In this study we have exploited the power of insertional mutagenesis

In this study we have exploited the power of insertional mutagenesis to elucidate tumor progression pathways in mice carrying two oncogenes (family genes. genes that can collaborate with Myc in tumorigenesis, which include the gene family of transcription factors (3). The genes also play important roles in human cancer with evidence of both gain and loss of function in the context of different lineages and tumor types (examined in (4)). Indeed, is frequently involved in human leukemias where it is subject to a variety of chromosomal translocations causing gene fusions as well as gene amplification, deletion and inactivating point mutations (4,5). Of notice for the Lep present study, and are among the most highly over-expressed genes in child years acute lymphocytic leukemias (6). We recognized all three murine genes as targets for insertional mutagenesis and over-expression in a transgenic model in which this oncogene is usually directed to the T-cell compartment under the control of a CD2 expression cassette (3,7,8), suggesting that this genes share a redundant oncogenic function in the context of deregulated Myc. To explore this aspect of Runx function, we have studied CD2-transgenic mice that are prone to lymphoma development and display impaired thymocyte maturation with an accumulation of immature CD8 cells. Crossing with CD2-mice leads to early tumor onset (9) and our recent studies of the underlying mechanism have indicated that ectopic Myc over-rides the Runx2-imposed proliferation block, while Runx2 expression confers a low apoptotic rate, apparently neutralising the propensity of Myc to induce apoptosis in tumor cells (10,11). Despite the quick onset of tumors in transgenic mice, it appears that further events are required to complete oncogenic transformation. Rearranging gene analyses show that this tumors arise as outgrowths from an in the beginning polyclonal population in the postnatal thymus (9,12). The identification and characterization of progression genes in tumors is usually therefore of considerable interest for the further elucidation of this collaboration mechanism. Retroviral insertional mutagenesis is a classical method of identifying genes relevant to malignancy, and has been particularly effective in the study of haematopoietic malignancies (13). Based on the assumption that retroviral insertion is usually effectively random, the occurrence of a common insertion site in impartial tumors is usually indicative of a selective process driving tumorigenesis and the proximity of a gene whose expression or function is usually affected by retroviral integration. The development of high throughput PCR methods and completion of human and murine genome sequences has led 86408-72-2 to a resurgence of interest in the use of retroviruses as genetic screening tools in malignancy. Analysis of mice infected with strains of MLV 86408-72-2 or retrotransposons has revealed many genes with the potential to be targeted1. More processed developments of this approach include collaboration tagging, where the technique is used to detect co-operating genes in mice transporting a dominant oncogene or with 86408-72-2 a defect in a tumor suppressor gene (3,14-17) and complementation tagging, where mutagenesis is used to tag functional homologues of genes in mice deleted in one or more known targets (18). More recently, contamination of mice with a defect in DNA repair has been employed to shift the target gene spectrum towards tumor suppressor loci (19). In this study we show that retroviral insertional mutagenesis can be used to elucidate the rate-limiting actions in tumor progression and identify the gene families and pathways that drive this process. Materials and 86408-72-2 Methods Transgenic mice and lymphomas CD2-transgenic mice (hereafter described as animals revealed exclusively multicentric lymphomas from which high molecular excess weight DNA was isolated. All animal work was carried out in line with the UK Animals (Scientific 86408-72-2 Procedures) Take action of 1986. Cloning of proviral insertion sites Proviral insertion sites were amplified using the splinkerette-based approach.

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