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9-Hydroxyellipticine alters the conformation and DNA binding characteristics of mutated p53 protein
E Sugikawa1, S Tsunoda, N Nakanishi
1Discovery Research Laboratory, Tanabe Seiyaku Co., Ltd., Toda, Saitama, Japan.
Abstract:
The tumor suppressor protein p53 is a phosphoprotein which shows growth and transformation suppression functions. Mutational loss of p53 function is the most frequently detected genetic event in human cancers. We examined whether 9-hydroxyellipticine (9HE), a cytotoxic agent, affected the tertiary structure of mutant p53 and DNA binding characteristics. Although several types of p53 mutants were resistant to degradation by calpain, the p53 mutants treated with 9HE were markedly sensitive to calpain as well as wild-type p53. Furthermore, mutant p53 proteins isolated from 9HE-treated cells regained the ability to bind a wild-type-specific p53 DNA consensus sequence. Wild-type p53 proteins prepared from both untreated and 9HE-treated cells bound the p53 consensus sequence and were degradaded by calpain equally well. These results suggest that 9HE affects the tertiary structure of mutated p53, which results in the restoration of DNA binding characteristics.
Insights
The cytotoxic agent 9-hydroxyellipticine (9HE) restores tumor suppressor protein p53
Area of Science:
- Oncology
- Molecular Biology
- Biochemistry
Background:
- The tumor suppressor protein p53 is crucial for preventing cancer.
- Mutations in p53 are common in human cancers, leading to loss of its tumor-suppressing functions.
- Restoring p53 function is a key therapeutic goal in cancer treatment.
Purpose of the Study:
- To investigate the effect of 9-hydroxyellipticine (9HE) on the tertiary structure and DNA binding of mutant p53.
- To determine if 9HE can restore wild-type-like functions to mutated p53 proteins.
Main Methods:
- Treatment of cancer cells with 9HE.
- Analysis of p53 protein stability and degradation by calpain.
- Assessment of p53 DNA binding affinity to a consensus sequence.
Main Results:
- Mutant p53 proteins, normally resistant to calpain degradation, became sensitive after 9HE treatment.
- 9HE treatment restored the ability of mutant p53 to bind to a wild-type p53 DNA consensus sequence.
- Wild-type p53 showed consistent calpain sensitivity and DNA binding regardless of 9HE treatment.
Conclusions:
- 9-hydroxyellipticine (9HE) alters the tertiary structure of mutant p53.
- This structural change restores the DNA binding capacity of mutant p53, suggesting a potential therapeutic strategy for cancers with p53 mutations.