Background: Acute promyelocytic leukemia (APL) is an acute leukemia diagnosed by translocation of chromosomes 15 and 17 [T (15,17)] and aggregation of neoplastic promyelocytes which are incapable of being converted into mature cells. Today, many tend to use medicinal herbs in studies and clinical applications for treatment of cancers. Cinnamon with scientific name "cinnamomumzelanicum" is a shrub of Laurales order, lauraceae family with cinnamomum genus. It is a medicinal shrub with anti-proliferation effect on tumor cells. This study was conducted to determine the effects of aqueous cinnamon extract on HL-60 cells as a model for APL.
Materials and methods: In this in vitro experimental study, HL-60 cell line was cultured under the influence of cinnamon extract's concentrations of 0.01, 0.1, 1, and 2 mg/ml in with intervals of 24, 48, and 72 h. Growth inhibition and toxic effects of cinnamon extract were evaluated through tetrazolium salt reduction. The effect of this herb on the cell cycle was studied by flow cytometry. The Hoechst stain was used to detect apoptotic cell nuclei.
Results: Cinnamon extract inhibited the growth of HL-60 cells as correlated with concentration and time. After 72 h of treating HL-60 cells with 0.01 mg/l cinnamon extract, the growth of cells was inhibited by 90.1%. Cinnamon extract stopped the cell cycle in G1 phase and the Hoechst staining verified the apoptotic process in those cells.
Conclusion: Considering the inhibitory property of cinnamon extract, we recommend it as a single drug or besides other medications for treating promyelocytic leukemia.
Keywords: Acute promyelocytic leukemia; HL-60 cells; apoptosis; cell cycle; cinnamon extract.