Mutant p53 promotes tumor cell malignancy by both positive and negative regulation of the transforming growth factor...

Area of Science:

• Molecular oncology
• Cell signaling
• Cancer biology

Background:

• Mutant p53 proteins gain oncogenic functions, promoting tumor development.
• Transforming growth factor-beta (TGF-β) signaling has dual roles in cancer, acting as both a tumor suppressor and promoter.
• The interplay between mutant p53 and TGF-β signaling in cancer remains incompletely understood.

Purpose of the Study:

• To elucidate the molecular mechanisms by which mutant p53 modulates TGF-β pathway functions.
• To investigate how mutant p53 reconciles the seemingly contradictory roles of TGF-β signaling in cancer.

Main Methods:

• Investigated mutant p53 binding to Smad3.
• Utilized ERK signaling pathway integration analysis.
• Performed gene expression analysis of TGF-β target genes.
• Employed gene silencing (Smad2) and pharmacological inhibition (ERK).
• Introduced phosphorylation-defective mutations in p53 (Ser-392).

Main Results:

• Mutant p53 enhances binding to the Smad3 MH2 domain, dependent on ERK signaling.
• This interaction disrupts the formation of the Smad3/Smad4 complex.
• Mutant p53 differentially regulates subsets of TGF-β target genes.
• Silencing Smad2, inhibiting ERK, or mutating p53 Ser-392 abrogates mutant p53-mediated gene regulation.

Conclusions:

• Mutant p53 integrates ERK signaling to bind Smad3, disrupting Smad complex formation and altering TGF-β target gene expression.
• This mechanism explains how mutant p53 can simultaneously antagonize tumor-suppressive and synergize pro-oncogenic functions of TGF-β.
• The findings provide insight into cancer cell malignancy driven by mutant p53 and TGF-β pathway dysregulation.