Global identification of miR-373-regulated genes in breast cancer by quantitative proteomics

Area of Science:

• Molecular Biology
• Cancer Research
• Proteomics

Background:

• MicroRNAs (miRNAs) are implicated in cancer, but their target genes and mechanisms are poorly understood.
• miR-373 promotes breast cancer invasion and metastasis, yet few direct targets have been confirmed.
• Existing methods primarily focus on mRNA expression, limiting comprehensive target identification.

Purpose of the Study:

• To globally identify protein-coding genes regulated by miR-373 using quantitative proteomics.
• To elucidate the mechanism by which miR-373 influences protein expression in breast cancer.
• To validate direct targets of miR-373 involved in cancer progression.

Main Methods:

• Stable Isotope Labeling by Amino acids in Cell culture (SILAC)-based quantitative proteomics.
• Bioinformatic prediction of miRNA seed sequences in 3'-untranslated regions (3'-UTRs).
• Luciferase reporter assays and mutation analysis to confirm direct miRNA-target interactions.

Main Results:

• 3666 proteins were identified, with 335 found to be regulated by miR-373.
• Downregulation of 192 proteins by miR-373, with 27 predicted targets.
• TXNIP and RABEP1 validated as direct targets, regulated via translational inhibition.
• Over 30 proteins linked to cancer invasion and metastasis identified as miR-373 targets.

Conclusions:

• miR-373 regulates protein expression primarily through translational inhibition, not mRNA degradation.
• TXNIP and RABEP1 are direct targets of miR-373.
• This study reveals novel miR-373 targets involved in breast cancer invasion and metastasis, advancing understanding of miRNA regulatory networks in cancer.