Paramedical Sciences and Military Health

Introduction: Epigenetic changes such as promoter methylation of tumor suppressor genes (TSGs) is one of the most important mechanisms involved in the development of hematologic malignancies. Harmine is one of the Harmal-derived alkaloids with anti-proliferatory effects on leukemia cell lines. Since P16 and DAPK genes are hypermethylated in some hematologic malignancies, the current study aimed to investigate the effect of Harmine on the expression of these two genes in HL60 Leukemia cell line to take steps towards clarifying the mechanism of it’s anti-proliferatory effect.

Methods and Materials: HL60 cells were seeded into 96 well plates containing RPMI medium supplemented with 10% FBS, 1% penicillin or streptomycin, and then incubated at 37°C in a humid environment at 5% CO2. Cell count and viability were determined after 24, 48, and 72 hours in the presence of Harmine and 5-azacytidine. Gene expression analysis was performed by quantitative real time PCR. Finally, statistical analysis was carried out using SPSS software.

Results: Based on the results, Harmine suppresses cell proliferation in all concentrations. Comparing the control group, Harmine at 25.6 µg/ml and 102.4 µg/ml concentrations reduces cell proliferation to 50 and 78 percent at 72 hours, respectively (P<0.001). The results demonstrate that Harmine at 102.4 µg/ml concentration significantly upregulates DAPK expression (P<0.005). However, its effect was not significant on p16 expression (P>0.05).

Discussin and Conclusion: The results indicate that Harmine have inhibitory effect on HL60 leukemia cell line in a dose and time-dependent manner. Furthermore, Harmine can induce DAPK upregulation that might be related to DAPK gene hypomethylation. Further comprehensive and elucidative investigations are needed for better understanding of the Harmine effect on leukemic cells.