[Study on the Mechanism of Piperlongumine Inducing Ferroptosis in K562/ADR Cells through the miR-214-3p/GPX4 Pathway]

To investigate the effect of piperlongumine(PL) on the proliferation and ferroptosis of human adriamycin-resistant chronic myeloid leukemia K562/ADR cells, and to explore its possible molecular mechanism.

CCK-8 assay was used to detect the effect of PL on the survival rate of K562/ADR cells and to screen the appropriate drug concentration. After K562/ADR cells were treated with low, medium and high concentrations of PL(2, 4, and 6 μmol/L), EdU proliferation assay and plate colony formation assay were used to detect cell proliferation and colony formation ability. CCK-8 assay was used to detect the effects of different inhibitors (Fer-1, Z-VAD, Nec-1) combined with PL on cell proliferation. The intracellular Fe²⁺, ROS, malondialdehyde(MDA) and glutathine(GSH) contents were respectively detected by iron ion colorimetry, DCFH-DA fluorescent probe, MDA and GSH kits. RT-qPCR and Western blot were respectively used to detect the expression level of GPX4 mRNA and protein in cells. Bioinformatics websites predicted miRNA that could target and regulate GPX4 . RT-qPCR was used to detect the effects of different concentrations of PL on the expression levels of the predicted miRNA. Dual luciferase gene reporter assay was used to verify the targeting relationship between miR-214-3p and GPX4 . After treating cells with PL or PL+miR-214-3p inhibitor, the Fe²⁺, ROS, MDA, GSH centents and GPX4 protein expression levels in cells were detected.

PL inhibited K562/ADR cell proliferation in a concentration-dependent manner（r =0.979）. Compared with the blank control group, the survival rate, EdU positive cells rate in low, medium and high concentration PL groups were significantly decreased (P < 0.01). Compared with the PL group alone, the survival rate of cells in the Z-VAD+PL group was increased slightly (P < 0.05). The cell survival rate was significantly increased in medium or high concentration PL+Fer-1 group (P < 0.01). Compared with blank control group, ROS expression level in low concentration PL group was slightly increased (P < 0.05), and GSH content was slightly decreased (P < 0.05). In medium and high concentration PL groups, the contents of Fe²⁺, ROS and MDA were significantly increased (P < 0.01), while the contents of GSH, expression of GPX4 mRNA and protein were significantly decreased(P < 0.01). Bioinformatics prediction and double luciferase reporter gene experiment confirmed the targeting relationship between GPX4 and miR-214-3p. Compared with the blank control group, the expression level of miR-214-3p in cells of medium and high concentration PL groups was significantly increased (P < 0.01). Compared with PL group alone, the intracellular Fe²⁺, ROS and MDA contents in PL+miR-214-3p inhibitor group were all decreased (P < 0.01), while GSH content and GPX4 protein expression levels were significantly increased (P < 0.01).

Medium and high concentrations of PL can inhibit the proliferation of K562/ADR cells by inducing ferroptosis, which is related to the regulation of miR-214-3p pathway.