Inhibiting p53 Acetylation Reduces Cancer Chemotoxicity

Area of Science:

• Oncology
• Molecular Biology
• Pharmacology

Background:

• Chemotherapy-induced bone marrow toxicity, particularly myelosuppression from drugs like doxorubicin, limits treatment efficacy.
• Unwanted p53 activation in healthy bone marrow cells contributes to this chemotoxicity, posing a significant clinical challenge.

Purpose of the Study:

• To investigate C646, a p300 inhibitor, as a strategy to mitigate chemotherapy-induced toxicity.
• To determine if C646 can selectively protect noncancerous cells from p53-dependent apoptosis during chemotherapy.

Main Methods:

• Utilized C646, a reversible p300 inhibitor, to modulate p53 activity.
• Examined the effect of C646 on p53 acetylation and transcription.
• Assessed the therapeutic index of doxorubicin combined with C646 in preclinical models with differential p53 genetic backgrounds.
• Evaluated C646's protective effects against doxorubicin-induced myelosuppression (neutropenia and anemia) in mice with p53-mutant tumors.

Main Results:

• C646 treatment downregulated p53 transcription and inhibited p53 acetylation at key regulatory sites.
• Combination therapy with doxorubicin and C646 improved the therapeutic index by selectively protecting hematopoietic cells.
• In mice with p53-mutant tumors, C646 administration significantly reduced doxorubicin-induced neutropenia and anemia without compromising antitumor efficacy.

Conclusions:

• Temporary and reversible inhibition of p53 acetylation using C646 offers a promising strategy to reduce severe chemotoxicity.
• This approach is particularly beneficial for cancer patients with p53-mutant tumors, allowing for continued and effective chemotherapy treatment.