Retrotransposition in Colorectal Cancer
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ABSTRACT: The purpose of this study is to ascertain the locations of somatic LINE-1 retrotransposition events in human colon tumor samples by pooling multiple tumor samples from different patients and performing a targeted resequencing assay (Ewing and Kazazian, Genome Research 2010) to sequence the 3' flanking regions of all insertions in the pooled sample. The result is compared to the result of applying the same method to pooled normal samples from the same patients as were used in the pooled tumor sample and selecting sites that show an insertion in the tumor but not in the normaltissue and do not correspond to any known non-reference LINE-1 insertion allele. The selected sites are then validated by site-specific PCR and capillary sequencing to confirm that they represent LINE-1 insertions and to obtain breakpoint sequences.
SECONDARY ACCESSION(S): PRJNA173389PRJNA173390
REPOSITORIES: dbGaP
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Project description:<p>The purpose of this study is to ascertain the locations of somatic LINE-1 retrotransposition events in human colon tumor samples by pooling multiple tumor samples from different patients and performing a targeted resequencing assay (Ewing and Kazazian, Genome Research 2010) to sequence the 3′flanking regions of all insertions in the pooled sample. The result is compared to the result of applying the same method to pooled normal samples from the same patients as were used in the pooled tumor sample and selecting sites that show an insertion in the tumor but not in the normaltissue and do not correspond to any known non-reference LINE-1 insertion allele. The selected sites are then validated by site-specific PCR and capillary sequencing to confirm that they represent LINE-1 insertions and to obtain breakpoint sequences.</p>
| phs000536.v1.p1 | EGA
Project description:Somatic transposon mutagenesis in mice is an efficient strategy to investigate the genetic mechanisms of tumorigenesis. The identification of tumor driving transposon insertions traditionally requires the generation of large tumor cohorts to obtain information about common insertion sites. Tumor driving insertions are also characterized by their clonal expansion in tumor tissue, a phenomenon that is facilitated by the slow and evolving transformation process of transposon mutagenesis. We describe here an improved approach for the detection of tumor driving insertions that assesses the clonal expansion of insertions by quantifying the relative proportion of sequence reads obtained in individual tumors. To this end, we have developed a protocol for insertion site sequencing that utilizes acoustic shearing of tumor DNA and Illumina sequencing. We analyzed various solid tumors generated by PiggyBac mutagenesis and for each tumor >10^6 reads corresponding to >10^4 insertion sites were obtained. In each tumor, 9 to 25 insertions stood out by their enriched sequence read frequencies when compared to frequencies obtained from tail DNA controls. These enriched insertions are potential clonally expanded tumor driving insertions, and thus identify candidate cancer genes. The candidate cancer genes of our study comprised many established cancer genes, but also novel candidate genes such as Mastermind-like1 (Mamld1) and Diacylglycerolkinase delta (Dgkd). We show that clonal expansion analysis by high-throughput sequencing is a robust approach for the identification of candidate cancer genes in insertional mutagenesis screens on the level of individual tumors. Solid tumors in mice were generated by somatic transposon mutagenesis with a PiggyBac transposon system. Insertion sites of transposons in 11 tumors and 6 non-cancerous tail controls were determined by Illumina high-throughput sequencing. Insertions were determined both on 5' and 3' sides of the transposon (PB5 and PB3, respectively). Quantitative analysis of read numbers revealed enrichment of certain insertions in tumors, but not in controls, and these enriched insertions identify candidate cancer genes.
2013-08-28 | E-GEOD-46210 | biostudies-arrayexpress
Project description:Insertions occur when a segment of one chromosome is translocated and inserted into a new region of the same chromosome or a non-homologous chromosome. We report 69 cases with unbalanced insertions identified using array CGH and FISH, representing 1.25% of 5,683 cases referred to our laboratory for array CGH and found to have copy-number abnormalities. Although the majority of insertions were non-recurrent, several recurrent unbalanced insertions were detected, including three der(Y)ins(Y;18)(q?11.2;p11.32p11.32)pat inherited from parents carrying an unbalanced insertion. The clinical significance of these recurrent rearrangements is unclear, although the small size, limited gene content, and inheritance pattern of each suggests the phenotypic consequences may be benign. Moreover, cryptic, submicroscopic duplications were observed at or near the insertion sites in two patients, further confounding the clinical interpretation of these insertions. Using FISH, linear amplification and array CGH we identified a 126-kb duplicated region from 19p13.3 inserted into MECP2 at Xq28 in a patient with symptoms of Rett syndrome. Our results demonstrate that although the interpretation of most non-recurrent insertions is unclear without high-resolution insertion site characterization, the potential for an otherwise benign duplication to result in a clinically relevant outcome through the disruption of a gene necessitates the use of FISH to determine whether copy-number gains detected by array CGH represent tandem duplications or unbalanced insertions. Further follow-up testing using techniques such as linear amplification coupled with array CGH or sequencing should be used to determine gene involvement at the insertion site after FISH has identified the presence of an insertion. 88 total samples analyzed. No replicates included. Each sample run against a standard sex-matched control.
2011-02-28 | E-GEOD-27080 | biostudies-arrayexpress
Project description:Somatic transposon mutagenesis in mice is an efficient strategy to investigate the genetic mechanisms of tumorigenesis. The identification of tumor driving transposon insertions traditionally requires the generation of large tumor cohorts to obtain information about common insertion sites. Tumor driving insertions are also characterized by their clonal expansion in tumor tissue, a phenomenon that is facilitated by the slow and evolving transformation process of transposon mutagenesis. We describe here an improved approach for the detection of tumor driving insertions that assesses the clonal expansion of insertions by quantifying the relative proportion of sequence reads obtained in individual tumors. To this end, we have developed a protocol for insertion site sequencing that utilizes acoustic shearing of tumor DNA and Illumina sequencing. We analyzed various solid tumors generated by PiggyBac mutagenesis and for each tumor >10^6 reads corresponding to >10^4 insertion sites were obtained. In each tumor, 9 to 25 insertions stood out by their enriched sequence read frequencies when compared to frequencies obtained from tail DNA controls. These enriched insertions are potential clonally expanded tumor driving insertions, and thus identify candidate cancer genes. The candidate cancer genes of our study comprised many established cancer genes, but also novel candidate genes such as Mastermind-like1 (Mamld1) and Diacylglycerolkinase delta (Dgkd). We show that clonal expansion analysis by high-throughput sequencing is a robust approach for the identification of candidate cancer genes in insertional mutagenesis screens on the level of individual tumors.
2013-08-28 | GSE46210 | GEO
Project description:Insertions occur when a segment of one chromosome is translocated and inserted into a new region of the same chromosome or a non-homologous chromosome. We report 69 cases with unbalanced insertions identified using array CGH and FISH, representing 1.25% of 5,683 cases referred to our laboratory for array CGH and found to have copy-number abnormalities. Although the majority of insertions were non-recurrent, several recurrent unbalanced insertions were detected, including three der(Y)ins(Y;18)(q?11.2;p11.32p11.32)pat inherited from parents carrying an unbalanced insertion. The clinical significance of these recurrent rearrangements is unclear, although the small size, limited gene content, and inheritance pattern of each suggests the phenotypic consequences may be benign. Moreover, cryptic, submicroscopic duplications were observed at or near the insertion sites in two patients, further confounding the clinical interpretation of these insertions. Using FISH, linear amplification and array CGH we identified a 126-kb duplicated region from 19p13.3 inserted into MECP2 at Xq28 in a patient with symptoms of Rett syndrome. Our results demonstrate that although the interpretation of most non-recurrent insertions is unclear without high-resolution insertion site characterization, the potential for an otherwise benign duplication to result in a clinically relevant outcome through the disruption of a gene necessitates the use of FISH to determine whether copy-number gains detected by array CGH represent tandem duplications or unbalanced insertions. Further follow-up testing using techniques such as linear amplification coupled with array CGH or sequencing should be used to determine gene involvement at the insertion site after FISH has identified the presence of an insertion.
2011-02-28 | GSE27080 | GEO
Project description:The National Cancer Institute-60 (NCI-60) cell lines are among the most widely used models of human cancer. They provide a platform to integrate DNA sequence information, epigenetic data, RNA and protein expression, and pharmacologic susceptibilities in studies of cancer cell biology. Genome-wide studies of the NCI-60 have included exome sequencing, karyotyping, and copy number analyses but have not targeted repetitive sequences. Interspersed repeats are a significant source of heritable genetic variation, and insertions of active elements can occur somatically in malignancy. To approach a functional understanding of these sequences in transformed cells, we used transposon insertion profiling (TIP) to map Long INterspersed Element-1 (LINE-1, L1) and Alu Short INterspersed Element (SINE) insertions in cancer genes in NCI-60 cells. As expected, this identified known insertions, polymorphisms shared in unrelated tumor cell lines, as well as unique, potentially tumor-specific insertions. Here, we report a map of these insertion sites and conduct association analyses relating individual insertions to a variety of cellular phenotypes.
2017-02-09 | GSE83756 | GEO
Project description:The noncoding regions of tumor cell genomes harbor a considerable fraction of total variation, but the functional contribution of such variants to tumorigenesis is ill-defined. Among these noncoding variants, somatic insertions are among the least well-characterized due to challenges with interpreting short-read DNA sequences. To address this, we have identified enhancer-associated small insertion variants across a spectrum of tumor cells by using ChIP-seq to enrich and sequence enhancer DNA, and a computational approach with multiple alignment procedures to identify small insertions. Among the 82 tumor genomes studied here, small insertions were frequently observed in enhancer DNA sequences located near known oncogenes. Further study of one such insertion, found in primary leukemia tumor genomes, revealed that it nucleates formation of an active enhancer that drives expression of the LMO2 oncogene. The catalogue of enhancer-associated small insertion variants described here provides a foundation for further investigating the functions of this class of variants across a range of human cancers.
2016-07-08 | GSE76783 | GEO
Project description:Ewing tumor cell line SBSR-AKS grows adherent to the culture vessel. A spontaneously derived sub-line of cell line SBSR-AKS shows growth in suspension. We used microarrays to analyse gene expression in these Ewing tumor cell lines Established Ewing tumor cell lines were grown under standard conditions
2011-09-29 | E-GEOD-24806 | biostudies-arrayexpress
Project description:The oncogenic fusion protein PML/RAR is expressed in most cases of acute promyelocytic leukemia (APL). In transgenic models, PML/RAR is able to induce a preleukemic state. However, it is not sufficient to induce leukemia, which develops with low frequency (~50%) and long latency (about 1 year). These data indicate that secondary genetic cooperating alterations are required in order to induce leukemia. In an effort to identify the genes that cooperate in the leukemogenesis PML/RAR-dependent, we performed an insertional mutagenesis screening infecting the PML/RAR KI mice with Moloney Murine Leukemia Virus (MLV). The infection of the PML/RAR KI mice significantly accelerated the onset (~6 months) and increased the penetrance (~75% of infected animals) of the leukemia. To identify genes mutated by the proviral integrations, flanking sequences of the retrovirus insertions were cloned by IPCR and analysed by parallel sequencing. We sequenced DNAs from the spleen of 48 independent leukemic mice. After filtering, ~133,000 reads were univocally mapped onto the mouse genome. Of them, ~131,000 were present more than once in the DNA from the same mouse and produced a total of 1,707 independent genomic insertions (retroviral insertion sites - RISs). To identify chromosomal regions that are frequently mutated by retrovirus insertions (common insertion sites; CISs), we evaluated the density of RISs distribution over the mouse genome, using statistical approaches that calculate the significance of RISs occurrence (p<0.05) within specific genomic regions (Monte Carlo simulation or Kernel Convolution). The two different approaches identified the same set of 221 CISs. Finally, we identified 271 genes putatively targeted by retroviral insertions in the 221 CISs. These putative targets appeared to be enriched in genes identified as relevant cancer-genes in different tumor types. Moreover, from a biological point of view, our screening was performed in saturating conditions. Therefore, to our knowledge, our is the first report of an exhaustive list of virtually all the mouse genes that functionally cooperate with PML/RAR in the induction of APL.
2016-12-31 | GSE72528 | GEO
Project description:The ability to chronicle transcription factor binding events throughout the development of an organism would facilitate mapping of transcriptional networks that control cell fate decisions. We describe a method for permanently recording protein-DNA interactions in mammalian cells. We endow transcription factors with the ability to deposit a transposon into the genome near to where they bind. The transposon becomes a M-bM-^@M-^\Calling CardM-bM-^@M-^] the transcription factor leaves behind to record its visit to the genome. The locations of the Calling Cards can be determined by massively-parallel DNA sequencing. We show that the transcription factor SP1 fused to the piggyBac transposase directs insertion of the piggyBac transposon near SP1 binding sites. The locations of transposon insertions are highly reproducible, and agree with sites of SP1-binding determined by ChIP-seq. Genes bound by SP1 are more likely to be expressed in the HCT116 cell line we used, and SP1-bound CpG islands show a strong preference to be unmethylated. This method has the potential to trace transcription factor binding throughout cellular and organismal development in a way that has heretofore not been possible. These data contain mapped insertion sites from the piggyBac (PB) transposon into HCT116 cell line and sequenced using an Illumina GAII analyzer. The first set contains the insertion sites of transposons mapped from the wild-type PB transposase and the second set contains the insertion sites of transposons mapped with the PB transposase fused to the transcription factor SP1. Other sequencing data present are ChIP-seq data for SP1 in the HCT116 cell line and RNA-seq data.
2011-12-31 | E-GEOD-34791 | biostudies-arrayexpress