Late-Stage Downregulation of miR-138-5p Promotes Colorectal Cancer Progression

Area of Science:

• Molecular Biology
• Oncology
• Genetics

Background:

• Colorectal cancer (CRC) presents a significant global health challenge with incompletely understood molecular drivers.
• MicroRNAs (miRNAs) are implicated in CRC, but their stage-specific roles and mechanisms require further investigation.
• miR-138-5p is notably downregulated in CRC, suggesting a potential tumor-suppressive function.

Purpose of the Study:

• To investigate the stage-specific expression of miR-138-5p during colorectal cancer progression.
• To elucidate the molecular mechanisms underlying miR-138-5p's function in CRC.
• To validate miR-138-5p as a potential therapeutic target in colorectal cancer.

Main Methods:

• Differential expression profiling of healthy colon, adenomatous polyp, and CRC tissues using public datasets.
• Functional assays (clonogenic survival, proliferation, migration, cell death, 3D culture) in CRC cell lines with forced miR-138-5p expression.
• Transcriptomic profiling and integrated computational/experimental analyses to identify miR-138-5p targets.

Main Results:

• miR-138-5p is significantly downregulated in CRC but not in adenomatous polyps, indicating a role in later malignant progression.
• Overexpression of miR-138-5p suppressed CRC cell proliferation, survival, migration, and tumor formation in vitro.
• Transcriptomic analysis revealed miR-138-5p regulates pathways including zinc ion binding and smoothened signaling, with TCF3, UBE2C, EIF4EBP1, LYPLA1, and CD44 validated as targets.

Conclusions:

• miR-138-5p functions as a stage-specific tumor suppressor in colorectal cancer, with its downregulation being a late oncogenic event.
• miR-138-5p exerts its effects by coordinating oncogenic networks.
• Restoration of miR-138-5p or targeting its downstream effectors presents a promising therapeutic strategy for CRC.