Propolis inhibits the proliferation of human leukaemia HL-60 cells by inducing apoptosis through the mitochondrial pathway

Abstract

Propolis, a natural product derived from plant resins collected by honeybees, has been reported to exert a wide spectrum of biological functions. This research aimed at investigating the effect of propolis on the proliferation of human leukaemia HL-60 cells and whether propolis might induce apoptosis in HL-60 cells. The results showed dose- and time-dependent decreases in the proliferation of HL-60 cells treated with propolis (above 3 µg mL⁻¹ of propolis). Further studies revealed that the anti-proliferative effects of propolis were caused by inducing apoptosis. Agarose electrophoresis of genomic DNA of HL-60 cells treated with propolis showed the ladder pattern typical for apoptotic cells. Propolis induced the activation of caspase-3 and cleavage of poly (ADP-ribose) polymerase in HL-60 cells. Propolis also induced the release of cytochrome c from mitochondria to cytosol. Taken together, these findings demonstrate that the inhibitory effect of propolis on HL-60 cell proliferation is caused by inducing apoptosis through the mitochondrial pathway.

Keywords:

• apoptosis
• caspase-3
• cytochrome c
• HL-60
• PARP
• propolis

Acknowledgements

This work was supported by 2006 Kyonggi University Specialization Program. We are grateful to Dong-Soo Kim for supplying the propolis.