Tier 3 — preclinical

Fisetin, an Anti-Inflammatory Agent, Overcomes Radioresistance by Activating the PERK-ATF4-CHOP Axis in Liver Cancer

Kim TW
International Journal of Molecular Sciences 2023 Volume 24, issue 10, article 9076

Bibliography

PubMed
PMID 37240422
PubMed Central
PMC10218992
DOI
10.3390/ijms24109076
Funding
Basic Science Research Program through the National Research Foundation of Korea (NRF), funded by the Ministry of Education (2018R1D1A1B07048556), and the Dongguk University Research Fund of 2022.
Competing interests
The author declares no conflict of interest.

Study snapshot

DesignIn vitro cell viability, LDH, caspase-3, siRNA knockdown and western blot studies in liver cancer cell lines and radio-resistant sublines, plus an in vivo HepG2 xenograft nude mouse model.
ModelHuman liver cancer cell lines HepG2, Hep3B and Huh-7 and radio-resistant HepG2R/Hep3BR sublines; macrophage cell line Raw264.7; athymic BALB/c nude mice bearing HepG2 xenografts (n=10/group).
SampleCell assays performed in triplicate; xenograft mice n=10 per group (PBS, fisetin 50 mg/kg, fisetin 100 mg/kg).
InterventionFisetin 10-200 micromolar in vitro; fisetin 50 or 100 mg/kg administered intraperitoneally every other day in vivo; radiation exposure of 2, 4 or 6 Gy in radioresistance experiments.
DurationIn vitro treatments up to 24 hours; in vivo tumour monitoring over 35 days.
EndpointsPro-inflammatory cytokine expression (TNF-alpha, IL-1beta, IL-6) in LPS-stimulated macrophages; Cell viability, LDH and caspase-3 activity in liver cancer cells; Intracellular calcium release and ER stress markers (CHOP, PERK, p-eIF2alpha, ATF4, GRP78); Exosomal GRP78 secretion; Xenograft tumour volume and body weight; Colony formation and EMT markers (E-cadherin, N-cadherin, vimentin) after radiation

What the study showed, in plain terms

This Korean study looked at two things: whether fisetin calms inflammatory signalling in immune cells, and whether it can help kill liver cancer cells - including cancer cells that have become resistant to radiotherapy.

Fisetin reduced inflammatory cytokine release in LPS-stimulated macrophages, and separately killed liver cancer cells (HepG2, Hep3B, Huh-7) in a dose-dependent way by triggering a stress response inside the cell's protein-folding machinery (the endoplasmic reticulum), releasing calcium and activating a pathway called PERK-ATF4-CHOP that leads to programmed cell death.

In mice carrying human liver tumours, fisetin injections slowed tumour growth. Most notably, in liver cancer cells that had been made resistant to radiation in the lab, fisetin combined with radiation reactivated this same stress-death pathway and reversed a cancer-spreading process called epithelial-mesenchymal transition, effectively overcoming the radioresistance.

This is laboratory and animal mechanism work using injected fisetin at cancer-research doses, not a test of oral fisetin supplements, so it speaks to a possible future radiotherapy-sensitising role for fisetin rather than to current supplement use.

Key findings

  • Fisetin reduced LPS-induced TNF-alpha, IL-1beta and IL-6 in macrophages
  • Fisetin induced dose- and time-dependent apoptosis in HepG2, Hep3B and Huh-7 liver cancer cells
  • Fisetin triggered ER stress via intracellular calcium release and the PERK-ATF4-CHOP pathway
  • GRP78 knockdown or PERK/CHOP silencing blocked fisetin-induced cell death
  • Fisetin reduced tumour volume in a HepG2 xenograft mouse model
  • Fisetin combined with radiation overcame radioresistance by suppressing EMT in HepG2R/Hep3BR cells

What this study can and cannot tell us

Single-author, single-institution study; clinical trials in liver cancer patients could not be performed and were not attempted.

Radio-resistant cell lines were generated in vitro over three months of repeated radiation exposure and may not fully recapitulate clinical radioresistance mechanisms in patients.

Editorial review

Reviewed by the Biohack Blueprint research team

Last verified

Dr. Khaled Mahmoud, MBBChCritical Care Medicine, Longevity Science & Editorial Direction Dr. Amr Yasser, PhDCardiometabolic, Musculoskeletal, Gut & Bioavailability Dr. Abdulla Mostafa, PhDCellular Senescence, Neurological, Mitochondrial & Brain-Ageing Biology