Hsa-miR-526b-5p Regulates the Sensitivity of Colorectal Cancer to 5-Fluorouracil by Targeting TP53 in Organoid Models.

This study aimed to explore the mechanisms through which microRNAs (miRNAs) regulate 5-fluorouracil (5-FU) sensitivity in colorectal cancer (CRC) using organoid models. Fresh tissue samples from CRC tumors were collected, and CRC organoids were isolated and cultured. The consistency between CRC organoids and their derived tissues was validated. CRC organoids were treated with 5-FU, and ATP activity was measured. High-throughput sequencing of CRC organoids, combined with Gene Expression Omnibus (GEO) data analysis, was performed to examine miRNA expression following 5-FU treatment. Next, we investigated the cellular function of miR-526b-5p in CRC organoids and cells. Dual-luciferase reporter assays validated the binding of miR-526b-5p to the 3' UTR of TP53 mRNA. We successfully established CRC organoids that exhibited characteristics consistent with their source tissues. 5-FU treatment suppressed the proliferation and ATP activity of CRC organoids. High-throughput sequencing of CRC organoids, combined with GEO data analysis and quantitative reverse transcription polymerase chain reaction (qRT-PCR) validation, revealed that hsa-miR-526b-5p levels were elevated following 5-FU treatment in CRC organoids and cells. Furthermore, hsa-miR-526b-5p was upregulated in CRC tissues compared to adjacent normal tissues, correlating with poor survival in CRC patients. Overexpression of hsa-miR-526b-5p mitigated the inhibitory effects of 5-FU on CRC organoid proliferation, migration, invasion, and ferroptosis. In contrast, silencing of hsa-miR-526b-5p impaired cell function and ferroptosis. Additionally, overexpression of hsa-miR-526b-5p decreased TP53 mRNA and protein levels while increasing the expression of SLC7A11 mRNA and protein. Silencing of hsa-miR-526b-5p resulted in the opposite effect. hsa-miR-526b-5p directly targeted and inhibited TP53 expression. Overexpression of TP53 diminished the promotive effect of hsa-miR-526b-5p on ferroptosis-related proteins GPX4 and SLC7A11, whereas inhibition of TP53 reversed the impact of hsa-miR-526b-5p silencing. Our study demonstrates that hsa-miR-526b-5p targets TP53 to regulate 5-FU sensitivity in CRC through the ferroptosis pathway based on CRC organoid models.