RESUMO
G-quadruplex DNAs form four-stranded helical structures and are proposed to play key roles in different cellular processes. Targeting G-quadruplex DNAs for cancer treatment is a very promising prospect. Here, we show that CX-5461 is a G-quadruplex stabilizer, with specific toxicity against BRCA deficiencies in cancer cells and polyclonal patient-derived xenograft models, including tumours resistant to PARP inhibition. Exposure to CX-5461, and its related drug CX-3543, blocks replication forks and induces ssDNA gaps or breaks. The BRCA and NHEJ pathways are required for the repair of CX-5461 and CX-3543-induced DNA damage and failure to do so leads to lethality. These data strengthen the concept of G4 targeting as a therapeutic approach, specifically for targeting HR and NHEJ deficient cancers and other tumours deficient for DNA damage repair. CX-5461 is now in advanced phase I clinical trial for patients with BRCA1/2 deficient tumours (Canadian trial, NCT02719977, opened May 2016).
Assuntos
Proteína BRCA1/deficiência , Proteína BRCA2/deficiência , Benzotiazóis/farmacologia , Benzotiazóis/uso terapêutico , Quadruplex G , Naftiridinas/farmacologia , Naftiridinas/uso terapêutico , Neoplasias/tratamento farmacológico , Animais , Sequência de Bases , Benzoxazinas/farmacologia , Caenorhabditis elegans/efeitos dos fármacos , Linhagem Celular Tumoral , Instabilidade Cromossômica/genética , Dano ao DNA , Reparo do DNA/efeitos dos fármacos , Replicação do DNA/efeitos dos fármacos , DNA Ribossômico/genética , Feminino , Quadruplex G/efeitos dos fármacos , Genoma Humano , Genótipo , Recombinação Homóloga/efeitos dos fármacos , Humanos , Camundongos , Quinolonas/farmacologia , Saccharomyces cerevisiae/metabolismo , Transcrição Gênica/efeitos dos fármacos , Ensaios Antitumorais Modelo de XenoenxertoRESUMO
BRCA2 mutations are significantly associated with early-onset breast cancer, and the tumour-suppressing function of BRCA2 has been attributed to its involvement in homologous recombination (HR)-mediated DNA repair. In order to identify additional functions of BRCA2, we generated BRCA2-knockout HCT116 human colorectal carcinoma cells. Using genome-wide microarray analyses, we have discovered a link between the loss of BRCA2 and the up-regulation of a subset of interferon (IFN)-related genes, including APOBEC3F and APOBEC3G. The over-expression of IFN-related genes was confirmed in different human BRCA2(-/-) and mouse Brca2(-/-) tumour cell lines, and was independent of senescence and apoptosis. In isogenic wild-type BRCA2 cells, we observed over-expression of IFN-related genes after treatment with DNA-damaging agents, and following ionizing radiation. Cells with endogenous DNA damage because of defective BRCA1 or RAD51 also exhibited over-expression of IFN-related genes. Transcriptional activity of the IFN-stimulated response element (ISRE) was increased in BRCA2 knockout cells, and the expression of BRCA2 greatly decreased IFNα-stimulated ISRE reporter activity, suggesting that BRCA2 directly represses the expression of IFN-related genes through the ISRE. Finally, the colony-forming capacity of BRCA2 knockout cells was significantly reduced in the presence of either IFNß or IFNγ, suggesting that IFNs may have potential as therapeutic agents in cancer cells with BRCA2 mutations. The GEO Accession No. for microarray analysis is GSE54830.
Assuntos
Proteína BRCA2/genética , Regulação Neoplásica da Expressão Gênica/genética , Interferons/genética , Neoplasias/genética , Animais , Proteína BRCA2/deficiência , Linhagem Celular Tumoral , Imunoprecipitação da Cromatina , Técnicas de Inativação de Genes , Genes BRCA2 , Humanos , Camundongos , Análise de Sequência com Séries de Oligonucleotídeos , Reação em Cadeia da Polimerase em Tempo Real , Elementos de Resposta/genética , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Regulação para CimaRESUMO
We conducted a genome-wide association (GWA) study of lung cancer comparing 511,919 SNP genotypes in 1,952 cases and 1,438 controls. The most significant association was attained at 15q25.1 (rs8042374; P = 7.75 x 10(-12)), confirming recent observations. Pooling data with two other GWA studies (5,095 cases, 5,200 controls) and with replication in an additional 2,484 cases and 3,036 controls, we identified two newly associated risk loci mapping to 6p21.33 (rs3117582, BAT3-MSH5; P(combined) = 4.97 x 10(-10)) and 5p15.33 (rs401681, CLPTM1L; P(combined) = 7.90 x 10(-9)).
Assuntos
Carcinoma Pulmonar de Células não Pequenas/genética , Cromossomos Humanos Par 5/genética , Cromossomos Humanos Par 6/genética , Predisposição Genética para Doença , Neoplasias Pulmonares/genética , Estudos de Casos e Controles , Estudo de Associação Genômica Ampla , Humanos , Polimorfismo de Nucleotídeo ÚnicoRESUMO
To identify risk variants for lung cancer, we conducted a multistage genome-wide association study. In the discovery phase, we analyzed 315,450 tagging SNPs in 1,154 current and former (ever) smoking cases of European ancestry and 1,137 frequency-matched, ever-smoking controls from Houston, Texas. For replication, we evaluated the ten SNPs most significantly associated with lung cancer in an additional 711 cases and 632 controls from Texas and 2,013 cases and 3,062 controls from the UK. Two SNPs, rs1051730 and rs8034191, mapping to a region of strong linkage disequilibrium within 15q25.1 containing PSMA4 and the nicotinic acetylcholine receptor subunit genes CHRNA3 and CHRNA5, were significantly associated with risk in both replication sets. Combined analysis yielded odds ratios of 1.32 (P < 1 x 10(-17)) for both SNPs. Haplotype analysis was consistent with there being a single risk variant in this region. We conclude that variation in a region of 15q25.1 containing nicotinic acetylcholine receptors genes contributes to lung cancer risk.
Assuntos
Cromossomos Humanos Par 15/genética , Predisposição Genética para Doença , Neoplasias Pulmonares/genética , Proteínas do Tecido Nervoso/genética , Polimorfismo de Nucleotídeo Único , Receptores Nicotínicos/genética , Idoso , Cisteína Endopeptidases/genética , Feminino , Ligação Genética , Testes Genéticos , Genoma Humano , Haplótipos , Humanos , Masculino , Pessoa de Meia-IdadeRESUMO
For Genetic Analysis Workshop 15 Problem 2, we organized data from several ongoing studies designed to identify genetic and environmental risk factors for rheumatoid arthritis. Data were derived from the North American Rheumatoid Arthritis Consortium (NARAC), collaboration among Canadian researchers, the European Consortium on Rheumatoid Arthritis Families (ECRAF), and investigators from Manchester, England. All groups used a common standard for defining rheumatoid arthritis, but NARAC also further selected for a more severe phenotype in the probands. Genotyping and family structures for microsatellite-based linkage analysis were provided from all centers. In addition, all centers but ECRAF have genotyped families for linkage analysis using SNPs and these data were additionally provided. NARAC also had additional data from a dense genotyping analysis of a region of chromosome 18 and results from candidate gene studies, which were provided. Finally, smoking influences risk for rheumatoid arthritis, and data were provided from the NARAC study on this behavior as well as some additional phenotypes measuring severity. Several questions could be evaluated using the data that were provided. These include comparing linkage analysis using single-nucleotide polymorphisms versus microsatellites and identifying credible regions of linkage outside the HLA region on chromosome 6p13, which has been extensively documented; evaluating the joint effects of smoking with genetic factors; and identifying more homogenous subsets of families for whom genetic susceptibility might be stronger, so that linkage and association studies may be more efficiently conducted.