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Effects of quinacrine combined with thioridazine on inducing apoptosis of chronic myelogenous leukemia cells

TU Yao-yao, XU Han-zhang, LEI Hu, WU Ying-li   

  1. Department of Pathophysiology, the Key Laboratory of Cell Differentiation and Apoptosis of the Chinese Ministry of Education, Basic Medicine Faculty of Shanghai Jiao Tong University, Shanghai 200025, China
  • Online:2014-07-28 Published:2014-08-11

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Abstract:

Objective To study the effects of Quinacrine (QC) and Thioridazine (THZ) on chronic myelogenous leukemia (CML) cells (K562 cells). Methods K562 cells were treated by different concentrations of QC (0, 1, 2, 3, and 4 μmol/L) and THZ (0, 2, 4, 8, and 16 μmol/L) for 0, 24, and 48 h. The effects of each drug on the viability of cells were examined by the trypan blue exclusion assay. Then K562 cells were treated by different concentrations of QC (2, 3, and 4 μmol/L) and THZ (2, 4, and 8 μmol/L) for 24 h alone or in combination. The viability of cells was examined by the trypan blue exclusion assay. The combinational index was calculated by the CompuSyn software. Next K562 cells were treated by QC of 3 μmol/L and THZ of 4 μmol/L for 24 h alone or in combination, with or without being treated by pancaspase inhibitor Z-VAD-FMK of 20 μmol/L. Variations of the mitochondrial transmembrane potential were detected by the Rh123/PI staining and flow cytometry. Apoptosis related proteins were detected by the Western blotting. Results Results of the trypan blue exclusion assay indicated that being treated by QC or THZ of low concentrations alone had no significant influence on the viability of K562 cells, while being treated by QC combined with THZ had a good synergistical effect on inducing death of K562 cells. Results of the Western blotting showed that the cleavage of PARP-1 and the reduction of expressions of apoptosis-related proteins Mcl-1 and Bcl-2 were induced after being treated by two drugs in combination and could not be reversed by Z-VAD-FMK. Results of the flow cytometry showed that compared to being treated by one drug, the mitochondrial transmembrane potential of K562 cells treated by QC of 3 μmol/L and THZ of 4 μmol/L in combination for 24 h was significantly decreased and could not be reversed by Z-VAD-FMK. Conclusion QC plus THZ can synergistically induce caspase-independent apoptosis of K562 cells. The decrease of mitochondrial transmembrane potential may involve in this process.

Key words: chronic myelogenous leukemia, Quinacrine, Thioridazine, synergistic action, mitochondrial membrane potential