Molecular and cytogenetic analysis of human diploid fibroblast cells transformed by simian virus 40: What causes immortalization?
Item
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Title
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Molecular and cytogenetic analysis of human diploid fibroblast cells transformed by simian virus 40: What causes immortalization?
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Identifier
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AAI9405572
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identifier
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9405572
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Creator
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Patsalis, Philippos C.
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Contributor
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Adviser: Ann S. Henderson
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Date
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1993
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Language
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English
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Publisher
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City University of New York.
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Subject
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Biology, Molecular | Biology, Genetics | Biology, General
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Abstract
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Transformation of human diploid fibroblasts (HF) with SV40 can result in extension of life span beyond the normal limit of senescence and in a minority of cases, immortalization. This study used comparison of matched parental (diploid) and immortalized cell lines to determine if any single genetic factor could be related to the immortalization phenomena. The integration site of SV40 was shown to be at chromosome 5q21 by cytologic hybridization. A comparison of mortal and immortal cells showed no alterations involving the integrated SV40 genome per se. Karyotypic analysis of matched cell lines, identified a specific chromosomal breakpoint (6q21) in immortalized cells that was not present in the parental line. Hybridization analysis confirmed that sequences on the distal portion of 6q are lost in immortalized cells. Two single copy DNAs which flanks the breakpoint were identified and used to further define the exact breakpoint on 6q13. FISH analysis demonstrated the region 6q13 {dollar}\to{dollar} 21 as belonging to another chromosome and confirmed the 6q13 breakpoint. A survey of random translocations and other anomalies occurring in the immortalized lines was also made. Some of these are regions known to contain oncogenes and transforming proteins. The MCC tumor suppressor gene was rearranged and deregulated. The genes DCC, Bcl-2, APC were also found to be deregulated. We propose that deletion of specific sequences due to breakage of chromosome 6q represent one of the mutational events responsible for immortalization of SV40 transformed HF. In addition, the MCC and possibly other genes are involved in the progression of immortalization.
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Type
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dissertation
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Source
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PQT Legacy CUNY.xlsx
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degree
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Ph.D.
