5-Fluorouracil treatment represses pseudouridine-containing miRNA export into extracellular vesicles

Area of Science:

• Molecular Biology
• Cancer Research
• Biochemistry

Background:

• 5-Fluorouracil (5-FU) is a long-standing chemotherapy agent primarily known for inhibiting DNA synthesis.
• Emerging evidence suggests 5-FU also affects RNA metabolism, including modifications and ribosome function.
• Small extracellular vesicles (sEVs) mediate cell-cell communication through their cargo of proteins and RNAs.

Purpose of the Study:

• To investigate the impact of 5-FU on post-transcriptional small RNA modifications (PTxMs).
• To analyze the effect of 5-FU on the expression and export of RNA within sEVs.
• To understand how 5-FU influences RNA content and modifications in both cancer cells and secreted sEVs.

Main Methods:

• Colorectal cancer (CRC) cells were treated with 5-FU.
• Small RNA sequencing was performed on cellular and sEV fractions.
• Analysis of RNA modifications, including pseudouridine and methylation, was conducted.

Main Results:

• 5-FU treatment altered the export of specific small RNAs into sEVs, repressing miRNA and snRNA-derived RNAs while promoting snoRNA-derived RNAs.
• A significant decrease in pseudouridine modification was observed in both cellular and sEV small RNAs after 5-FU exposure.
• Conversely, 5-FU treatment led to an increase in methylated bases in cellular small RNAs.

Conclusions:

• 5-FU exposure significantly disrupts RNA expression, base modification profiles, and the trafficking of small RNAs.
• These findings reveal novel mechanisms by which 5-FU affects cancer cells beyond DNA synthesis inhibition.
• The study highlights the role of 5-FU in altering RNA-based intercellular communication via sEVs.