RESUMO
Intrauterine growth restriction (IUGR) is associated with reduced activity of placental amino acid transport systems beta and A. Whether this phenotype is maintained in fetal cells outside the placenta is unknown. In IUGR, cord blood tumor necrosis factor (TNF)-alpha concentrations are raised, potentially influencing amino acid transport in fetal cells. We used fetal T lymphocytes as a model to study systems beta and A amino acid transporters in IUGR compared with normal pregnancy. We also studied the effect of TNF-alpha on amino acid transporter activity. In fetal lymphocytes from IUGR pregnancies, taurine transporter mRNA expression encoding system beta transporter was reduced, but there was no change in system beta activity. No significant differences were observed in system A mRNA expression (encoding SNAT1 and SNAT2) or system A activity between the two groups. After 24 or 48 h TNF-alpha treatment, fetal T lymphocytes from normal pregnancies showed no significant change in system A or system beta activity, although cell viability was compromised. This study represents the first characterization of amino acid transport in a fetal cell outside the placenta in IUGR. We conclude that the reduced amino acid transporter activity found in placenta in IUGR is not a feature of all fetal cells.
Assuntos
Sistema A de Transporte de Aminoácidos/metabolismo , Retardo do Crescimento Fetal/metabolismo , Glicoproteínas de Membrana/metabolismo , Proteínas de Membrana Transportadoras/metabolismo , Linfócitos T/metabolismo , Fator de Necrose Tumoral alfa/metabolismo , Sistema A de Transporte de Aminoácidos/genética , Peso ao Nascer , Sobrevivência Celular , Células Cultivadas , Feminino , Sangue Fetal/imunologia , Sangue Fetal/metabolismo , Retardo do Crescimento Fetal/imunologia , Idade Gestacional , Humanos , Recém-Nascido , Masculino , Glicoproteínas de Membrana/genética , Proteínas de Membrana Transportadoras/genética , Gravidez , RNA Mensageiro/metabolismo , Proteínas Recombinantes/metabolismo , Linfócitos T/imunologia , Fatores de TempoRESUMO
Fanconi anemia (FA) is an inherited disease with congenital abnormalities and an extreme risk of acute myeloid leukemia (AML). Genetic events occurring during malignant transformation in FA and the biology of FA-associated AML are poorly understood, but are often preceded by the development of chromosomal aberrations involving 3q26-29 in bone marrow of FA patients. We report here the molecular cytogenetic characterization of FA-derived AML cell lines SB1685CB and SB1690CB by conventional and array comparative genomic hybridization, fluorescence in situ hybridization, and SKY. We identified gains of a 3.7 MB chromosomal region on 3q26.2-26.31, which preceded transformation to overt leukemia. This region harbors the oncogenic transcription factor EVI1. A third FA-derived cell line, FA-AML1, carried a translocation with ectopic localization of 3q26 including EVI1. Rearrangements of 3q, which are rare in childhood AML, commonly result in overexpression of EVI1, which determines specific gene expression patterns and confers poor prognosis. We detected overexpression of EVI1 in all three FA-derived AML. Our results suggest a link between the FA defect, chromosomal aberrations involving 3q and overexpression of EVI1. We hypothesize that constitutional or acquired FA defects might be a common factor for the development of 3q abnormalities in AML. In addition, cryptic imbalances as detected here might account for overexpression of EVI1 in AML without overt 3q26 rearrangements.
Assuntos
Proteína BRCA2/genética , Cromossomos Humanos Par 3/genética , Proteínas de Ligação a DNA/genética , Anemia de Fanconi/genética , Amplificação de Genes , Leucemia Mieloide/genética , Proto-Oncogenes/genética , Fatores de Transcrição/genética , Translocação Genética , Doença Aguda , Linhagem Celular , Criança , Proteínas de Ligação a DNA/biossíntese , Humanos , Proteína do Locus do Complexo MDS1 e EVI1 , Fatores de Transcrição/biossínteseRESUMO
Fanconi anemia (FA) is a rare autosomal recessive disorder characterized by congenital and developmental abnormalities, hypersensitivity to DNA cross-linking agents such as mitomycin C (MMC), and strong predisposition to acute myeloid leukemia (AML). In this article, we describe clinical and molecular findings in a boy with a severe FA phenotype who developed AML by the age of 2. Although he lacked a strong family history of cancer, he was subsequently shown to carry biallelic mutations in the FANCD1/BRCA2 gene. These included an IVS7 splice-site mutation, which is strongly associated with early AML in homozygous or compound heterozygous carrier status in FA-D1 patients. Myeloid leukemia cells from this patient have been maintained in culture for more than 1 year and have been designated as the SB1690CB cell line. Growth of SB1690CB is dependent on granulocyte macrophage colony stimulating factor or interleukin-3. This cell line has retained its MMC sensitivity and has undergone further spontaneous changes in the spectrum of cytogenetic aberrations compared with the primary leukemia. This is the second AML cell line derived from an FA-D1 patient and the first proof that malignant clones arising in FA patients can retain inherited MMC sensitivity. As FA-derived malignancies are normally not very responsive to treatment, this implies there are important mechanisms of acquiring correction of the cellular FA phenotype that would explain the poor chemoresponsiveness observed in FA-associated malignancies and might also play a role in the initiation and progression of cancer in the general population.