1. Department of Biochemistry, Institute of Biochemistry and Biophysics, University of Tehran, Tehran, Iran 2. Department of Biochemistry, Institute of Biochemistry and Biophysics, University of Tehran, Tehran, Iran
Abstract
Introduction
The cytosine analogue, 5-azacitidine as a dna methyltransferase inhibitor is currently considered the most advanced drug for cancer therapy resulted from epigenetic changes. bone marrow is the most important tissue that hematopoiesis process occurs in it and a nest for function, migration immune and blood cells. colony stimulating factors (csfs) are necessary for proliferation and differentiation of bone marrow stem cells to blood cells. the major toxicity of 5-azacitidine is myelosuppression but its precise mechanism of action remains unknown.
Methods
In this study the toxic effects of 5-azacitidine on non-adherent bone marrow cells, a rich source of hematopoietic stem cells in the presence and absence of csfs was investigated using trypan blue exclusion, mtt assay and ethidium bromide/acridine orange staining technique.
Results
The results obtained from trypan blue and mtt assays, showed that 5-azacitidine in the absence of csfs decreased the cell survival of non-adherent bone marrow cells in a dose and time dependent manner, with ic50 value of 1 µm for 12h. inversely, the apoptotic property of 5-azacitidine was significantly decreased in the presence of csfs possessed an 8-fold greater ic50 with respect to the absence of csfs. ethidium bromide/acridine orange staining of the cells treated with 5-azacitidine revealed remarkable morphological changes such as chromatin condensation and nuclear fragmentation implying occurrence of apoptosis/necrosis.
Conclusion
In conclusion, 5-azacitidine exhibits toxic effect on bone marrow stem cells but in the presence of csfs its cytotoxicity is decreased, suggesting its usage in combination therapy for cancers.
