ABSTRACT
Leukemia is a malignant disorder of the blood progenitor/stem cells which is characterized by abnormal proliferation of white blood cells. Although anti-cancer drugs induce apoptosis in cancerous cells, drug resistance is the significant problem mainly due to over-expression of inhibitors of apoptosis proteins [lAPs] such as survivin. In this content, it has been reported that an anti-inflammatory drug, Carbenoxolone [CBX], could induce apoptosis and growth inhibition in several types of cancerous cells. In the present study, effects of CBX on apoptosis and level of the expression of survivin gene and its deltaEx3 splicing variant have were evaluated in K562 cells. K562 cells were cultured and treated with different concentrations of CBX: [50-300 microM] at different time intervals [12-48 hrs]. Trypan blue exclusion test was used to evaluate cell viability. Fluorescent microscopy [Acridine Orange/Ethidium Bromide double staining] and DNA fragmentation assay were used to study apoptosis. The expression level of survivin and its deltaEx3 splice variant were studied by RT- PCR. It was found that both growth inhibition and apoptosis occurred in K562 cells. In addition, down-regulation of survivin and survin-deltaEx3 were observed, after 2-4 hrs treatment with 150 microM of CBX. However, the expression level of survivin and its deltaEx3 splice variant increased in subsequent time [6-12 hrs] nearly to the level of control cells. From the results of this study, it may be concluded that CBX can be considered as a candidate for further studies in CML treatment, especially in the case of drug- resistant leukemia cells
ABSTRACT
Leukemia is a malignant and progressive disorder in which genetic defects in hematopoietic cells lead to uncontrolled proliferation of blood cells. Different drugs have been proposed for the treatment of leukemia but none of them resulted in complete remission. Recently, anti-cancer effects of carbenoxolone [CBX], that is a 3- hemisuccinate, have been reported in several cell lines. In the present study we evaluated the effects of CBX on K562 cell line as an experimental model of chronic myeloid leukemia [CML]. K562 cells were cultured and treated for various time intervals with different concentrations of CBX [50-300 micro M]. Trypan blue exclusion test and tetrazolium salt absorption test [MTT] were used to evaluate the growth inhibitory and apoptotic effects of the drug. Fluorescence microscopy and DNA fragmentation assay were used to study apoptosis. The results of this study showed that CBX induced growth inhibition of K562 cells in a dose- and time- dependent manner. For example, growth inhibition rates after 48 hours treatment with concentrations of 50 micro m, 100 micro m, 150 micro m, 200 micro m and 300 micro m were 11%, 41%, 59%, 79% and 92%, respectively. Furthermore results of fluorescence microscopy and DNA fragmentation assays indicated that apoptosis, is the cause of cell death induced by CBX. Considering the growth inhibitory and apoptotic effects of CBX on human myeloid leukemia K562 cells, the drug can be considered as a potential candidate for further studies on CML treatment