MiR-199a-3p Induces Mesenchymal to Epithelial Transition of Keratinocytes by Targeting RAP2B

Area of Science:

• Molecular Biology
• Oncology
• Dermatology

Background:

• Cutaneous squamous cell carcinoma (CSCC) progresses through pre-malignant stages with known microRNA (miRNA) alterations.
• Decreased miR-199a-3p expression correlates with later stages of epidermal carcinogenesis.
• Epithelial-to-mesenchymal transition (EMT) is critical for carcinoma invasion, involving loss of cell-cell contacts and increased motility.

Purpose of the Study:

• To investigate the role of diminished miR-199a-3p in keratinocyte EMT during CSCC development.
• To identify biochemical targets of miR-199a-3p involved in EMT.
• To explore mechanisms underlying miR-199a-3p downregulation in CSCC.

Main Methods:

• Quantification of miR-199a-3p levels across epidermal carcinogenesis stages.
• Photoactivatable Ribonucleoside-Enhanced Crosslinking and Immunoprecipitation (PAR-CLIP) to identify miR-199a-3p targets.
• Analysis of Ras-associated protein B2 (RAP2B) expression in CSCC biopsies and evaluation of miR-199a-3p's effect on focal adhesion kinase (FAK) phosphorylation.

Main Results:

• Ras-associated protein B2 (RAP2B) was confirmed as a direct target of miR-199a-3p.
• Overexpression of miR-199a-3p in CSCC cells induced a mesenchymal-to-epithelial transition (MET), reducing EMT markers and phosphorylated FAK.
• DNA methylation was identified as a mechanism for miR-199a-3p inhibition, independent of promoter methylation.

Conclusions:

• miR-199a-3p suppresses EMT in CSCC by targeting RAP2B, thereby inhibiting cancer cell invasion.
• The miR-199a-3p/RAP2B axis and FAK phosphorylation are critical regulators of EMT in CSCC.
• Targeting RAP2B or FAK phosphorylation presents a potential therapeutic strategy for CSCC.