Targeting PIP5K ameliorates hepatic cancer by inhibiting PI3K/AKT and the autophagy mechanism and enhancing...

Hepatic cancer cells regulate reactive oxygen species (ROS) and lipid kinases to promote proliferation and survival. The role of phosphatidylinositol-4-phosphate-5-kinase (PIP5K) in modulating the autophagy-Nrf2 antioxidant pathway remains unclear. In this study, we investigated the impact of PIP5K on the ROS-dependent autophagy-Nrf2 axis using specific isoform inhibitors (PIP5K1A: ISA-201IB; PIP5K1B: IITZ01) and further identified NG-TZ-17 and NG-TZ-20, which are analogs of IITZ01, as novel inhibitors of the PIP5KB isoform.

The association between PIP5K and the ROS-autophagy-Nrf2 pathway was examined in hepatocellular carcinoma (HCC) tissue samples (n = 36) and hepatic cancer cell lines. In vitro, HepG2 cells (expressing high PIP5K levels) were treated with PIP5K isoform-specific inhibitors, autophagy inhibitors, and Nrf2 inhibitors in the presence of hydrogen peroxide (H₂O₂). The effects on ROS generation, proliferation, autophagy, antioxidant defense, and apoptosis were assessed using MitoSOX staining, immunofluorescence, and Western blot analysis. In vivo, SCID mice xenografted with GFP-HepG2 cells were treated orally with PIP5K inhibitors (IITZ01 and NG-TZ-17; 50 mg/kg) or sorafenib (60 mg/kg). Tumor progression was monitored through animal imaging, survival analysis, tumor volume measurement, and Western blotting of excised tumors.

PIP5K isoforms, Beclin-1, and Nrf2 expression increased with advancing HCC grade. Autophagy induction upregulated PIP5K isoforms, Nrf2, HO-1, and SOD2, thereby protecting cells from hydrogen peroxide-induced apoptosis. PIP5K inhibition enhanced ROS-mediated apoptosis by suppressing proliferation, autophagy, and Nrf2 signaling. In vivo, NG-TZ-17 and IITZ01 significantly reduced tumor burden, with efficacy comparable to sorafenib (p < 0.001 vs. vehicle control).

PIP5K isoforms promote hepatic cancer cell proliferation under oxidative stress conditions. Targeting PIP5K sensitizes cells to ROS-mediated apoptosis through modulation of the PI3K/AKT/mTOR and autophagy pathways, highlighting PIP5K as a promising therapeutic target in hepatocellular carcinoma.