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Cell immortalization as a key, rate-limiting event in malignant transformation: approaches toward a molecular genetic
R F Newbold1, A P Cuthbert, M Themis
1Department of Biology and Biochemistry, University of West London, Uxbridge, Middlesex, UK.
Abstract:
Recent advances using somatic cell genetic approaches have provided a convincing body of evidence that the senescence of mammalian cells in culture is controlled by a small group of genes, one or more of which are functionally deleted in the process of immortalization. Microcell-mediated mono-chromosomal transfer methods should permit precise mapping of these genes to specific chromosomal regions. Cloning of senescence genes, using either conventional 'positional cloning' techniques or retroviral insertion mutagenesis, is now a realistic possibility. The leap in our understanding of the molecular genetic events driving the alternative cellular states of limited proliferative capacity and immortality, which such advances should precipitate, will finally permit the question of the role of cell immortalization in cancer to be addressed, and may open the door to the design of new modes of cancer therapy. In addition, the precise mechanism underlying the wide difference in transformability between human and rodent cells, which should also emerge from these investigations, is likely to make a significant contribution towards resolving the key issue of the relevance of rodent tumour induction assays in assessing the potential carcinogenicity of environmental chemicals.
Insights
Cellular senescence is controlled by specific genes, with some deleted during immortalization. Understanding these senescence genes could advance cancer therapy and chemical carcinogenicity assessments.
Area of Science:
- Cell Biology
- Genetics
- Cancer Research
Background:
- Cellular senescence limits cell proliferation, a key factor in aging and tumor suppression.
- Cell immortalization involves the loss of proliferative control, often linked to genetic alterations.
- Understanding the genetic basis of senescence and immortalization is crucial for cancer research.
Purpose of the Study:
- To identify and map genes controlling mammalian cellular senescence.
- To elucidate the molecular mechanisms underlying cellular immortalization.
- To investigate the role of cell immortalization in cancer development and human vs. rodent cell transformability.
Main Methods:
- Somatic cell genetic approaches to identify senescence-controlling genes.
- Microcell-mediated mono-chromosomal transfer for gene mapping.
- Positional cloning and retroviral insertion mutagenesis for gene isolation.
Main Results:
- Evidence suggests a small set of genes controls cellular senescence.
- Functional deletion of senescence genes is implicated in cell immortalization.
- Gene mapping to specific chromosomal regions is feasible with current methods.
Conclusions:
- Advances in senescence gene identification will deepen understanding of cell immortalization.
- This knowledge may lead to novel cancer therapies.
- Investigating differences in cell transformability can inform chemical carcinogenicity testing.