Mutant p53-R273H gains new function in sustained activation of EGFR signaling via suppressing miR-27a expression

Area of Science:

• Oncology
• Molecular Biology
• Genetics

Background:

• p53 is a critical tumor suppressor, frequently inactivated in human cancers.
• Mutant p53 not only loses its suppressive function but also gains oncogenic activities.
• The role of microRNAs (miRNAs) in mutant p53 gain-of-function is largely unexplored.

Purpose of the Study:

• To investigate the involvement of miRNAs in mutant p53 gain-of-function.
• To identify novel downstream targets of mutant p53.
• To elucidate the molecular mechanisms by which mutant p53 promotes tumorigenesis.

Main Methods:

• Reporter assays to confirm mutant p53 binding to the miR-27a promoter.
• Quantitative PCR to measure miR-27a and EGFR expression.
• Western blotting to assess extracellular signal-regulated kinase 1/2 (ERK1/2) activation.
• Cell proliferation assays and tumor xenograft models.

Main Results:

• Mutant p53-273H directly suppresses the expression of miR-27a by binding to its promoter.
• Epidermal growth factor receptor (EGFR) is identified as a direct target of miR-27a.
• The mutant p53-273H/miR-27a/EGFR axis promotes sustained EGF-induced ERK1/2 activation.
• This pathway enhances cell proliferation and contributes to tumorigenesis.

Conclusions:

• This study establishes a direct link between mutant p53 gain-of-function and miRNA regulation.
• A novel oncogenic pathway, mutant p53-273H/miR-27a/EGFR, is identified.
• This pathway plays a significant role in promoting tumor development and represents a potential therapeutic target.