RESUMO
BACKGROUND: A genetic predisposition to acute lymphoblastic leukemia (ALL) in childhood is well established. Currently known risk loci, however, explain only one third of the estimated total risk related to common genetic variations. PROCEDURE: We genotyped 1,421 polymorphisms in 407 candidate genes from the SNP500Cancer database (National Cancer Institute) using the Illumina Cancer SNP Panel. We investigated 78 cases (aged 0-19 years at diagnosis, and mixed ethnic background) of childhood B-precursor ALL and compared genotype data with those of 1,417 HapMap controls. To account for the ethnic diversity of the study population, structured association by genetically matching cases and controls using identity-by-state similarity was used. Case-control association analyses were performed using Cochran-Mantel-Haenszel tests, adjusted for the population substructure. RESULTS: Common variations rs6966 (3' UTR of PPP1R13L, chr 19q13.32, P = 4.55 × 10(-9)) and rs414580 (intron 2 of MSR1, chr 8p22, P = 6.09 × 10(-8)) were significantly associated with ALL. These SNPs remained significant after adjustment for multiple testing. The SNP rs6966 tags a haplotype block which includes SNPs in PPP1R13L and ERCC2 genes, which are related to DNA repair and cell survival. rs6966 and rs414580 conferred allelic odds ratios of 3.74 (95% confidence interval [CI] 2.31-6.04) and 3.93 (95% CI 2.31-6.69), respectively. CONCLUSIONS: These findings reveal two independent novel susceptibility loci for childhood ALL.
Assuntos
Loci Gênicos , Predisposição Genética para Doença , Testes Genéticos , Polimorfismo de Nucleotídeo Único , Leucemia-Linfoma Linfoblástico de Células Precursoras/genética , Regiões 3' não Traduzidas , Adolescente , Criança , Pré-Escolar , Feminino , Humanos , Íntrons , Masculino , Estudos RetrospectivosRESUMO
BACKGROUND: Cisplatin is one of the most effective chemotherapeutic agents in the treatment of several solid tumors including osteosarcoma (OS). Despite aggressive treatment, 25% of patients with OS continue to die from their disease. Since cisplatin based regimens have been uniformly used in OS therapy, treatment failure is likely due, at least in part, to cisplatin resistance. PROCEDURE: The objective of this study was to determine the relationship between MKP-1 expression and cisplatin sensitivity of OS cell lines and to explore the mechanism underlying this relationship. Three OS cell lines were examined for their MKP-1 expression and cisplatin sensitivity. JNK phosphorylation and apoptosis induction was also measured. Western and Northern blot, flow cytometry, siRNA, and MTT assays were used. RESULTS: U2OS cells, which express high level of MKP-1, are less sensitive to cisplatin-induced cell death. Inhibition of MKP-1 by siRNA silencing sensitizes U2OS cells to cisplatin-induced cell death. Furthermore, delayed apoptosis induction following cisplatin treatment was observed in U2OS, in parallel to decreased JNK activation, increased MKP-1 expression and relatively increased cisplatin resistance. Interestingly, triptolide, an MKP-1 inhibitor, blocks MKP-1 expression and enhances cisplatin-induced cell death. CONCLUSION: High MKP-1 expression is associated with decreased sensitivity or increased resistance to cisplatin-induced cell death in OS cell lines, and MKP-1 could potentially be used as a marker of cisplatin resistance and a therapeutic target for molecular therapies.
Assuntos
Antineoplásicos/uso terapêutico , Cisplatino/uso terapêutico , Resistencia a Medicamentos Antineoplásicos , Fosfatase 1 de Especificidade Dupla/metabolismo , Osteossarcoma/tratamento farmacológico , Osteossarcoma/enzimologia , Apoptose/efeitos dos fármacos , Northern Blotting , Western Blotting , Neoplasias Ósseas/tratamento farmacológico , Neoplasias Ósseas/enzimologia , Neoplasias Ósseas/patologia , Proliferação de Células/efeitos dos fármacos , Fosfatase 1 de Especificidade Dupla/antagonistas & inibidores , Fosfatase 1 de Especificidade Dupla/genética , Fosfatases de Especificidade Dupla , Citometria de Fluxo , Humanos , Proteínas Quinases JNK Ativadas por Mitógeno/metabolismo , Fosfatases da Proteína Quinase Ativada por Mitógeno , Osteossarcoma/patologia , Fosforilação/efeitos dos fármacos , RNA Interferente Pequeno/farmacologia , Transdução de Sinais/efeitos dos fármacos , Células Tumorais CultivadasRESUMO
BACKGROUND: Traditional multiplexed gene expression methods require well preserved, intact RNA. Such specimens are difficult to acquire in clinical practice where formalin fixation is the standard procedure for processing tissue. Even when special handling methods are used to obtain frozen tissue, there may be RNA degradation; for example autopsy samples where degradation occurs both pre-mortem and during the interval between death and cryopreservation. Although specimens with partially degraded RNA can be analyzed by qRT-PCR, these analyses can only be done individually or at low levels of multiplexing and are laborious and expensive to run for large numbers of RNA targets. METHODS: We evaluated the ability of the cDNA-mediated Annealing, Selection, extension, and Ligation (DASL) assay to provide highly multiplexed analyses of cryopreserved and formalin fixed, paraffin embedded (FFPE) tissues obtained at autopsy. Each assay provides data on 1536 targets, and can be performed on specimens with RNA fragments as small as 60 bp. RESULTS: The DASL performed accurately and consistently with cryopreserved RNA obtained at autopsy as well as with RNA extracted from formalin-fixed paraffin embedded tissue that had a cryopreserved mirror image specimen with high quality RNA. In FFPE tissue where the cryopreserved mirror image specimen was of low quality the assay performed reproducibly on some but not all specimens. CONCLUSION: The DASL assay provides reproducible results from cryopreserved specimens and many FFPE specimens obtained at autopsy. Gene expression analyses of these specimens may be especially valuable for the study of non-cancer endpoints, where surgical specimens are rarely available.
