Induced prodrug activation by conditional protein degradation

Area of Science:

• Biochemistry
• Molecular Biology
• Cancer Therapy

Background:

• Enzyme prodrug therapies offer targeted cancer treatment but face safety concerns due to off-target effects.
• Conditional degradation tags can mitigate these risks by enabling therapy abortion in healthy cells.

Purpose of the Study:

• To introduce and validate Degradation-Directed Enzyme Prodrug Therapy (DDEPT) as a novel safety mechanism.
• To demonstrate the efficacy of traceless shielding (TShld) as a conditional degradation system within DDEPT.

Main Methods:

• Utilized traceless shielding (TShld) to control protein degradation, requiring rapamycin for stabilization.
• Engineered yeast cytosine deaminase as a prodrug-converting enzyme within the DDEPT framework.
• Assessed cell viability under various conditions, including the presence of 5-fluorocytosine (5-FC) and rapamycin.

Main Results:

• TShld rapidly yielded native protein products within 1 hour of rapamycin addition.
• Cell viability was compromised exclusively when both 5-FC and rapamycin were present, indicating conditional enzyme activity.
• Demonstrated successful rescue of yeast cytosine deaminase activity through rapamycin-mediated stabilization.

Conclusions:

• DDEPT, utilizing TShld, provides a robust failsafe mechanism for enzyme prodrug therapies.
• This approach significantly enhances therapeutic safety by controlling enzyme activity and minimizing off-target toxicity.
• The DDEPT system is adaptable and can be integrated with other targeting strategies for improved cancer treatment safety.