Loperamide, an antidiarrhea drug, has antitumor activity by inducing cell apoptosis

Area of Science:

• Pharmacology
• Cancer Biology
• Cellular Biology

Background:

• Loperamide is a peripheral opiate agonist primarily used as an antidiarrhea drug.
• Certain opiate agonists have demonstrated the ability to induce programmed cell death (apoptosis).
• The potential anticancer effects of loperamide have not been previously investigated.

Purpose of the Study:

• To investigate the apoptosis-inducing and cytotoxic activities of loperamide.
• To evaluate loperamide's efficacy against various human tumor cell lines.
• To elucidate the mechanisms underlying loperamide's potential antitumor effects.

Main Methods:

• Cytotoxicity was assessed using the MTT assay across nine human tumor cell lines.
• Apoptosis was detected via flow cytometry, including annexin V-FITC/PI staining for early apoptosis.
• Cell cycle analysis and hypodiploid cell detection were performed using propidium iodide (PI) staining; caspase-3 activation was also analyzed.

Main Results:

• Loperamide inhibited the proliferation of all tested tumor cell lines, with notable efficacy against human osteosarcoma U2OS cells (IC₅₀ = 11.8±2.8 μM).
• Loperamide treatment induced cell apoptosis and G2/M-phase cell cycle arrest.
• Apoptotic effects, primarily early apoptosis, were observed after 6 hours of treatment, involving caspase-3 activation.

Conclusions:

• Loperamide exhibits significant cytotoxic and apoptosis-inducing activities against human tumor cell lines.
• The drug effectively inhibits tumor cell proliferation and induces cell cycle arrest.
• Loperamide demonstrates potential as an antitumor agent, warranting further investigation.