Aqueous urtica dioica leaves extract inhibits proliferation of acute myeloid leukemia cells in vitro

Abstract

Introduction: AML, considered as the most common type of leukemia, is characterized by the dysregulation between alive and Abstracts Clinical Lymphoma, Myeloma & Leukemia September 2017 - S279 dead cells, due to either alteration in tumor suppressor genes or activation of oncogenes, resulting in the accumulation of immature cells in the bone marrow. Urtica dioica (UD) is known to have various pharmacological activities as anti-bacterial, anti-inflammatory and anti-cancerous. The aim of this study is to examine the effect of aqueous leaves extract on the proliferation of U937 cell line. Materials and Methods: UD leaves were washed and placed in boiling water for 30 minutes. The aqueous extract was filtered, centrifuged., and the supernatant was stored at -20C. AML U937 cells were plated and treated with various concentrations of UD extract for 48/72 hours. Cell proliferation was assessed using WST1 reagent. Cell Cycle Analysis was performed by propidium iodide staining and assessing DNA content by flow cytometry. Apoptosis was investigated by staining with Annexin V/PI followed by flow cytometry. Proteins involved in apoptosis were Quantified by western blots. Results: The results showed a decrease in the proliferation of U937 after 48hrs with IC50 at 24mg/ml. The decrease was more significant after 72hr with an IC50 at 16mg/ml. Thus, UD extract exerts an anti-proliferative effect in a dose- and timedependent manner. Furthermore, assessment of DNA content of cells using flow cytometry revealed an accumulation of cells in the pre-G0 phase. To confirm apoptosis, AnnexinV/PI dual staining method was performed showing a time- and dose-dependent increase in the number of cells in the early and late apoptosis stage. With respect to the proteins studied, treatment with Urtica dioica extract significantly increased the expression of the pro-apoptotic protein Bax with concomitant decrease in the anti-apoptotic protein Bcl-2 expression. Moreover, the expression of procaspase-3 also decreased indicating its activation by cleavage, which proves the ability of UD in promoting a caspase-dependent apoptotic pathway. Conclusion: Results obtained prove the pro-apoptotic effect of UD aqueous leaf extract on acute myeloid leukemia cells in vitro in a dose- and timedependent manner. Further investigations are needed to identify the active compound(s) in UD.