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Vanadate induces G2/M phase arrest in p53-deficient mouse embryo fibroblasts
Zhuo Zhang1, Fei Chen, Chuanshu Huang
1Pathology and Physiology Research Branch, National Institute for Occupational Safety and Health, Morgantown, West Virginia 26505, USA.
Abstract:
Vanadium compounds exert potent toxic and carcinogenic effects on a wide variety of biological systems. The mechanisms involved in their toxicity and carcinogenesis require investigation. Cell growth arrest and its regulation are important mechanisms in maintaining genomic stability and integrity in response to environmental stress. The p53 tumor suppressor plays a central role in the regulation of the normal cell cycle. To investigate the role of p53 in vanadate-induced cell growth arrest and its regulation, two cell lines--normal mouse embryo fibroblasts [p53(+/+)] and p53-deficient mouse embryo fibroblasts [p53(-/-)],--were used in this study. Flow cytometry was used to analyze cell growth arrest at G0/G1, S, or G2/M phase. Western blotting analysis was performed to determine several cell growth regulatory proteins. The results showed that in p53(-/-) cells vanadate induced G2/M phase arrest in a dose- and time-dependent manner without alteration of S phase. In p53(+/+) cells, vanadate treatment increased the S phase with no significant change in the G2/M phase. Furthermore, Western blotting results showed that in p53(-/-) cells vanadate caused cdc25C degradation and activation of phospho-cdc2 without alteration of the p21 level. In p53(+/+) cells, vanadate increased the expression of p21 and degraded cdc25A instead of cdc25C without any effect on cdc2. These results demonstrate that vanadate induced G2/M phase arrest in p53-deficient mouse embryo fibroblasts, and promoted S phase entry in p53 wild-type mouse embryo fibroblasts.
Insights
Vanadate induces cell cycle arrest differently based on p53 (a tumor suppressor) status. P53-deficient cells arrest at G2/M, while normal cells enter S phase, revealing p53
Area of Science:
- Toxicology
- Cell Biology
- Cancer Research
Background:
- Vanadium compounds are toxic and carcinogenic, necessitating investigation into their mechanisms.
- Cell cycle regulation, particularly by the p53 tumor suppressor, is crucial for genomic stability.
- Understanding p53's role in vanadate toxicity is key to deciphering cellular responses to environmental stress.
Purpose of the Study:
- To investigate the role of the p53 tumor suppressor in vanadate-induced cell growth arrest.
- To compare the effects of vanadate on cell cycle regulation in p53-proficient and p53-deficient cells.
Main Methods:
- Utilized two mouse embryo fibroblast cell lines: normal [p53(+/+)] and p53-deficient [p53(-/-)].
- Employed flow cytometry to analyze cell cycle distribution (G0/G1, S, G2/M phases).
- Performed Western blotting to assess levels of key cell cycle regulatory proteins.
Main Results:
- Vanadate induced G2/M phase arrest in p53(-/-) cells in a dose- and time-dependent manner.
- Vanadate treatment promoted S phase entry in p53(+/+) cells without affecting G2/M phase.
- In p53(-/-) cells, vanadate caused cdc25C degradation and phospho-cdc2 activation; in p53(+/+) cells, it increased p21 and degraded cdc25A.
Conclusions:
- Vanadate induces distinct cell cycle arrest patterns dependent on p53 status.
- P53 deficiency leads to vanadate-induced G2/M arrest, while p53 presence promotes S phase entry.
- These findings highlight the critical role of p53 in mediating cellular responses to vanadate toxicity.