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[mRNA breakdown in tumor cells in vivo under cycloheximide protein synthesis inhibition]
Abstract:
Amoung of prelabelled mRNA was unaltered in Zajhdel ascites hepatoma of rat cells within 3.5-4 hrs under conditions of treatment with actinomycin D. Due to combined effect of actinomycin D and cycloheximide the content of mRNA in the hepatoma cells was rapidly decreased. Degradation of mRNA occurred in membrane-bound polyribosomes, free polyribosomes and in cytoplasmic mRNP-particles /informosomes/ as a result of the effect of cycloheximide. Simultaneously with these phenomena, distinct increase in activity of acid and alkaline RNAases was observed in cytoplasma of the hepatoma cells; activity of endoRNAase from membrane-bound and free polyribosomes of the hepatoma was also markedly increased. Cycloheximide did not affect the activity of polynucleotide phosphorylase in polyribosomes of the hepatoma cells. Labile proteins, responsible for inhibition of RNAses appeart to participate in regulation of mRNA stability in malignant cells.
Insights
Actinomycin D alone did not affect prelabelled messenger RNA (mRNA) in rat hepatoma cells. However, combined with cycloheximide, it rapidly decreased mRNA levels, indicating protein involvement in mRNA stability.
Area of Science:
- Molecular Biology
- Biochemistry
- Cancer Research
Context:
- Investigating messenger RNA (mRNA) stability in Zajdela ascites hepatoma cells.
- Examining the effects of actinomycin D and cycloheximide on mRNA metabolism.
Purpose:
- To determine the impact of actinomycin D and cycloheximide on mRNA levels and degradation pathways in hepatoma cells.
- To elucidate the role of specific enzymes and proteins in regulating mRNA stability in malignant cells.
Summary:
- Actinomycin D alone did not alter prelabelled mRNA levels in rat hepatoma cells within 3.5-4 hours.
- Combined treatment with actinomycin D and cycloheximide led to a rapid decrease in mRNA content.
- Cycloheximide induced mRNA degradation in membrane-bound polyribosomes, free polyribosomes, and cytoplasmic mRNP-particles (informosomes).
- This degradation was accompanied by increased activity of acid and alkaline RNAases in the cytoplasm and endoRNAase activity in polyribosomes.
- Cycloheximide did not affect polynucleotide phosphorylase activity in hepatoma cell polyribosomes.
- The findings suggest that labile proteins, which inhibit RNAases, play a crucial role in regulating mRNA stability in malignant cells.
Impact:
- Highlights the role of protein factors in mRNA stability within cancer cells.
- Provides insights into the mechanisms of mRNA degradation in hepatoma.
- Suggests potential targets for therapeutic intervention aimed at modulating mRNA stability in cancer.