Work

MicroRNA‑155‑5p‑dependent upregulation of PDCD4 is involved in oridonin‑induced proliferation inhibition of leukemia cells

Year: 2026

Type: article

Abstract: As the antitumor mechanism of oridonin has not been clearly demonstrated, the effect of programmed cell death protein 4 (PDCD4) regulated by microRNA (miR)-155-5p on the proliferation of leukemia cells after exposure to oridonin was detected.The CCK-8 assay indicated that proliferation of the three kinds of leukemia cells was inhibited by oridonin, with the most significant inhibitory rate on HL60 cells compared with NB4 and U937 cells.Regarding the cell cycle profile, there was downregulation of the S phase, upregulation of the G 2 /M phase and no significant change in the G 0 /G 1 phase.The downregulation of miR-155-5p was demonstrated by the differentially gene chromatin immunoprecipitation and verified using RT-qPCR in HL60 cells treated with oridonin.Compared with the oridonin group, the expression of miR-155-5p was restored after co-transfection of miRNA-155-5p mimics with oridonin, and the miR-55-5p inhibitor significantly downregulated the expression of miR-155-5p compared with the control group.The proliferation of HL60 cells was restored after simultaneous transfection of miR-55-5p mimics and treatment with oridonin and the miR-155-5p inhibitor could significantly downregulate proliferation of HL60 cells.After intersection analysis based on StarBase and miRDB, PDCD4 was identified to be a possible downstream apoptosis-related target gene.After exposure to oridonin, the expression of PDCD4 of HL60 cells was significantly upregulated and it was significantly decreased after simultaneous transfection of miR-155-5p mimics plus treatment with oridonin compared with the mimics control group and the proliferation level was restored.The targeted regulation of miR-155-5p on PDCD4 was demonstrated using a luciferase assay and miR-155-5p was negatively associated with PDCD4.The expression of PDCD4 was significantly downregulated after treatment with si-PDCD4 transfection together with oridonin compared with oridonin, which was accompanied by proliferation restoration of HL60 cells.Furthermore, apoptosis of HL60 cells was induced by oridonin, which was associated with the decrease of miR-155-5p and increase of PDCD4 that was verified using miR-155-5p mimics and si-PDCD4 transfection, respectively.The upregulation of the Bax/Bcl-2 ratio resulted in upregulation of cleaved caspase-3 and -9 expression, which was identified using a si-PDCD4 transfection assay.In conclusion, The miR-155-5p dependent upregulation of PDCD4 expression resulted in the increase of Bax/Bcl-2 ratio and activation of caspase-3 and -9, which contributed to the apoptosis of HL60 cells induced by oridonin.

Source: Oncology Letters

DOI: 10.3892/ol.2026.15919