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Stepwise transformation of primary thyroid epithelial cells by a mutant Ha-ras oncogene: an in vitro model of tumor progression

Stepwise transformation of primary thyroid epithelial cells by a mutant Ha-ras oncogene: an in vitro model of tumor progression
Stepwise transformation of primary thyroid epithelial cells by a mutant Ha-ras oncogene: an in vitro model of tumor progression
Activating mutations of the ras oncogene family occur at high frequency in all stages of thyroid tumorigenesis, both human and experimental. To test the causal nature of this association, and to investigate the biological role of ras mutation, we introduced a mutant c-Ha-ras gene into
normal rat thyroid follicular cells using an ecotropic retroviral vector. The major immediate effect was to greatly extend the proliferative lifespan of these cells in culture from less than 3 to more than 15 doublings, without any observable loss of growth-factor dependence or differentiated functions. This in vitro phenotype strongly supports an initiating role for ras mutation in the genesis of benign thyroid tumors (adenomas) in vivo. Spontaneous transformation was observed at low frequency on continuous culture of mutant ras-expressing cells, giving rise to fully immortalized, growth factor-independent, highly tumorigenic lines. Transformation was associated with (i) loss of responsiveness to the growth inhibitor TGF-beta 1, and (ii) greatly increased nuclear levels of p53 protein, which unexpectedly was not due to point mutation in the conserved regions of the p53-coding sequence. We postulate that these two phenomena are causally related to each other and to the transformed phenotype.
p53, TGF-?, tumor suppressor genes
0899-1987
129-139
Burns, Jorge S.
7795b30a-03a0-4f20-8b6c-57127aa02b68
Blaydes, Jeremy P.
e957f999-fd91-4f77-ad62-5b4ef069b15b
Wright, Pat A.
709c2450-0ba8-4c0d-a16f-d27ec0ed472b
Lemoine, Louise
dd0c27a8-77ea-4376-b932-90e4222cfa2a
Bond, Jane A.
b01d114f-378a-47be-89e3-e8411356ebd7
Williams, E. Dillwyn
1170d9ca-ecf4-4b3a-a4d9-54d1749720e6
Wynford-Thomas, D.
e2abffc0-8c45-4681-b36b-6f1e0fba8ec7
Burns, Jorge S.
7795b30a-03a0-4f20-8b6c-57127aa02b68
Blaydes, Jeremy P.
e957f999-fd91-4f77-ad62-5b4ef069b15b
Wright, Pat A.
709c2450-0ba8-4c0d-a16f-d27ec0ed472b
Lemoine, Louise
dd0c27a8-77ea-4376-b932-90e4222cfa2a
Bond, Jane A.
b01d114f-378a-47be-89e3-e8411356ebd7
Williams, E. Dillwyn
1170d9ca-ecf4-4b3a-a4d9-54d1749720e6
Wynford-Thomas, D.
e2abffc0-8c45-4681-b36b-6f1e0fba8ec7

Burns, Jorge S., Blaydes, Jeremy P., Wright, Pat A., Lemoine, Louise, Bond, Jane A., Williams, E. Dillwyn and Wynford-Thomas, D. (1992) Stepwise transformation of primary thyroid epithelial cells by a mutant Ha-ras oncogene: an in vitro model of tumor progression. Molecular Carcinogenesis, 6 (2), 129-139. (doi:10.1002/mc.2940060208).

Record type: Article

Abstract

Activating mutations of the ras oncogene family occur at high frequency in all stages of thyroid tumorigenesis, both human and experimental. To test the causal nature of this association, and to investigate the biological role of ras mutation, we introduced a mutant c-Ha-ras gene into
normal rat thyroid follicular cells using an ecotropic retroviral vector. The major immediate effect was to greatly extend the proliferative lifespan of these cells in culture from less than 3 to more than 15 doublings, without any observable loss of growth-factor dependence or differentiated functions. This in vitro phenotype strongly supports an initiating role for ras mutation in the genesis of benign thyroid tumors (adenomas) in vivo. Spontaneous transformation was observed at low frequency on continuous culture of mutant ras-expressing cells, giving rise to fully immortalized, growth factor-independent, highly tumorigenic lines. Transformation was associated with (i) loss of responsiveness to the growth inhibitor TGF-beta 1, and (ii) greatly increased nuclear levels of p53 protein, which unexpectedly was not due to point mutation in the conserved regions of the p53-coding sequence. We postulate that these two phenomena are causally related to each other and to the transformed phenotype.

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More information

Published date: 20 July 1992
Keywords: p53, TGF-?, tumor suppressor genes

Identifiers

Local EPrints ID: 150593
URI: https://eprints.soton.ac.uk/id/eprint/150593
ISSN: 0899-1987
PURE UUID: 5ae34eb5-e8bf-45eb-b88b-3acf4cd0c1fa
ORCID for Jeremy P. Blaydes: ORCID iD orcid.org/0000-0001-8525-0209

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Date deposited: 16 Jun 2010 10:33
Last modified: 18 May 2019 00:36

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