onr:"swepub:oai:DiVA.org:umu-33466"
Search: onr:"swepub:oai:DiVA.org:umu-33466" > The immortalization...
- 1 of 1
- Previous record
- Next record
- To hitlist
The immortalization process of T cells : with focus on the regulation of telomere length and telomerase activity
-
- Degerman, Sofie, 1977- (author)
- Umeå universitet,Patologi
-
- Roos, Göran, Professor (thesis advisor)
- Umeå universitet,Patologi
-
- Sedivy, John, Professor (opponent)
- Department of Molecular Biology, Cell Biology and Biochemistry, Brown University, RI, USA
- (creator_code:org_t)
- ISBN 9789174590074
- Umeå : Umeå university, 2010
- English 60 s.
- Series: Umeå University medical dissertations, 0346-6612 ; 1347
- Doctoral thesis (other academic/artistic)
Abstract
Subject headings
Close
- Cellular immortalization is a major hallmark of cancer and is a multi-step process that requires numerous cell-type specific changes, including inactivation of control mechanisms and stabilization of telomere length. The telomeres at the chromosome ends are essential for genomic stability, and limit the growth potential of most cells. With each cell division, telomeres are shortened. Short telomeres may induce an irreversible growth arrest stage called senescence, or a growth crisis stage characterized by high genomic instability and cell death. Only very rarely do cells escape from crisis and become immortal, a stage that has been associated with the activation of the telomerase enzyme which can elongate and stabilize the telomeres. The processes leading to senescence bypass, growth crisis escape and finally immortalization are only beginning to be elucidated. Most of our knowledge of the immortalization process is based on analyses of human fibroblast and epithelial cell cultures immortalized by genetic modification. In this thesis, spontaneously immortalized human T lymphocytes derived from patients with Nijmegen Breakage Syndrome and a healthy individual were used to identify critical events for senescence bypass and immortalization. Genetic analysis showed a clonal progression and non-random genetic changes including the amplification of chromosomal region 2p13-21 as an early event in the immortalization process. Telomere length gradually shortened at increasing population doublings and growth crisis was associated with critically short telomeres. The clone(s) that escaped growth crisis demonstrated a logarithmic growth curve, very short telomeres and, notably, no increase in telomerase activity or expression of the telomerase catalytic gene, hTERT. Instead, upregulation of telomerase activity and telomere length stabilization were late events in T lymphocyte immortalization. Escape from crisis was associated with downregulation of DNA damage response genes and altered expression of cell cycle regulators and genes controlling the cellular senescence program. These data indicated that a number of layers of regulation are important in the process of immortalization and to provide further mechanistic detail, epigenetic analysis was carried out. Genome wide methylation array analysis identified early and step-wise methylation changes during the immortalization process. Interestingly, applying these findings to tumors of T cell origin revealed commonly methylated CpG sites in transformed cells. Deregulated gene expression of the polycomb complexes may have contributed to the epigenetic changes observed. Taken together, our analysis of spontaneously immortalized T cell cultures identified several steps in the immortalization process including genetic, epigenetic, gene expression and telomere/telomerase regulatory events, contributing further insights to the complexity of cancer cell immortalization.
Keyword
- immortalization
- senescence
- T cells
- Nijmegen breakage syndrome
- telomere
- telomerase
- hTERT
- generic aberrations
- methylation
- MEDICINE
- MEDICIN
- Pathology
- patologi
Publication and Content Type
- vet (subject category)
- dok (subject category)
Find in a library
- The immortalization process of T cells with focus on the regulation of telomere ... (Search the publication in LIBRIS)
To the university's database
- 1 of 1
- Previous record
- Next record
- To hitlist
Find more in SwePub
- By the author/editor
- Degerman, Sofie, ...
- Roos, Göran, Pro ...
- Sedivy, John, Pr ...
- Parts in the series
- Umeå University ...
- By the university
- Umeå University
Search outside SwePub
- Extend your search to:
- Google Book Search
- Google Scholar
Kungliga biblioteket hanterar dina personuppgifter i enlighet med EU:s dataskyddsförordning (2018), GDPR. Läs mer om hur det funkar här.
Så här hanterar KB dina uppgifter vid användning av denna tjänst.
- Copyright © LIBRIS - National Library Systems
- LIBRIS.kb.se
