RESUMO
We examined copy number changes in the genomes of B cells from 58 patients with chronic lymphocytic leukemia (CLL) by using representational oligonucleotide microarray analysis (ROMA), a form of comparative genomic hybridization (CGH), at a resolution exceeding previously published studies. We observed at least 1 genomic lesion in each CLL sample and considerable variation in the number of abnormalities from case to case. Virtually all abnormalities previously reported also were observed here, most of which were indeed highly recurrent. We observed the boundaries of known events with greater clarity and identified previously undescribed lesions, some of which were recurrent. We profiled the genomes of CLL cells separated by the surface marker CD38 and found evidence of distinct subclones of CLL within the same patient. We discuss the potential applications of high-resolution CGH analysis in a clinical setting.
Assuntos
Aberrações Cromossômicas , Perfilação da Expressão Gênica , Leucemia Linfocítica Crônica de Células B/genética , Análise de Sequência com Séries de Oligonucleotídeos/métodos , ADP-Ribosil Ciclase 1 , Mapeamento Cromossômico , Cromossomos Artificiais Bacterianos , Cromossomos Humanos/genética , Hibridização Genômica Comparativa , DNA de Neoplasias/genética , Dosagem de Genes , Regulação Leucêmica da Expressão Gênica , Genoma Humano , Instabilidade Genômica , Humanos , Hibridização in Situ Fluorescente , Cariotipagem , Leucemia Linfocítica Crônica de Células B/diagnóstico , Neutrófilos/citologia , Neutrófilos/metabolismo , Prognóstico , Células Tumorais CultivadasRESUMO
DBC2 is a tumor suppressor gene linked to breast and lung cancers. Although DBC2 belongs to the RHO GTPase family, it has a unique structure that contains a Broad-Complex/Tramtrack/Bric a Brac (BTB) domain at the C terminus instead of a typical CAAX motif. A limited number of functional studies on DBC2 have indicated its participation in diverse cellular activities, such as ubiquitination, cell-cycle control, cytoskeleton organization and protein transport. In this study, the role of DBC2 in protein transport was analyzed using vesicular stomatitis virus glycoprotein (VSVG) fused with green fluorescent protein. We discovered that DBC2 knockdown hinders the VSVG transport system in 293 cells. Previous studies have demonstrated that VSVG is transported via the microtubule motor complex. We demonstrate that DBC2 mobility depends also on an intact microtubule network. We conclude that DBC2 plays an essential role in microtubule-mediated VSVG transport from the endoplasmic reticulum to the Golgi apparatus.
Assuntos
Proteínas de Ligação ao GTP/fisiologia , Glicoproteínas de Membrana/fisiologia , Proteínas Supressoras de Tumor/fisiologia , Proteínas do Envelope Viral/fisiologia , Motivos de Aminoácidos , Linhagem Celular , Retículo Endoplasmático/metabolismo , Proteínas de Ligação ao GTP/genética , Complexo de Golgi/metabolismo , Guanosina Trifosfato/metabolismo , Humanos , Microtúbulos/metabolismo , Transporte Proteico , Proteínas Recombinantes de Fusão/fisiologia , Proteínas Supressoras de Tumor/genéticaRESUMO
A previously uncharacterized gene, DBC2 (deleted in breast cancer), was cloned from a homozygously deleted region at human chromosome 8p21. DBC2 contains a highly conserved RAS domain and two putative protein interacting domains. Our analyses indicate that DBC2 is the best candidate tumor suppressor gene from this region. It lies within the epicenter of the deletions and is homozygously deleted in 3.5% (7/200) of breast tumors. Mutation analysis of DBC2 led to discovery of two instances of somatic missense mutations in breast tumor specimens, whereas no missense mutations were found in other candidates from the region. Unlike other genes in the region, expression of DBC2 is often extinguished in breast cancer cells or tissues. Moreover, our functional analysis revealed that DBC2 expression in breast cancer cells lacking DBC2 transcripts causes growth inhibition. By contrast, expression of a somatic mutant discovered in a breast cancer specimen does not suppress the growth of breast cancer cells.
