RESUMO
Glioblastoma (GBM) is a lethal malignancy whose clinical intransigence has been linked to extensive intraclonal genetic and phenotypic diversity and the common emergence of therapeutic resistance. This interpretation embodies the implicit assumption that cancer stem cells or tumor-propagating cells are themselves genetically and functionally diverse. To test this, we screened primary GBM tumors by SNP array to identify copy number alterations (a minimum of three) that could be visualized in single cells by multicolor fluorescence in situ hybridization. Interrogation of neurosphere-derived cells (from four patients) and cells derived from secondary transplants of these same cells in NOD-SCID mice allowed us to infer the clonal and phylogenetic architectures. Whole-exome sequencing and single-cell genetic analysis in one case revealed a more complex clonal structure. This proof-of-principle experiment revealed that subclones in each GBM had variable regenerative or stem cell activity, and highlighted genetic alterations associated with more competitive propagating activity in vivo.
Assuntos
Neoplasias Encefálicas/genética , Neoplasias Encefálicas/metabolismo , Variação Genética , Glioblastoma/genética , Glioblastoma/metabolismo , Fenótipo , Animais , Neoplasias Encefálicas/patologia , Linhagem Celular Tumoral , Variações do Número de Cópias de DNA , Progressão da Doença , Estudo de Associação Genômica Ampla , Genômica , Glioblastoma/patologia , Xenoenxertos , Sequenciamento de Nucleotídeos em Larga Escala , Humanos , Hibridização in Situ Fluorescente , Camundongos , Células-Tronco Neoplásicas/metabolismo , Células-Tronco Neoplásicas/patologia , Polimorfismo de Nucleotídeo Único , Análise de Célula ÚnicaRESUMO
BACKGROUND: Elevated levels of glutathione (GSH) have been reported to play an important role in mediating chemoresistance in tumor cells. The regulation of gamma-glutamylcysteine synthetase (gamma-GCS) is one of the major determinants of GSH homeostasis. The aim of our study was to investigate gamma-GCS gene expression in patients affected by acute myeloid leukemia (AML). METHODS: A total of 64 AML samples, including 23 acute promyelocytic leukemia (APL or M3) cases, were included in the study. gamma-GCS mRNA levels were determined by real-time quantitative RT-PCR. All patients were evaluated at diagnosis, whereas post-treatment gamma-GCS mRNA levels were assessed at the end of the consolidation therapy in 16 cases. RESULTS: Our data showed that variable degrees of gamma-GCS expression were detectable in AML, likely reflecting disease heterogeneity; in particular, APL cases, compared to the other AML subsets, showed both significantly lower basal levels of gamma-GCS mRNA at presentation and significantly increased mRNA levels after treatment. CONCLUSIONS: Decreased levels of gamma-GCS leading to reduced GSH may at least in part explain the higher sensitivity of APL to chemotherapy.
