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Suppression of the chemically transformed phenotype of BHK cells by a human cDNA
M V Eiden1, L MacArthur, H Okayama
1Laboratory of Cell Biology, National Institute of Mental Health, Bethesda, Maryland 20892.
Abstract:
Transformation of the baby hamster kidney cell line BHK SN-10 by chemical carcinogens such as nitrosylmethylurea (NMU) is mediated by the loss of a gene product critical for the suppression of malignant transformation. Somatic cell hybrids between chemically transformed BHK SN-10 cells and either normal hamster kidney or human fibroblast cells are nontransformed; therefore, a recessive mechanism underlies the malignant transformation of BHK SN-10 cells after chemical carcinogenesis (A. Stoler and N. P. Bouck, Proc. Natl. Acad. Sci. USA 82:570-574, 1985). A human fibroblast cDNA library was constructed and introduced into NMU-transformed BHK SN-10 cells (NMU 34m) in order to identify a human cDNA capable of suppressing cellular transformation. NMU-transformed BHK cells were analyzed for reversion to an anchorage-dependent normal cellular phenotype after transfection with human cDNA. The human cDNA capable of inducing stable reversion of NMU 34m cells encodes the intermediate filament protein vimentin, which is apparently required for maintenance of the normal phenotype in BHK SN-10 cells.
Insights
Chemicals cause malignant transformation in baby hamster kidney cells by losing a gene product. Introducing human vimentin cDNA reversed this transformation, revealing its role in maintaining normal cell phenotype.
Area of Science:
- Cell Biology
- Molecular Biology
- Cancer Research
Background:
- Chemical carcinogens like nitrosylmethylurea (NMU) induce malignant transformation in baby hamster kidney (BHK) SN-10 cells.
- This transformation is linked to the loss of a gene product crucial for suppressing malignancy.
- Somatic cell hybridization studies indicated a recessive mechanism underlying this malignant transformation.
Purpose of the Study:
- To identify a human cDNA capable of suppressing cellular transformation in NMU-transformed BHK SN-10 cells.
- To investigate the genetic basis of malignant transformation and identify suppressor genes.
Main Methods:
- Construction of a human fibroblast cDNA library.
- Transfection of NMU-transformed BHK SN-10 cells (NMU 34m) with the human cDNA library.
- Analysis of transfected cells for reversion to a normal, anchorage-dependent phenotype.
Main Results:
- A specific human cDNA was identified that induced stable reversion of the transformed phenotype in NMU 34m cells.
- This cDNA encodes the intermediate filament protein vimentin.
- Vimentin appears to be essential for maintaining the normal cellular phenotype in BHK SN-10 cells.
Conclusions:
- Malignant transformation of BHK SN-10 cells by NMU involves the loss of vimentin's function.
- Reintroduction of vimentin can restore the normal, non-transformed cellular phenotype.
- Vimentin plays a critical role in suppressing or maintaining the normal phenotype in this cell line.