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[Identification of a specific protein in flat revertant cell lines derived from ras oncogene-transformed cells]
1Laboratory of Molecular Genetics, Hokkaido University, School of Medicine, Sapporo, Japan.
Abstract:
Total proteins from a mouse embryo fibroblast cell line NIH/3T3, NIH/3T3 cells transformed by human activated c-Ha-ras (EJ-ras) oncogene (EJ-NIH/3T3), and the two flat revertant cell lines, R1 and R2 were analyzed by two-dimensional gel electrophoresis (IEF and NEPHGE). Several hundred polypeptides were resolved as seen by silver staining. Common alterations in four polypeptide spots were observed in the revertants when compared with NIH/3T3 and EJ-NIH/3T3 cells. In these alterations, a new polypeptide spot p92-5.7 (designated by molecular weight X 10(-3) and pI) was detected only in the revertants, but not in NIH/3T3 and EJ-NIH/3T3 cells. Furthermore, the expression level of p92-5.7 seemed to be associated with the flat morphology and the reduced tumorigenicity of the revertants. The polypeptide p92-5.7 was also not detected in the total proteins extracted from BALB/3T3 cells, NIH Swiss mouse primary embryo fibroblasts. Subcellular fractionation of total protein from R1 cells revealed that the p92-5.7 was present in the cytosol. The p92-5.7 was not phosphorylated in the steady state of R1 cells. Western blot analysis using an anti-gelsolin antibody demonstrated that the p92-5.7 might be a variant form of gelsolin which is thought to be an actin regulatory protein or a gelsolin-like polypeptide. The expressions of gelsolin mRNA in the revertants were higher than in the EJ-NIH/3T3 cells. These results may suggest that the expression of p92-5.7 detected only in the revertants is associated, at least in part, with the reversion. This may be the first demonstration of the specific protein expression in the flat revertants.
Insights
Researchers identified a novel protein, p92-5.7, exclusively in flat revertant cancer cells. This protein, potentially a gelsolin variant, correlates with reduced cell malignancy and may play a role in cancer reversion.
Area of Science:
- Molecular Biology
- Cell Biology
- Cancer Research
Context:
- Investigated protein expression differences between normal, oncogene-transformed, and revertant mouse fibroblast cell lines.
- Utilized two-dimensional gel electrophoresis (IEF and NEPHGE) for high-resolution polypeptide analysis.
- Focused on identifying specific protein alterations associated with phenotypic reversion.
Purpose:
- To identify novel protein markers associated with the reversion of oncogene-induced cellular transformation.
- To characterize the expression and potential function of a newly detected polypeptide (p92-5.7) in flat revertant cells.
- To explore the relationship between p92-5.7 expression and cellular morphology and tumorigenicity.
Summary:
- A unique polypeptide, p92-5.7, was detected exclusively in flat revertant cell lines (R1 and R2) but not in NIH/3T3 or EJ-NIH/3T3 cells.
- p92-5.7 expression levels correlated with the flat morphology and reduced tumorigenicity of the revertant cells.
- Western blot analysis suggested p92-5.7 is a variant or gelsolin-like protein, with higher gelsolin mRNA expression observed in revertants.
Impact:
- This study presents the first specific protein expression profile identified in flat revertant cells.
- The findings suggest that p92-5.7 may be a key molecular indicator of cellular reversion from oncogenic transformation.
- Identifies a potential therapeutic target or biomarker for understanding and potentially reversing cancer progression.