Inhibition of telomerase activity and cell growth by free and nanoliposomal forms of punicalagin in human leukemia cell line K562

Purpose: To prepare punicalagin-loaded nanoliposome and compare its anti-telomerase activity in K562 cell line with that of free punicalagin.
Methods: Punicalagin-loaded nanoliposomes were prepared by extrusion method, and the efficiency of punicalagin entrapment was determined by high-performance liquid chromatography (HPLC) method. The anti-proliferation effect of the punicalagin in the free and nanoliposomal forms at various doses (0 - 100 μg/mL) and times (0 - 72 h) on K562 cell line was investigated using 3-(4,5-dimethylthiazol-2-yl)- 2,5-diphenyl tetrazolium bromide ((MTT) assay. Changes in telomerase activity, following treatment with punicalagin, of the free and nanoliposomal forms were measured by telomeric repeat amplification protocol-enzyme-linked immunosorbent assay.
Results: The entrapment efficiency of punicalagin was 86.7 ± 1 %. Treatment of K562 cells with punicalagin, particularly in the nanoliposomal form, resulted in significant induction of apoptosis and inhibition of cell growth. Furthermore, the telomerase activity of the nanoliposomal punicalagin-treated cells was significantly inhibited in a time- and dose-dependent manner.
Conclusion: Punicalagin shows a novel mechanism of anti-telomerase activity, particularly in the nanoliposomal form, and may provide a basis for the future development of anti-cancer therapy.

Keywords
Punicalagin; Apoptosis; Anti-proliferative; Nanoliposome; Telomerase; Leukemia