RESUMO
Molecular cancer diagnostics are an important clinical advance in cancer management, but new methods are still needed. In this context, gene expression signatures obtained by microarray represent a useful molecular diagnostic. Here, we describe novel probe-level microarray analyses that reveal connections between mRNA processing and neoplasia in multiple tumor types, with diagnostic potential. We now show that characteristic differences in mRNA processing, primarily in the 3'-untranslated region, define molecular signatures that can distinguish similar tumor subtypes with different survival characteristics, with at least 74% accuracy. Using a mouse model of B-cell leukemia/lymphoma, we find that differences in transcript isoform abundance are likely due to both alternative polyadenylation (APA) and differential degradation. While truncation of the 3'-UTR is the most common observed pattern, genes with elongated transcripts were also observed, and distinct groups of affected genes are found in related but distinct tumor types. Genes with elongated transcripts are overrepresented in ontology categories related to cell-cell adhesion and morphology. Analysis of microarray data from human primary tumor samples revealed similar phenomena. Western blot analysis of selected proteins confirms that changes in the 3'-UTR can correlate with changes in protein expression. Our work suggests that alternative mRNA processing, particularly APA, can be a powerful molecular biomarker with prognostic potential. Finally, these findings provide insights into the molecular mechanisms of gene deregulation in tumorigenesis.
Assuntos
Linfoma de Células B/genética , Linfoma de Células B/patologia , RNA Mensageiro/genética , Regiões 3' não Traduzidas , Animais , Feminino , Regulação Neoplásica da Expressão Gênica , Humanos , Linfoma de Células B/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , MicroRNAs/genética , Análise de Sequência com Séries de Oligonucleotídeos , Neoplasias Ovarianas/genética , Neoplasias Ovarianas/metabolismo , Isoformas de Proteínas , Proteína Supressora de Tumor p53/deficiênciaRESUMO
Chromosomal instability is a hallmark of many tumor types. Complex chromosomal rearrangements with associated gene amplification, known as complicons, characterize many hematologic and solid cancers. Whereas chromosomal aberrations, including complicons, are useful diagnostic and prognostic cancer markers, their molecular origins are not known. Although accumulating evidence has implicated DNA double-strand break repair in suppression of oncogenic genome instability, the genomic elements required for chromosome rearrangements, especially complex lesions, have not been elucidated. Using a mouse model of B-lineage lymphoma, characterized by complicon formation involving the immunoglobulin heavy chain (Igh) locus and the c-myc oncogene, we have now investigated the requirement for specific genomic segments as donors for complex rearrangements. We now show that specific DNA double-strand breaks, occurring within a narrow segment of Igh, are necessary to initiate complicon formation. By contrast, neither specific DNA breaks nor the powerful intronic enhancer Emu are required for complicon-independent oncogenesis. This study is the first to delineate mechanisms of complex versus simple instability and the first to identify specific chromosomal elements required for complex chromosomal aberrations. These findings will illuminate genomic cancer susceptibility and risk factors.
Assuntos
Aberrações Cromossômicas , Dano ao DNA , Reparo do DNA , Amplificação de Genes , Rearranjo Gênico , Genes myc , Cadeias Pesadas de Imunoglobulinas/genética , Linfócitos/fisiologia , Linfoma de Células B/genética , Translocação Genética , Animais , Modelos Animais de Doenças , Predisposição Genética para Doença , Região de Junção de Imunoglobulinas/genética , Linfoma de Células B/epidemiologia , Linfoma de Células B/imunologia , Camundongos , Fatores de RiscoRESUMO
Treatment of nonmalignant childhood disorders by bone marrow transplantation (BMT) is limited by toxicity from preparatory regimens and immune consequences associated with engraftment of allogeneic donor cells. Using costimulatory blockade (anti-CD40L mAb and CTLA-4Ig) combined with high-dose BMT in nonablated neonates, we obtained engraftment and established tolerance using both partially MHC mismatched (H2g7 into H2b) and fully mismatched BM (H2s into H2b). Recipients were mucopolysaccharidosis type VII (MPS VII) mice with lysosomal storage disease in order to assess therapeutic outcome. Recipients treated with donor lymphocyte infusion (DLI) amplified microchimerism to full donor. Recipients without DLI maintained long-term engraftment, tolerance, and had extended life spans. DLI increased donor cell mediated replacement of beta-glucuronidase (GUSB) activity in all tissues and maintained clearance of lysosomes better than in non-DLI-treated mice. DLI amplification of partially mismatched BM and fully mismatched BM caused late onset chronic GvHD in 56% and 100% of recipients, respectively.