosidade/genética , Masculino , Repetições de Microssatélites/genética , Pessoa de Meia-Idade , Oligodendroglioma/mortalidade , Oligodendroglioma/patologia , Reação em Cadeia da Polimerase , Prognóstico , Análise de Sobrevida , Taxa de SobrevidaRESUMO
PURPOSE: Evaluation of toxicity and efficacy of an alternating weekly regimen of temozolomide administered 1 week on and 1 week off in patients with recurrent glioma. PATIENTS AND METHODS: Ninety adult patients with recurrent gliomas accrued in one center received chemotherapy with temozolomide at 150 mg/m(2)/d (days 1 through 7 and 15 through 21 every 4 weeks) with individual dose adjustments according to hematologic toxicity. RESULTS: A total of 906 treatment weeks were delivered. Grade 4 hematotoxicity according to the Common Terminology Criteria for Adverse Events (CTCAE; version 3.0) was observed in 24 treatment weeks (2.6%). CTCAE grade 4 lymphopenia eventually developed in 11 patients (12%). There were neither cumulative lymphopenias nor opportunistic infections. The progression-free survival (PFS) rate at 6 months for glioblastoma patients was 43.8%. The median PFS in these patients was 24 weeks (95% CI, 17 to 26 weeks), the median survival time from diagnosis of progression was 38 weeks (95% CI, 30 to 46 weeks), and the 1-year survival rate from progression was 23%. O(6)-methylguanine DNA methyltransferase (MGMT) gene promoter methylation in the tumor tissue was not associated with longer PFS (log-rank P = .37). CONCLUSION: These data imply that the alternating weekly schedule is feasible, safe, and effective and clearly warrants investigation in randomized studies. Compared with more protracted low-dose temozolomide schedules, the 1-week-on/1-week-off schedule may be less toxic. We provide preliminary evidence that this dose-dense schedule is also active in patients with tumors lacking MGMT gene promoter methylation.
Assuntos
Antineoplásicos Alquilantes/administração & dosagem , Neoplasias Encefálicas/tratamento farmacológico , Dacarbazina/análogos & derivados , Glioma/tratamento farmacológico , Adulto , Antineoplásicos Alquilantes/efeitos adversos , Metilação de DNA , Dacarbazina/administração & dosagem , Dacarbazina/efeitos adversos , Progressão da Doença , Esquema de Medicação , Feminino , Humanos , Imageamento por Ressonância Magnética , Masculino , Pessoa de Meia-Idade , Recidiva Local de Neoplasia , Reação em Cadeia da Polimerase , Estudos Prospectivos , Análise de Sobrevida , Temozolomida , Resultado do TratamentoRESUMO
To identify novel genes involved in glioma progression we performed suppression subtractive hybridization combined with cDNA array analysis on 4 patients with primary low-grade gliomas of World Health Organization (WHO) grade II that recurred as secondary glioblastomas (WHO grade IV). Eight genes showing differential expression between primary and recurrent tumors in 3 of the 4 patients were selected for further analysis using real-time reverse transcription-PCR on a series of 10 pairs of primary low-grade and recurrent high-grade gliomas as well as 42 astrocytic gliomas of different WHO grades. These analyses revealed that 5 genes, i.e., AMOG (ATP1B2, 17p13.1), APOD (3q26.2-qter), DMXL1 (5q23.1) DRR1 (TU3A, 3p14.2) and PSD3 (KIAA09428/HCA67/EFA6R, 8p22), were expressed at significantly lower levels in secondary glioblastomas as compared to diffuse astrocytomas of WHO grade II. In addition, AMOG, DRR1 and PSD3 transcript levels were significantly lower in primary glioblastomas than in diffuse astrocytomas. Treatment of glioma cell lines with 5-aza-2'-deoxycytidine and trichostatin A resulted in increased expression of AMOG and APOD transcripts. Sequencing of sodium bisulfite-modified DNA demonstrated AMOG promoter hypermethylation in the glioma cell lines and 1 primary anaplastic astrocytoma with low AMOG expression. Taken together, we identified interesting novel candidate genes that likely contribute to glioma progression and provide first evidence for a role of epigenetic silencing of AMOG in malignant glioma cells.
Assuntos
Adenosina Trifosfatases/genética , Astrocitoma/genética , Neoplasias Encefálicas/genética , Proteínas de Transporte de Cátions/genética , Moléculas de Adesão Celular Neuronais/genética , Inativação Gênica , Hibridização de Ácido Nucleico , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Antimetabólitos Antineoplásicos/farmacologia , Apolipoproteínas/genética , Apolipoproteínas D , Azacitidina/análogos & derivados , Azacitidina/farmacologia , Biomarcadores Tumorais/genética , Metilação de DNA , Decitabina , Progressão da Doença , Perfilação da Expressão Gênica , Regulação Neoplásica da Expressão Gênica , Inativação Gênica/efeitos dos fármacos , Genes Supressores de Tumor , Glicoproteínas/genética , Fatores de Troca do Nucleotídeo Guanina , Histona Desacetilases/genética , Humanos , Ácidos Hidroxâmicos/farmacologia , Proteínas de Membrana Transportadoras/genética , Proteínas do Tecido Nervoso/genética , Proteínas Nucleares/genética , Hibridização de Ácido Nucleico/métodos , Análise de Sequência com Séries de Oligonucleotídeos , Inibidores da Síntese de Proteínas/farmacologia , Proteínas/genética , Reação em Cadeia da Polimerase Via Transcriptase Reversa/métodosRESUMO
PURPOSE: To evaluate toxicity and efficacy of the combination of lomustine, temozolomide (TMZ) and involved-field radiotherapy in patients with newly diagnosed glioblastoma (GBM). PATIENTS AND METHODS: Thirty-one adult patients (median Karnofsky performance score 90; median age, 51 years) accrued in two centers received involved-field radiotherapy (60 Gy in 2-Gy fractions) and chemotherapy with lomustine 100 mg/m2 (day 1) and TMZ 100 mg/m2/d (days 2 to 6) with individual dose adjustments according to hematologic toxicity. RESULTS: A median of five courses (range, one to six courses) were delivered. WHO grade 4 hematotoxicity was observed in five patients (16%) and one of these patients died as a result of septicemia. Nonhematologic toxicity included one patient with WHO grade 4 drug-induced hepatitis (leading to discontinuation of lomustine and TMZ) and one patient with WHO grade 2 lung fibrosis (leading to discontinuation of lomustine). The progression-free survival (PFS) rate at 6 months was 61.3%. The median PFS was 9 months (95% CI, 5.3 to 11.7 months), the median overall survival time (MST) was 22.6 months (95% CI, 12.5 to not assessable), the 2-year survival rate was 44.7%. O6-methylguanine-DNA methyltransferase (MGMT) gene-promoter methylation in the tumor tissue was associated with longer PFS (P = .014, log-rank test) and MST (P = .037). CONCLUSION: The combination of lomustine, TMZ, and radiotherapy had acceptable toxicity and yielded promising survival data in patients with newly diagnosed GBM. MGMT gene-promoter methylation was a strong predictor of survival.
Assuntos
Protocolos de Quimioterapia Combinada Antineoplásica/uso terapêutico , Metilação de DNA , Glioblastoma/tratamento farmacológico , Glioblastoma/radioterapia , O(6)-Metilguanina-DNA Metiltransferase/genética , Administração Oral , Adulto , Idoso , Protocolos de Quimioterapia Combinada Antineoplásica/efeitos adversos , Neoplasias Encefálicas/tratamento farmacológico , Neoplasias Encefálicas/radioterapia , Quimioterapia Adjuvante , Dacarbazina/administração & dosagem , Dacarbazina/efeitos adversos , Dacarbazina/análogos & derivados , Intervalo Livre de Doença , Esquema de Medicação , Feminino , Glioblastoma/genética , Humanos , Lomustina/administração & dosagem , Lomustina/efeitos adversos , Masculino , Pessoa de Meia-Idade , Valor Preditivo dos Testes , Prognóstico , Regiões Promotoras Genéticas , Radioterapia Adjuvante , Análise de Sobrevida , Temozolomida , Resultado do TratamentoRESUMO
The carboxyl-terminal modulator protein (CTMP) has been identified as a negative regulator of protein kinase B/Akt. Aberrant Akt signaling is frequently observed in glioblastomas, the most common and most malignant glial brain tumors. Because loss of CTMP function and/or expression may remove the inhibitory effects on Akt and promote tumorigenesis, we studied 93 primary glioblastomas and nine glioblastoma cell lines for CTMP deletion, mutation, promoter hypermethylation, and mRNA expression. None of the tumors or cell lines had CTMP-homozygous deletions or coding sequence mutations. However, CTMP mRNA expression was lower by at least 50% relative to non-neoplastic brain tissue in 37 (40%) glioblastomas and six (67%) glioma cell lines. Reduced CTMP mRNA levels were closely associated with hypermethylation of the CTMP promoter. Furthermore, treatment of CTMP-hypermethylated A172 glioma cells with the demethylating agent 5-aza-2'-deoxycytidine and the histone deacetylase inhibitor trichostatin A resulted in partial demethylation of the CTMP promoter and increased CTMP mRNA expression. Thus, epigenetic downregulation of CTMP transcription is a common aberration in glioblastomas.
Assuntos
Proteínas Adaptadoras de Transdução de Sinal , Azacitidina/análogos & derivados , Proteínas de Transporte/genética , Proteínas de Transporte/metabolismo , Glioblastoma/metabolismo , Proteínas de Membrana/genética , Proteínas de Membrana/metabolismo , Proteínas Serina-Treonina Quinases , Proteínas Proto-Oncogênicas/metabolismo , Transcrição Gênica , Antibióticos Antineoplásicos/farmacologia , Antimetabólitos Antineoplásicos/farmacologia , Azacitidina/farmacologia , Proteínas de Transporte/efeitos dos fármacos , Linhagem Celular Tumoral , Metilação de DNA/efeitos dos fármacos , Decitabina , Regulação para Baixo/efeitos dos fármacos , Deleção de Genes , Regulação Neoplásica da Expressão Gênica/efeitos dos fármacos , Humanos , Ácidos Hidroxâmicos/farmacologia , Proteínas de Membrana/efeitos dos fármacos , Mutação , Proteínas Proto-Oncogênicas c-akt , RNA Mensageiro/metabolismo , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Tioléster HidrolasesRESUMO
Ras signaling is important for the intracellular transduction of mitogenic stimuli from activated growth factor receptors. We have investigated 37 sporadic malignant melanomas (15 primary cutaneous melanomas and 22 melanoma metastases) and 6 melanoma cell lines for mutations in the 3 Ras genes NRAS, KRAS and HRAS. All tumors and cell lines were additionally analyzed for mutation and expression of BRAF, which encodes a Ras-regulated serine/threonine kinase with oncogenic properties, as well as for expression of RASSF1A, which encodes a Ras-binding protein with tumor suppressor properties. Mutational analyses identified somatic NRAS mutations in 2 primary melanomas, 4 melanoma metastases and 2 cell lines. One melanoma metastasis showed a somatic KRAS mutation whereas HRAS mutations were not detected. Eight primary melanomas, 6 melanoma metastases and 4 melanoma cell lines carried BRAF mutations affecting the known hot-spot codon 599. None of the tumors or cell lines with BRAF mutation demonstrated NRAS or KRAS mutations. Real-time reverse transcription-PCR showed that 8 melanomas (3 primary tumors, 5 melanoma metastases) had reduced RASSF1A transcript levels of < or =50% relative to benign melanocytic nevi and normal skin. Three melanoma cell lines lacked detectable RASSF1A transcripts. The RASSF1A gene promoter was hypermethylated in these 3 cell lines as well as in 6 of 8 melanomas with reduced RASSF1A mRNA levels. Treatment of the cell lines with 5-aza-2'-deoxycytidine and trichostatin A resulted in demethylation of the RASSF1A promoter and re-expression of RASSF1A transcripts. Most tumors and all cell lines with RASSF1A promoter methylation additionally carried BRAF or NRAS mutations, suggesting a synergistic effect of these aberrations on melanoma growth. Taken together, 57% of the investigated melanomas and 100% of the melanoma cell lines carried mutations in either NRAS, KRAS or BRAF. In addition, 22% of the melanomas and 50% of the cell lines showed reduced RASSF1A transcript levels. Thus, alterations of Ras pathway genes are of paramount importance in the pathogenesis of sporadic melanomas.
Assuntos
Azacitidina/análogos & derivados , Genes ras/fisiologia , Melanoma/genética , Mutação/genética , Proteínas Proto-Oncogênicas c-raf/genética , Transdução de Sinais , Proteínas Supressoras de Tumor/genética , Adulto , Idoso , Idoso de 80 Anos ou mais , Azacitidina/farmacologia , Metilação de DNA/efeitos dos fármacos , Metilases de Modificação do DNA/antagonistas & inibidores , Decitabina , Inibidores Enzimáticos , Feminino , Regulação Neoplásica da Expressão Gênica , Inibidores de Histona Desacetilases , Humanos , Ácidos Hidroxâmicos/farmacologia , Masculino , Melanoma/secundário , Pessoa de Meia-Idade , Regiões Promotoras Genéticas/genética , Proteínas Proto-Oncogênicas B-raf , Neoplasias Cutâneas/genética , Células Tumorais CultivadasRESUMO
Aberrant activation of the Wnt signaling pathway has been reported in different human tumor types, including malignant melanomas. We investigated 37 malignant melanomas (15 primary tumors and 22 metastases) for alterations of 4 genes encoding members of this pathway, i.e., CTNNB1 (beta-catenin gene, 3p22.1), APC (adenomatous polyposis coli gene, 5q22.2), BTRC (beta-transducin repeat-containing protein gene, 10q24.3) and ICAT (inhibitor of beta-catenin and Tcf-4, 1p36.2). Mutational analysis of CTNNB1 identified somatic mutations in 1 primary melanoma and 1 melanoma metastasis from 2 different patients (5%). Both mutations affected the N-terminal degradation box of beta-catenin, which is important for the regulation of beta-catenin homeostasis. Another primary melanoma carried a somatic APC missense mutation within the known mutation cluster region in exon 15. Fourteen tumors (40%) showed LOH at microsatellite markers on 1p36. None of the tumors had lost both copies of the ICAT gene, but 1 melanoma metastasis carried a somatic point mutation altering the translation start codon of ICAT. Real-time RT-PCR showed markedly reduced ICAT transcript levels (Assuntos
Proteína da Polipose Adenomatosa do Colo/genética
, Proteínas de Ciclo Celular
, Proteínas do Citoesqueleto/genética
, Proteínas de Ligação ao GTP/genética
, Melanoma/genética
, Proteínas Musculares/genética
, Mutação/genética
, Proteínas Repressoras
, Transdução de Sinais
, Transativadores
, Proteínas Adaptadoras de Transdução de Sinal
, Adulto
, Idoso
, Idoso de 80 Anos ou mais
, Análise Mutacional de DNA
, Feminino
, Regulação Neoplásica da Expressão Gênica
, Humanos
, Imuno-Histoquímica
, Peptídeos e Proteínas de Sinalização Intracelular
, Masculino
, Melanoma/metabolismo
, Pessoa de Meia-Idade
, Polimorfismo Conformacional de Fita Simples
, RNA Mensageiro/genética
, RNA Mensageiro/metabolismo
, beta Catenina
, Proteínas Contendo Repetições de beta-Transducina