Polyadenylated RNA molecules and polyribosomes in tumours of chemical and viral origin
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Abstract:
The distribution of poly(A)-enriched mRNA in nuclei, mitochondira, free and membrane-bound polyribosomes from normal C3HA mouse and Syrian hamster livers and normal chicken fibroblasts has been compared with that in corresponding subcellular fractions in a transplantable, chemically induced MD hepatoma, non-virus-producer hamster and virus-producer chicken Rous sarcomas. It has been shown that the content of poly(A)-RNA is increased in all tumour fractions except in free polyribosomes. The distribution of different classes of polysomes i.e. free, membrane-bound and mitochondrial outer-membrane-associated polysomes in tumour cells was changed in comparison to that in normal cells. It is concluded that in tumours of chemical and viral origin, the observed changes in the two components of the protein-synthesizing apparatus occur simultaneously.
Insights
Tumor cells show altered poly(A)-RNA distribution in subcellular fractions, with increased levels in most fractions except free polyribosomes. These changes in protein-synthesis components occur simultaneously in chemical and viral tumors.
Area of Science:
- Molecular Biology
- Cell Biology
- Biochemistry
Background:
- Polyadenylated RNA (poly(A)-RNA) plays a crucial role in mRNA stability and translation.
- Changes in poly(A)-RNA distribution and polysome profiles are associated with cellular transformation and tumorigenesis.
Purpose of the Study:
- To compare the distribution of poly(A)-enriched mRNA and polysomes in normal cells versus tumor cells.
- To investigate alterations in subcellular fractions of chemically induced and virally induced tumors.
Main Methods:
- Comparative analysis of poly(A)-RNA content in nuclear, mitochondrial, free, and membrane-bound polyribosome fractions.
- Examination of polysome distribution (free, membrane-bound, mitochondrial) in normal and tumor cells.
Main Results:
- Poly(A)-RNA content was elevated in most tumor fractions, excluding free polyribosomes.
- Significant shifts in the distribution of free, membrane-bound, and mitochondrial polysomes were observed in tumor cells compared to normal cells.
Conclusions:
- Tumors of both chemical and viral origin exhibit simultaneous alterations in poly(A)-RNA content and polysome organization.
- These coordinated changes suggest a fundamental disruption of the protein-synthesizing machinery in cancer cells.