Negative regulation-resistant p53 variant enhances oncolytic adenoviral gene therapy

Area of Science:

• Molecular Biology
• Oncology
• Gene Therapy

Background:

• Intact p53 function is crucial for cancer therapy response.
• p53 activity is often inhibited by Mdm2, adenovirus E1B 55kD protein, and its own C-terminal domain.
• Developing strategies to overcome these inhibitory mechanisms is vital for effective p53-based cancer treatments.

Purpose of the Study:

• To engineer a p53 variant (p53VPΔ30) resistant to negative regulation by Mdm2, E1B 55kD, and the p53 C-terminal domain.
• To evaluate the efficacy of an oncolytic adenovirus vector (Ad-mΔ19/p53VPΔ30) carrying the engineered p53 variant in cancer cell lines and preclinical models.

Main Methods:

• Generation of p53VPΔ30 by deleting N- and C-terminal regions of wild-type p53 and inserting the VP16 transcriptional activation domain.
• Construction of an oncolytic adenovirus vector, Ad-mΔ19, expressing p53VPΔ30.
• Assessment of cytotoxicity and apoptosis induction in human cancer cell lines.
• Evaluation of antitumor effects and survival rates in mouse xenograft models.

Main Results:

• Ad-mΔ19/p53VPΔ30 demonstrated superior cytotoxicity compared to vectors with wild-type p53 or other variants.
• p53VPΔ30 accumulated and induced apoptosis independently of endogenous p53 and Mdm2 levels.
• Significant antitumor activity and increased survival were observed in mice bearing U343 brain cancer xenografts.
• The engineered p53 variant retained trans-activation activity while resisting degradation.

Conclusions:

• Ad-mΔ19/p53VPΔ30 is a promising tool for p53-mediated cancer gene therapy.
• This modified p53 variant overcomes common resistance mechanisms, offering enhanced therapeutic potential.
• The study presents a novel p53 variant resistant to multiple inhibitory factors, paving the way for improved cancer treatments.