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Macromolecular changes accompanying immortalization and tumorigenic conversion in a human fibroblast model system
1Armand Hammer Cancer Research Center, Linus Pauling Institute of Science and Medicine, Palo Alto, CA 94306.
Mutation Research
|June 1, 1988
Summary
Chemical carcinogen mutagenesis of human fibroblasts created immortalized strains. Mutant beta-actin expression correlated with tumorigenicity and altered gene expression, impacting cell morphology and cancer potential.
Area of Science:
- Cell Biology
- Molecular Biology
- Cancer Research
Background:
- Diploid human fibroblast strain KD was mutagenized using 4-nitroquinolin-1-oxide.
- This process yielded several stably immortalized neoplastic substrains.
Purpose of the Study:
- Characterize four transformed substrains (HuT-11, -12, -13, -14) focusing on morphology and gene expression changes.
- Investigate the role of beta-actin mutations in tumorigenicity and cellular transformation.
Main Methods:
- Chemical mutagenesis of human fibroblasts.
- Isolation and characterization of immortalized substrains.
- Gene expression analysis and gene transfection studies.
Main Results:
- HuT-11, -12, -13 were immortalized but non-tumorigenic; HuT-14 was immortalized and tumorigenic.
- HuT-14 exhibited a defective beta-actin due to a point mutation.
- All HuT strains showed altered expression of plastin, EGF-related polypeptides, and tropomyosin isoforms.
- Transfection of mutant beta-actin into KD and HuT cells induced morphological changes and, in HuT-12, increased tumorigenicity and tropomyosin switching.
Conclusions:
- Mutant beta-actin expression is linked to increased tumorigenicity and specific gene expression changes in human fibroblasts.
- Altered expression of beta-actin, plastin, EGF-related polypeptides, and tropomyosin isoforms are key events in neoplastic transformation.