Rimonabant-induced apoptosis in leukemia cell lines: activation of caspase-dependent and -independent pathways

Area of Science:

• Oncology
• Pharmacology
• Cell Biology

Background:

• Rimonabant (SR141716), a cannabinoid CB1 receptor antagonist, is recognized for its anti-obesity effects.
• Emerging research indicates SR141716 possesses antitumor properties, prompting further investigation into its mechanisms.

Purpose of the Study:

• To evaluate the antitumor potential of SR141716 in leukemia cell lines.
• To assess the toxicity of SR141716 in normal peripheral blood mononuclear cells (PBMCs).
• To elucidate the mechanisms underlying SR141716-induced cell death in leukemia cells.

Main Methods:

• Treatment of Jurkat and U937 leukemia cell lines with SR141716 (1-20 microM).
• Analysis of cell number, cell cycle progression (G0/G1 block), apoptosis (morphology, phosphatidylserine exposure, DNA fragmentation), necrosis, and mitochondrial membrane potential.
• Investigation of caspase-dependent and -independent cell death pathways, including PARP activation and PI3K/AKT signaling.

Main Results:

• SR141716 significantly reduced leukemia cell numbers by inducing apoptosis and necrosis.
• Distinct cellular responses were observed: U937 cells showed a G0/G1 cell cycle arrest, while Jurkat cells underwent apoptosis.
• SR141716 triggered mitochondrial depolarization and modulated caspase-dependent/independent pathways, including PARP activation and PI3K/AKT signaling, with cell-type specific variations.

Conclusions:

• SR141716 demonstrates significant antitumor activity against leukemia cells with low toxicity to normal PBMCs.
• The drug induces cell death through apoptosis and necrosis, involving cell cycle arrest and mitochondrial dysfunction.
• SR141716 activates alternative cell death pathways, highlighting its versatile therapeutic potential in leukemia treatment.