Chloroquine is a zinc ionophore

Area of Science:

• Pharmacology
• Oncology
• Cell Biology

Background:

• Chloroquine, an antimalarial drug, shows promise in cancer therapy by sensitizing cells to treatments and inducing apoptosis.
• The precise mechanisms underlying chloroquine's anticancer effects are still under investigation.

Purpose of the Study:

• To investigate the interaction between zinc ions and chloroquine in human ovarian cancer cells (A2780).
• To determine if chloroquine influences zinc uptake and its subsequent effect on cancer cell cytotoxicity.

Main Methods:

• Utilized a fluorescent zinc probe to assay zinc uptake in A2780 cells treated with chloroquine.
• Employed TPEN, a metal-binding compound, to confirm the specificity of chloroquine-induced zinc uptake.
• Used fluorescent microscopy to visualize intracellular zinc distribution, particularly in lysosomes.

Main Results:

• Chloroquine significantly enhanced zinc uptake in A2780 cells in a concentration-dependent manner.
• TPEN attenuated chloroquine-induced zinc uptake, confirming specificity.
• Copper and iron ions did not affect chloroquine-mediated zinc uptake.
• Intracellular zinc accumulated in lysosomes following chloroquine treatment, consistent with lysosomal inhibition.
• The combination of chloroquine and zinc increased chloroquine's cytotoxicity and induced apoptosis in ovarian cancer cells.

Conclusions:

• Chloroquine acts as a zinc ionophore, facilitating increased intracellular zinc concentration.
• This ionophore activity is a potential mechanism contributing to chloroquine's observed anticancer properties.
• The findings suggest a synergistic effect between chloroquine and zinc in targeting ovarian cancer cells.