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Sensitivity to ionizing radiation in Saos-2 cells transfected with mutant p53 genes depends on the mutation position
1Department of Radiation Biophysics, Nagasaki University School of Medicine, Japan. okaichi@net.nagasaki-u.ac.jp
Abstract:
We have constructed an in vitro system to examine how p53 mutants affect radiosensitivity. Mutations of p53 were made using in vitro mutagenesis, and mutant cDNAs were introduced into the human osteosarcoma cell line, Saos-2, which is devoid of endogenous p53. For wild type p53, both the expression plasmid and a regulation plasmid (LacSwitch system) were transfected into the cells. The radiosensitivities of clones of mutant p53 and wild type p53 were examined. Transformants of wild type p53 had increased radiosensitivity. The induction of wild type p53 protein by addition of IPTG did not significantly increased radiosensitivity. A mutation at codon 123 also increased radiosensitivity. Mutations at codons 143, 175, and 273 did not alter radiosensitivity.
Insights
This study investigated how p53 mutations impact radiosensitivity using an in vitro system. Wild type p53 increased radiosensitivity, while specific mutations showed varied effects.
Area of Science:
- Molecular Biology
- Cancer Research
- Genetics
Background:
- The tumor suppressor protein p53 plays a crucial role in cellular response to DNA damage.
- Understanding how p53 mutations affect cellular radiosensitivity is vital for cancer therapy.
- The Saos-2 cell line, lacking endogenous p53, provides a suitable model for studying p53 function.
Purpose of the Study:
- To establish an in vitro system for analyzing the impact of p53 mutants on radiosensitivity.
- To determine the effect of wild type p53 and various p53 mutants on the radiosensitivity of Saos-2 cells.
Main Methods:
- In vitro mutagenesis was used to create p53 mutants.
- Mutant and wild type p53 cDNAs were introduced into Saos-2 cells via transfection.
- The LacSwitch system was employed for regulating p53 expression.
- Radiosensitivity of transfected cell clones was assessed.
Main Results:
- Transfection with wild type p53 led to increased radiosensitivity in Saos-2 cells.
- Induction of wild type p53 protein with IPTG did not significantly alter radiosensitivity.
- A mutation at codon 123 of p53 also resulted in increased radiosensitivity.
- Mutations at codons 143, 175, and 273 did not significantly affect radiosensitivity.
Conclusions:
- Wild type p53 expression enhances cellular radiosensitivity.
- Specific p53 mutations, such as at codon 123, can also increase radiosensitivity.
- Other p53 mutations (codons 143, 175, 273) do not appear to influence radiosensitivity in this model system.