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Characterization of c-myc-transformed rat fibroblasts resistant to apoptosis induced ny growth factor deprivation
S N Dhanaraj1, A M Marcus, R M Korah
1Department of Microbiology and Molecular Genetics, UMDNJ-New Jersey Medical School, 07103-2714, USA.
Abstract:
Under appropriate conditions (e.g., growth factor withdrawal), the deregulated expression of c-myc in rodent fibroblasts leads to substantial cell death due to apoptosis. To better understand this process, we selected for c-myc-transformed Rat1A fibroblasts that were resistant to growth factor deprivation-induced cell death. One clonal isolate exhibited prolonged survival in serum-free medium and displayed reduced levels of apoptosis-related DNA fragmentation. These cells were also resistant to induction of apoptosis by the protein kinase inhibitor staurosporine. They retained a transformed cell phenotype and expressed the proviral human c-myc allele in an unaltered fashion, strongly indicating that the mutation of a cellular gene other than c-myc accounts for the apoptosis-resistant phenotype. The results of somatic cell hybrid analysis of this cell line are consistent with a recessive mutation. Our findings suggest a novel mechanism for abrogation of apoptosis in neoplastic cells and provide a model system for the study of its role in tumorigenesis and resistance to antineoplastic therapy.
Insights
Researchers identified apoptosis-resistant cancer cells by selecting for c-myc-transformed fibroblasts. These cells provide a model to study how cancer cells evade cell death, aiding in understanding tumorigenesis and therapy resistance.
Area of Science:
- Molecular Biology
- Cell Biology
- Cancer Research
Background:
- Deregulated c-myc expression in fibroblasts induces apoptosis under growth factor withdrawal.
- Understanding resistance to apoptosis is crucial for cancer research and therapy development.
Purpose of the Study:
- To identify and characterize c-myc-transformed fibroblasts resistant to apoptosis.
- To investigate the genetic basis of apoptosis resistance in neoplastic cells.
Main Methods:
- Selection of c-myc-transformed Rat1A fibroblasts resistant to growth factor deprivation.
- Assays for apoptosis-related DNA fragmentation and staurosporine-induced apoptosis.
- Somatic cell hybrid analysis to determine the genetic nature of the resistance.
Main Results:
- A clonal isolate displayed prolonged survival in serum-free medium with reduced apoptosis.
- These cells were resistant to staurosporine-induced apoptosis but maintained a transformed phenotype.
- Somatic cell hybrid analysis suggested a recessive mutation underlies the apoptosis-resistant phenotype.
Conclusions:
- A novel mechanism for apoptosis abrogation in neoplastic cells was identified.
- This apoptosis-resistant cell line serves as a model for studying tumorigenesis and antineoplastic therapy resistance.