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Altered growth response of oral mucosal keratinocytes in p53-deficient mice
1Second Department of Oral and Maxillofacial Surgery, School of Dentistry, Showa University, Tokyo, Japan.
Abstract:
P53 has important regulatory functions in cell growth, differentiation and apoptosis. Here we analyzed the effects of p53 on the growth response of oral mucosal keratinocytes (OMKCs) using p53-deficient (p53-/-) mice. No morphological difference was found between p53-/- and wild-type (p53+/+) oral mucosa. In a long-term culture, p53-/- OMKCs continued to proliferate past the point at which p53+/+ became senescent. The percentage of p53-/- OMKCs in the G0/G1 phase was lower than that of p53+/+ OMKCs. Proliferation of cultured OMKCs induced by epidermal growth factor (EGF) and interleukin-(IL)-1alpha was more strongly enhanced in p53-/- than in p53+/+ mice. Such an enhanced response was not due to increased mRNA expression of growth factor receptors. These data suggest that p53 acts as a modulator of G1 arrest in OMKCs and is also involved in the regulation of responses to EGF and IL-1alpha without affecting the expression of their receptors.
Insights
The tumor suppressor p53 regulates cell growth and prevents senescence. P53 deficiency in oral mucosal keratinocytes (OMKCs) enhances proliferation and response to growth factors like EGF and IL-1alpha.
Area of Science:
- Molecular Biology
- Cell Biology
- Oncology
Background:
- The p53 protein is a critical regulator of cell cycle arrest, differentiation, and apoptosis.
- Understanding p53's role in oral mucosal keratinocytes (OMKCs) is vital for oral cancer research.
Purpose of the Study:
- To investigate the impact of p53 deficiency on OMKC proliferation and growth factor response.
- To elucidate p53's function in modulating G1 arrest and growth factor signaling pathways.
Main Methods:
- Utilized p53-deficient (p53-/-) and wild-type (p53+/+) mice for oral mucosa analysis.
- Performed long-term cell culture of OMKCs to assess senescence and proliferation.
- Quantified cell cycle distribution using flow cytometry.
- Assessed OMKC proliferation in response to epidermal growth factor (EGF) and interleukin-1alpha (IL-1alpha).
Main Results:
- No significant morphological differences were observed between p53-/- and p53+/+ oral mucosa.
- p53-/- OMKCs exhibited extended proliferation and delayed senescence compared to p53+/+ OMKCs.
- p53-/- OMKCs showed a reduced percentage in the G0/G1 phase.
- Proliferation induced by EGF and IL-1alpha was significantly enhanced in p53-/- OMKCs, independent of growth factor receptor expression.
Conclusions:
- p53 functions as a key modulator of G1 arrest in OMKCs.
- p53 plays a role in regulating the cellular response to EGF and IL-1alpha without altering receptor expression levels.
- These findings highlight p53's importance in controlling oral epithelial cell proliferation and response to mitogenic stimuli.