In vitro antiglioma action of indomethacin is mediated via AMP-activated protein kinase/mTOR complex 1 signalling...

Area of Science:

• Biochemistry
• Molecular Biology
• Oncology

Background:

• The AMP-activated protein kinase (AMPK) and mammalian target of rapamycin (mTOR) pathway regulates cellular energy homeostasis.
• Dysregulation of the AMPK/mTOR pathway is implicated in various cancers, including glioma.
• Cyclooxygenase (COX) inhibitors are being explored for their potential anticancer properties.

Purpose of the Study:

• To investigate the role of the AMPK/mTOR pathway in the antiglioma effects of the COX inhibitor indomethacin.
• To compare the efficacy of indomethacin with other COX inhibitors against glioma cells.
• To elucidate the molecular mechanisms underlying indomethacin-induced glioma cell death.

Main Methods:

• In vitro studies using U251 human glioma cells and primary human glioma cells.
• Treatment with indomethacin and other COX inhibitors (diclofenac, naproxen, ketoprofen).
• Assessment of cell viability, cell cycle progression, apoptosis, oxidative stress, and mitochondrial function.
• Analysis of AMPK and mTOR pathway activation through Western blotting and RNA interference.
• Measurement of intracellular ATP and AMP/ATP ratios.

Main Results:

• Indomethacin demonstrated superior potency in reducing glioma cell viability compared to other tested COX inhibitors.
• Indomethacin induced G2M cell cycle arrest, oxidative stress, mitochondrial depolarization, caspase activation, and apoptosis.
• Indomethacin activated AMPK signaling (increased phosphorylation of AMPK, Raptor, ACC) and inhibited mTORC1 signaling (decreased phosphorylation of mTOR, p70S6K, PRAS40).
• AMPK activation by indomethacin was linked to intracellular ATP depletion and increased AMP/ATP ratio.
• AMPK knockdown or mTORC1 activation abrogated indomethacin's cytotoxic effects, while AMPK activators mimicked them.
• Similar AMPK/mTORC1 pathway modulation was observed in primary human glioma cells.

Conclusions:

• The study demonstrates that indomethacin exerts its antiglioma effects through the activation of the AMPK pathway and subsequent inhibition of mTORC1.
• The findings highlight the critical role of the AMPK/mTOR pathway in mediating indomethacin's cytotoxicity against glioma cells.
• Indomethacin's potential as a therapeutic agent for glioma warrants further investigation, particularly concerning its impact on the AMPK/mTOR pathway.