Network effect of Wt-mutant p53 interactions and implications on p53 gene therapy

Area of Science:

• Molecular Biology
• Oncology
• Genetics

Background:

• Mutant p53 proteins can exert dominant-negative or gain-of-function effects, disrupting normal p53 tumor suppressor activities.
• Maintaining genomic stability is a critical function of wild-type p53, and its disruption is a hallmark of cancer.
• Hepatocellular carcinoma (HCC) frequently harbors TP53 mutations, suggesting a significant role in hepatocarcinogenesis.

Purpose of the Study:

• To investigate the impact of TP53 mutations found in HCC on the transcriptional and apoptotic activities of p53.
• To analyze the interplay between wild-type p53 and its mutants in regulating target gene expression.
• To elucidate the molecular mechanisms by which p53 mutants interfere with wild-type p53's function.

Main Methods:

• Screening of TP53 mutations in 202 Chinese HCC patient samples.
• Analysis of transcriptional and apoptotic activities of 21 p53 mutants in the presence or absence of wild-type p53.
• Development and application of a kinetic model to understand p53 WT/mutant heterotetramer function.

Main Results:

• Identification of a novel point mutation (p.P72A) and a long frameshift mutation (p.E294SfsX51).
• TP53 mutations in HCC were frequently associated with mutants lacking dominant-negative inhibition on p21 transcription.
• An inverse correlation was observed between p21 and BAX transcription activation by p53 WT/mutant heterotetramers, suggesting differential binding modes.

Conclusions:

• p53 mutants significantly interfere with wild-type p53's ability to maintain genomic stability in HCC.
• The differential regulation of p21 and BAX transcription by p53 heterotetramers is a key mechanism of mutant p53's oncogenic activity.
• Understanding these interactions provides insights into therapeutic strategies targeting p53 dysfunction in cancer.