Huashi Jiedu Decoction Enhances 5-Fluorouracil Efficacy in Gastric Cancer via miRNA-21-3p/p53 Pathway.

[PURPOSE] To explore the mechanism of Huashi Jiedu Decoction (HJD) synergizing with 5-fluorouracil (5-Fu) in gastric cancer (GC) therapy.

[METHODS] MicroRNAs (miRNAs) and genes involved in HJD-mediated GC treatment were identified using ultra-high-performance liquid chromatography coupled with quadrupole-Orbitrap mass spectrometry, network pharmacology, Gene Ontology, Kyoto Encyclopedia of Genes and Genomes, and molecular docking. The effects of HJD on 5-Fu sensitivity in BGC-823 cells were evaluated with 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assays, reverse transcription quantitative polymerase chain reaction (RT-qPCR), and Western blotting. Synergistic effects in vector-transfected and miRNA-21-3p knockdown cells were assessed by colony formation, wound healing, transwell assays, and flow cytometry (FCM). An in vivo study evaluated the impact of HJD on 5-Fu sensitivity, measuring miRNA-21-3p, tumor protein p53 (p53), N-cadherin, vimentin, and E-cadherin in tumors, along with tumor volume and weight.

[RESULTS] miRNA-21-3p and p53 were key targets in HJD's therapeutic effect on GC. RT-qPCR showed that HJD combined with 5-Fu reduced miRNA-21-3p and upregulated p53 in vector cells and increased p53 mRNA ( < 0.01) and protein ( < 0.05) compared to 5-Fu alone. These effects were abolished in miRNA-21-3p knockdown cells. The combination reduced colony formation by 48.92% ( < 0.01), suppressed transwell migration by 28.5% ( < 0.01), and inhibited wound healing by 81.9% compared to 5-Fu monotherapy ( < 0.001), with no effects in knockdown cells. FCM showed a 15.1% increase in G/G phase arrest ( < 0.05). In vivo, the combination significantly reduced tumor volume ( < 0.05) and weight by 18.7%, with concomitant miRNA-21-3p downregulation ( < 0.0001), EMT marker suppression (N-cadherin, vimentin), and tumor suppressor activation (p53, E-cadherin) versus 5-Fu alone.

[CONCLUSION] HJD enhances 5-Fu's effects on GC by regulating the miRNA-21-3p/p53 pathway and modulating cadherin expression, supporting its potential as an adjunctive treatment in GC.