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C127 cells resistant to transformation by tyrosine protein kinase oncogenes
A Cuadrado1, N Talbot, M Barbacid
1Developmental Oncology Section, National Cancer Institute-Frederick Cancer Research Facility, Maryland 21701.
Abstract:
C127 is a nontumorigenic mouse cell line widely used in in vitro transformation assays due to its normal morphological appearance and its very low levels of spontaneous transformation. We now report that C127 cells are resistant to transformation by tyrosine protein kinase oncogenes derived from growth factor receptors such as the retroviral v-fms and the human trk transforming genes. In contrast, these cells could be efficiently transformed by members of the ras oncogene family and by serine/threonine kinase oncogenes such as v-mos and v-raf. C127 cells were also found to be resistant to transformation by v-src, the prototype of a large family of tyrosine protein kinase oncogenes whose products are associated with the inner side of the plasma membrane. However, morphologically normal C127 cells expressing pp60v-src acquired a transformed phenotype upon continuous passage in vitro. Somatic cell hybrids (neoR, hygroR) obtained by fusion of G418-resistant C127 cells expressing p70trk (neoR) and hygromycin-resistant NIH3T3 cells (hygroR) exhibited transformed properties as determined by their ability to grow in semisolid agar. In contrast, no such growth was observed when these neoR p70trk-containing C127 cells were fused to control hygroR C127 cells. These results indicate that C127 cells may either lack or express insufficient levels of certain critical substrate(s) necessary for the onset of transformation by tyrosine protein kinase oncogenes.
Insights
C127 mouse cells resist transformation by certain oncogenes but can be transformed by others. This resistance is linked to insufficient substrates for tyrosine protein kinase oncogenes.
Area of Science:
- Cell biology
- Molecular oncology
- Cancer research
Background:
- C127 cells are a standard nontumorigenic mouse cell line for in vitro transformation assays.
- They exhibit normal morphology and low spontaneous transformation rates, making them suitable for studying oncogene-induced transformation.
Purpose of the Study:
- To investigate the susceptibility of C127 cells to transformation by different classes of oncogenes.
- To elucidate the molecular mechanisms underlying C127 cell resistance or sensitivity to specific oncogenes.
Main Methods:
- Transformation assays using various oncogenes, including tyrosine protein kinase (v-fms, trk, v-src) and serine/threonine kinase (v-mos, v-raf) oncogenes.
- Generation and analysis of somatic cell hybrids between C127 and NIH3T3 cells.
- Assessment of transformed phenotypes, including growth in semisolid agar.
Main Results:
- C127 cells demonstrated resistance to transformation by tyrosine protein kinase oncogenes (v-fms, trk, v-src).
- Efficient transformation occurred with ras oncogenes and serine/threonine kinase oncogenes (v-mos, v-raf).
- C127 cells expressing pp60v-src acquired a transformed phenotype after prolonged in vitro passage.
- Somatic cell hybrids of C127 and NIH3T3 cells expressing p70trk showed transformed properties, unlike hybrids with control C127 cells.
Conclusions:
- C127 cells possess intrinsic resistance to transformation mediated by specific tyrosine protein kinase oncogenes.
- This resistance is likely due to a deficiency or low expression of essential substrate(s) for these oncogenes.
- The findings highlight the importance of specific cellular substrates in oncogenic transformation pathways.