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Updated: Jun 17, 2025
Yeast As a Chassis for Developing Functional Assays to Study Human P53
Published on: August 4, 2019
Synergistic rescue of temperature-sensitive p53 mutants by hypothermia and arsenic trioxide
Junhao Lu1, Lihong Chen1, Zainab Fatima1
1Department of Molecular Oncology, Moffitt Cancer Center, Tampa, Florida, USA.
Abstract:
The p53 tumor suppressor is inactivated by mutations in about 50% of tumors. Rescuing the transcriptional function of mutant p53 has potential therapeutic benefits. Approximately 15% of p53 mutants are temperature sensitive (TS) and regain maximal activity at 32°C. Proof of concept study showed that induction of 32°C hypothermia in mice restored TS mutant p53 activity and inhibited tumor growth. However, 32°C is the lower limit of therapeutic hypothermia procedures for humans. Higher temperatures are preferable but result in suboptimal TS p53 activation. Recently, arsenic trioxide (ATO) was shown to rescue the conformation of p53 structural mutants by stabilizing the DNA binding domain. We examined the responses of 17 frequently observed p53 TS mutants to functional rescue by temperature shift and ATO. The results showed that ATO only rescued mild p53 TS mutants with high basal activity at 37°C. Mild TS mutants showed a common feature of regaining significant activity at the semi-permissive temperature of 35°C and could be further stimulated by ATO at 35°C. TS p53 rescue by ATO was antagonized by the cellular redox mechanism and was rapidly reversible. Inhibition of glutathione (GSH) biosynthesis enhanced ATO rescue efficiency and sustained p53 activity after ATO washout. The results suggest that mild TS p53 mutants are uniquely responsive to functional rescue by ATO due to small thermostability deficits and inherent potential to regain active conformation. Combining mild hypothermia and ATO may provide an effective and safe procedure for targeting tumors with p53 TS mutations.
Insights
Restoring tumor suppressor p53 function in cancers is a therapeutic goal. Arsenic trioxide (ATO) combined with mild hypothermia shows promise for activating temperature-sensitive (TS) p53 mutants, especially mild ones.
Area of Science:
- Oncology
- Molecular Biology
- Cancer Therapeutics
Background:
- The p53 tumor suppressor is frequently mutated in human cancers, and restoring its function holds therapeutic potential.
- Temperature-sensitive (TS) p53 mutants, comprising about 15% of p53 mutations, can regain activity at reduced temperatures (e.g., 32°C).
- Arsenic trioxide (ATO) has shown promise in stabilizing p53 structural mutants, suggesting a potential therapeutic strategy.
Purpose of the Study:
- To investigate the efficacy of arsenic trioxide (ATO) and mild hypothermia in rescuing the function of various p53 temperature-sensitive (TS) mutants.
- To determine the optimal conditions for functional rescue of TS p53 mutants, focusing on mild mutants with residual activity at physiological temperatures.
Main Methods:
- Assessed the functional rescue of 17 different p53 TS mutants using a combination of temperature shifts and ATO treatment.
- Investigated the influence of cellular redox mechanisms, specifically glutathione (GSH) biosynthesis, on ATO-mediated p53 rescue.
- Evaluated the reversibility and duration of p53 activity following ATO treatment and washout.
Main Results:
- ATO effectively rescued only mild p53 TS mutants exhibiting significant basal activity at 37°C and optimal activity at 35°C.
- ATO further enhanced the activity of mild TS p53 mutants at 35°C, but this rescue was counteracted by cellular redox mechanisms and was reversible.
- Inhibiting glutathione (GSH) biosynthesis improved ATO rescue efficiency and prolonged the p53 activity after ATO withdrawal.
Conclusions:
- Mild TS p53 mutants are uniquely responsive to ATO-mediated functional rescue due to their limited thermostability deficits.
- Combining mild hypothermia (e.g., 35°C) with ATO presents a potentially effective and safe strategy for targeting tumors with specific p53 TS mutations.
- Modulating cellular redox balance, such as by inhibiting GSH synthesis, can enhance the efficacy and sustainability of ATO-based p53 reactivation therapies.
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