Functional Passenger-Strand miRNAs in Exosomes Derived from Human Colon Cancer Cells and Their Heterogeneous...

Area of Science:

• Oncology
• Molecular Biology
• Cell Biology

Background:

• Exosomes are crucial in cancer progression, mediating intercellular communication via microRNAs (miRNAs).
• Passenger-strand miRNAs (miRNA*s), often overlooked, are present in miRNA processing.
• The functional roles of miRNA*s within cancer-derived exosomes remain largely unexplored.

Purpose of the Study:

• To identify functional passenger-strand miRNAs (miRNA*s) in exosomes from human colon cancer cells (SW620).
• To investigate the distinct roles of passenger-strand miRNAs in colon cancer progression.
• To explore the role of exosomal integrin β4 in colon cancer cell uptake and paracrine signaling.

Main Methods:

• High-throughput sequencing to compare miRNA profiles in SW620 colon cancer cells and NCM460 normal colonic epithelial cells.
• Categorization of differentially expressed miRNAs into "high in exosome and high in cell" (HEHC) and "high in exosome but low in cell" (HELC) sets.
• Functional assays using exosome transfection and integrin β4 manipulation to assess cellular effects.

Main Results:

• Two passenger-strand miRNAs, miR-2277-3p (HELC) and miR-26b-3p (HEHC), exhibited opposing functions.
• miR-2277-3p promoted SW620 cell proliferation, migration, and invasion by targeting NUPR1L.
• miR-26b-3p showed inhibitory effects by targeting PFDN1, but exosomes rich in miR-26b-3p did not suppress tumors.
• Exosomes enriched with miR-2277-3p showed high integrin β4 abundance, influencing exosome uptake and paracrine effects.

Conclusions:

• Passenger-strand miRNAs are abundant in colon cancer exosomes and can be categorized into distinct functional sets.
• miR-2277-3p and miR-26b-3p demonstrate opposing roles in colon cancer, with miR-2277-3p promoting oncogenesis.
• Integrin β4 serves as a marker for exosome heterogeneity in colon cancer, regulating exosome uptake and paracrine signaling.