Functional proteomics identifies miRNAs to target a p27/Myc/phospho-Rb signature in breast and ovarian cancer

Area of Science:

• Oncology
• Molecular Biology
• Genetics

Background:

• The myc oncogene is frequently overexpressed in breast and ovarian cancers, driving tumor progression.
• Targeting myc therapeutically is challenging due to its role in multiple cellular processes.
• A specific protein signature (high myc, low p27, high phospho-Rb) correlates with poor patient survival.

Purpose of the Study:

• To identify microRNAs (miRNAs) capable of reversing the identified poor prognostic protein signature.
• To investigate the therapeutic potential of identified miRNAs in preclinical cancer models.

Main Methods:

• Functional proteomics screening of a miRNA library in cancer cell lines.
• Integration of data from patient tumors to identify key miRNAs.
• Mechanistic studies on miR-124's effect on p27 expression and cell cycle.
• In vivo studies using xenograft models with nanoparticle-mediated miRNA delivery.

Main Results:

• A panel of five miRNAs (miR-124, miR-365, miR-34b*, miR-18a, miR-506) were identified as potential tumor suppressors.
• miR-124 demonstrated an RNA-activation function, directly inducing p27 protein levels and causing G1 cell cycle arrest.
• Nanoparticle-delivered miR-124 reduced tumor growth and sensitized cancer cells to etoposide in vivo.

Conclusions:

• The identified miRNAs, particularly miR-124, can reverse the p27/myc/phospho-Rb signature associated with poor prognosis.
• miR-124 exhibits therapeutic potential by directly targeting the p27 promoter and inhibiting tumor growth.
• miRNAs represent a promising therapeutic strategy for targeting the functional impact of myc in cancer.