Project description:Breast cancer is the most prevalent cancer in women, and most cases are believed to have a sporadic, rather than heritable basis. Therefore, a major challenge in cancer research is to determine the underlying genomic alterations leading to carcinogenesis and malignancy, and then use this information for personalized therapies. Genomic studies of human cancers that aim to identify causative mutations are complicated by the prevalence of passenger mutations, genetic heterogeneity, and the diversity of breast cancer etiologies and tumor subtypes. Mouse cancer models are powerful for untangling the genomic basis of cancers because genetic and phenotypic variation can be eliminated or controlled. To identify genes contributing to mammary tumorigenesis, we exploited the C3H-Mcm4Chaos3/Chaos3 (“Chaos3”) mouse model that, by virtue of bearing a defective DNA replicative helicase subunit that causes elevated genomic instability (GIN), sustains somatic alterations ultimately causing mammary adenocarcinomas. Genomic analysis of Chaos3 mammary tumors revealed recurrent copy number alterations (CNAs) of specific genomic regions, most notably deletion of the Neurofibromin 1 (Nf1) tumor suppressor gene in all cases. NF1, a negative regulator of RAS, is traditionally recognized for its role in driving the development of neurofibromas in the context of the human disease Neurofibromitosis but not breast cancer. We observed elevated RAS activation and increased sensitivity of both Chaos3 and human Nf1-mutated breast cancer lines to MAPK and/or PI3K/AKT pathway inhibitors. We also found striking overlap between Chaos3 CNAs and human breast cancer CNA data curated in public genomic databases, including Nf1 deletion. Together, our results indicate that spontaneous NF1 loss can drive breast cancer and suggests a potential therapeutic strategy in that subset of patients. reference x sample
Project description:Breast cancer is the most prevalent cancer in women 1, and most cases are believed to have a sporadic, rather than heritable basis 2. To identify breast cancer driver genes, we exploited the C3H-Mcm4Chaos3/Chaos3 (“Chaos3”) mouse model that, by virtue of bearing a defective DNA replicative helicase subunit that causes elevated genomic instability (GIN), sustains somatic alterations ultimately causing mammary adenocarcinomas 6. Array Comparative Genomic Hybridization (aCGH) analysis of Chaos3 mammary tumors revealed recurrent copy number alterations (CNAs), most notably deletion of the Neurofibromin 1 (Nf1) tumor suppressor gene in all cases. NF1, a negative regulator of RAS, is traditionally recognized for its role in driving the development of neurofibromas in the context of the human disease Neurofibromatosis Type 1, but not breast cancer. Genomic DNA from tumor and reference samples were hybridized to NimbleGen 3x720K mouse CGH arrays. Two reference samples were used independently. CNAs were visualized using Nimblegen, IGV, and KCsmart software 32. Select genes were validated via qPCR. Critical regions within each Chaos3 CNA were identified as the region with the greatest overlap across multiple Chaos3 tumors. Recurring Copy Number Variations (CNVs) for 12 Chaos3 tumors and 2 MMTV-Neu mammary tumors analyzed by aCGH are indicated. Samples analyzed are primary tumors except where indicated.
Project description:Breast cancer is the most prevalent cancer in women, and most cases are believed to have a sporadic, rather than heritable basis. Therefore, a major challenge in cancer research is to determine the underlying genomic alterations leading to carcinogenesis and malignancy, and then use this information for personalized therapies. Genomic studies of human cancers that aim to identify causative mutations are complicated by the prevalence of passenger mutations, genetic heterogeneity, and the diversity of breast cancer etiologies and tumor subtypes. Mouse cancer models are powerful for untangling the genomic basis of cancers because genetic and phenotypic variation can be eliminated or controlled. To identify genes contributing to mammary tumorigenesis, we exploited the C3H-Mcm4Chaos3/Chaos3 (“Chaos3”) mouse model that, by virtue of bearing a defective DNA replicative helicase subunit that causes elevated genomic instability (GIN), sustains somatic alterations ultimately causing mammary adenocarcinomas. Genomic analysis of Chaos3 mammary tumors revealed recurrent copy number alterations (CNAs) of specific genomic regions, most notably deletion of the Neurofibromin 1 (Nf1) tumor suppressor gene in all cases. NF1, a negative regulator of RAS, is traditionally recognized for its role in driving the development of neurofibromas in the context of the human disease Neurofibromitosis but not breast cancer. We observed elevated RAS activation and increased sensitivity of both Chaos3 and human Nf1-mutated breast cancer lines to MAPK and/or PI3K/AKT pathway inhibitors. We also found striking overlap between Chaos3 CNAs and human breast cancer CNA data curated in public genomic databases, including Nf1 deletion. Together, our results indicate that spontaneous NF1 loss can drive breast cancer and suggests a potential therapeutic strategy in that subset of patients.
Project description:Breast cancer is the most prevalent cancer in women 1, and most cases are believed to have a sporadic, rather than heritable basis 2. To identify breast cancer driver genes, we exploited the C3H-Mcm4Chaos3/Chaos3 (“Chaos3”) mouse model that, by virtue of bearing a defective DNA replicative helicase subunit that causes elevated genomic instability (GIN), sustains somatic alterations ultimately causing mammary adenocarcinomas 6. Array Comparative Genomic Hybridization (aCGH) analysis of Chaos3 mammary tumors revealed recurrent copy number alterations (CNAs), most notably deletion of the Neurofibromin 1 (Nf1) tumor suppressor gene in all cases. NF1, a negative regulator of RAS, is traditionally recognized for its role in driving the development of neurofibromas in the context of the human disease Neurofibromatosis Type 1, but not breast cancer. Genomic DNA from tumor and reference samples were hybridized to NimbleGen 3x720K mouse CGH arrays. Two reference samples were used independently. CNAs were visualized using Nimblegen, IGV, and KCsmart software 32. Select genes were validated via qPCR. Critical regions within each Chaos3 CNA were identified as the region with the greatest overlap across multiple Chaos3 tumors.
Project description:We investigated the CNAs in a four stage tumorigenesis model. This model included copy number analyses in non-transgenic NMRI mice (normal) and in transgenic SVT/t mice: non-malignant hyperplastic mammary glands and breast cancers, as well as breast cancer derived cell lines. We focused our research on copy number analyses to compare the genomic alterations that occur during tumorigenesis. We addressed the question, whether common predisposed chromosomal breakpoints could be seen to promote malignant transformation. We can report a characteristic increase of copy number alterations from normal to tumor stage in our model. Furthermore, we have identified chromosomal segments and found characteristic fragmentations.
Project description:We investigated the CNAs in a four stage tumorigenesis model. This model included copy number analyses in non-transgenic NMRI mice (normal) and in transgenic SVT/t mice: non-malignant hyperplastic mammary glands and breast cancers, as well as breast cancer derived cell lines. We focused our research on copy number analyses to compare the genomic alterations that occur during tumorigenesis. We addressed the question, whether common predisposed chromosomal breakpoints could be seen to promote malignant transformation. We can report a characteristic increase of copy number alterations from normal to tumor stage in our model. Furthermore, we have identified chromosomal segments and found characteristic fragmentations. Affymetrix SNP array analysis was performed with Mouse Diversity Genotyping Arrays (Affymetrix). DNA was extracted from frozen biopsies of mammary tumor samples of six mice and two cell lines. Normalization and allele summarization were performed with the BRLMM-P algorithm provided and copy number analysis was performed for the each sample using the average signal intensity of both normal samples as the reference for copy number inference.
Project description:To investigate the impact of combined Rb and p53 loss in mammary tumorigenesis, we used transgenic and viral approaches to delete Rb and p53 floxed alleles specifically in the mouse mammary epithelium. Although MMTV-Cre (NLST) targets stem/bi-potent progenitors in the mammary gland, a subset of MMTV-Cre:Rbf/f;p53f/f mice developed non-mammary tumors. Thus, freshly isolated primary mammary epithelial cells from these animals were transplanted into the mammary fat pads of immunodeficient mice and monitored for tumor formation. In addition, primary MECs were isolated from Cre-negative Rbf/f;p53f/f mice, infected with Ad-Cre followed by orthotopic transplantation. In all these cases, resulting tumors shared similar spindle-shape histology, expressed high levels of vimentin, a mesenchymal marker, but not E-cadherin, a luminal marker, and were classified as adeno-sacrcomatoid/spindle-cell/mesenchymal-like breast cancer. We used aCGH to detect copy number alterations associated with Rb/p53 deletion. Tumor DNAs from MMTV-Cre: Rbf/f;p53f/f and Ad-Cre: Rbf/f;p53f/f conditional mutant mice are being compared to pooled tail DNAs in order to identify common alterations associated with Rb/p53 deficient tumorigenesis
Project description:Recurrent karyotypic abnormalities are a characteristic feature of cervical cancer (CC) cells, which may result in deregulated expression of important genes that contribute to tumor initiation and progression. To examine the role of genomic copy number alterations, we surveyed genetic lesions in CC utilizing single nucleotide polymorphism (SNP) array. We identified specific genetic alterations associated with CC. These data will be useful in identification of target altered genes, novel markers for predicting high risk precancerous lesions to invasive cancer, comparison of copy number alterations with gene expression changes can provide gene targets for pharmacologic intervention. We demonstrate specific regions of gene amplification (e.g., 11q22), copy number gains (e.g., 3q, 5p, and 20q), and deletions (e.g., 2q, 11q23) in the present study, which forma a framework for identification of critical genes in CC tumorigenesis. Keywords: Cervical cancer, copy number alterations, HPV type, gene amplification
Project description:Genomic rearrangements may cause both Mendelian and complex disorders. Currently, several major mechanisms causing genomic rearrangements have been proposed such as non-allelic homologous recombination (NAHR), non-homologous end joining (NHEJ), fork stalling and template switching (FoSTeS) and microhomology-mediated break-induced replication (MMBIR). However, to what extent these mechanisms contribute to gene-specific pathogenic copy-number changes (CNCs) remains understudied. Furthermore, only few studies resolved these pathogenic alterations at nucleotide-level resolution. Accordingly, our aim is to explore which mechanisms contribute to a large, unique set of locus-specific non-recurrent genomic rearrangements causing the genetic neurocutaneous disorder neurofibromatosis type 1 (NF1). Through breakpoint-spanning PCR as well as array Comparative Genomic Hybridization (aCGH), we have identified the breakpoints and characterized the likely rearrangement mechanism of the NF1 intragenic CNCs in 78 unrelated patients. Unlike the most typical recurrent rearrangements mediated by flanking low copy repeats (LCRs), NF1 intragenic CNCs have diverse breakpoint locations, and are characterized by different rearrangement mechanisms. We propose the DNA replication-based mechanisms comprising FoSTeS/MMBIR and serial replication stalling to be the predominant mechanism leading to NF1 intragenic CNCs. In addition to the loop of a 197-bp palindrome located in intron 40, four Alu elements located in intron 1, 2, 3 and 50 were also identified as significant intragenic rearrangement hotspots within the NF1 gene. However, no clear genotype-phenotype correlations could be identified among the NF1 patients carrying NF1 intragenic CNCs.