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Differential response to cytochalasin B among cells transformed by DNA and RNA tumor viruses
Abstract:
Mouse, hamster, rat, human, and chick cells were transformed by RNA and DNA tumor viruses: simian virus 40, adenovirus type 7, Kirsten mouse sarcoma virus (Ki-MuSV), Moloney mouse sarcoma virus, and Rous sarcoma virus. All cultures of transformed cells grew to high concentration densities. Normal and transformed cells were treated with cytochalasin B (CB) at concentrations preventing cytoplasmic cleavage. Cells altered by DNA tumor viruses responded to CB with numerous nuclear divisions resulting in highly multinucleated cells. All but one line of cells transformed by RNA tumor viruses responded to CB with usually only one and occasionally two nuclear divisions. Only binucleated cells were formed. One clone of CB-treated BALB/c mouse embryo fibroblasts transformed by Ki-MuSV showed numerous cells with four and five nuclei. HOWEVER, IN CONTRASt to cells transformed by DNA viruses, few cells had seven or more nuclei. These results suggest that, in the presence of CB, cells transformed by DNA tumor viruses show uncontrolled nuclear division, whereas cells tranformed by RNA tumor viruses show controlled nuclear division.
Insights
DNA and RNA tumor viruses induce distinct cell division patterns. DNA virus-transformed cells exhibit uncontrolled nuclear division, while RNA virus-transformed cells show controlled nuclear division when treated with cytochalasin B.
Area of Science:
- Cell Biology
- Virology
- Cancer Research
Background:
- Tumor viruses, both RNA and DNA types, are known to transform cells.
- Understanding the distinct cellular responses to these virus types is crucial for cancer research.
Purpose of the Study:
- To investigate the differential effects of RNA and DNA tumor viruses on cell division regulation.
- To compare the multinucleation patterns induced by cytochalasin B in cells transformed by different tumor viruses.
Main Methods:
- Cells from mouse, hamster, rat, human, and chick were transformed by various RNA and DNA tumor viruses.
- Transformed and normal cells were treated with cytochalasin B (CB) to inhibit cytoplasmic cleavage.
- Nuclear division patterns were analyzed in CB-treated cells.
Main Results:
- Cells transformed by DNA tumor viruses showed numerous nuclear divisions, leading to highly multinucleated cells in the presence of CB.
- Cells transformed by RNA tumor viruses generally exhibited limited nuclear divisions (one or two), forming predominantly binucleated cells.
- A notable exception was a clone transformed by Kirsten mouse sarcoma virus (Ki-MuSV), which showed multiple nuclei but fewer cells with seven or more nuclei compared to DNA virus-transformed cells.
Conclusions:
- DNA tumor virus transformation leads to uncontrolled nuclear division in the presence of CB.
- RNA tumor virus transformation results in controlled nuclear division, suggesting distinct regulatory mechanisms.
- These findings highlight differences in cellular responses to RNA vs. DNA tumor virus oncogenes.