Simvastatin and purine analogs have a synergic effect on apoptosis of chronic lymphocytic leukemia cells.
Despite many therapeutic regimens introduced recently, chronic lymphocytic leukemia (CLL) is still an incurable disorder. Thus, there is an urgent need to discover novel, less toxic and more effective drugs for CLL patients. In this study, we attempted to assess simvastatin, widely used as a cholesterol-lowering drug, both as a single agent and in combination with purine analogs-fludarabine and cladribine-in terms of its effect on apoptosis and DNA damage of CLL cells. The experiments were done in ex vivo short-term cell cultures of blood and bone marrow cells from newly diagnosed untreated patients. We analyzed expression of active caspase-3 and the BCL-2/BAX ratio as markers of apoptosis and the expression of phosphorylated histone H2AX (named γH2AX) and activated ATM kinase (ataxia telangiectasia mutated kinase), reporters of DNA damage. Results of our study revealed that simvastatin induced apoptosis of CLL cells concurrently with lowering of BCL-2/BAX ratio, and its pro-apoptotic effect is tumor-specific, not affecting normal lymphocytes. We observed that combinations of simvastatin+fludarabine and simvastatin+cladribine had a synergic effect in inducing apoptosis. Interestingly, the rate of apoptosis caused by simvastatin alone and in combination was independent of markers of disease progression like ZAP-70 and CD38 expression or clinical stage according to Rai classification. We have also seen an increase in γH2AX expression in parallel with activation of ATM in most of the analyzed samples. The results suggest that simvastatin can be used in the treatment of CLL patients as a single agent as well as in combination with purine analogs, being equally effective both in high-risk and good-prognosis patients. One of the mechanisms of simvastatin action is inducing DNA damage that ultimately leads to apoptosis.
Podhorecka
Monika
M
Department of Haematooncology and Bone Marrow Transplantation, Medical University of Lublin, Staszica 11, Lublin, Poland. monika.podhorecka@am.lublin.pl
Halicka
Dorota
D
Klimek
Piotr
P
Kowal
Malgorzata
M
Chocholska
Sylwia
S
Dmoszynska
Anna
A
D051997:ADP-ribosyl Cyclase 1 / Q000378:metabolism; D000924:Anticholesteremic Agents / Q000494:pharmacology; D000970:Antineoplastic Agents / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects; D064007:Ataxia Telangiectasia Mutated Proteins; D053148:Caspase 3 / Q000378:metabolism; D018797:Cell Cycle Proteins / Q000378:metabolism; D017338:Cladribine / Q000494:pharmacology*; D004268:DNA-Binding Proteins / Q000378:metabolism; D004789:Enzyme Activation; D006657:Histones / Q000378:metabolism; D006801:Humans; D015451:Leukemia, Lymphocytic, Chronic, B-Cell / Q000188:drug therapy / Q000378:metabolism*; D011379:Prognosis; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism; D011687:Purines / Q000737:chemistry / Q000494:pharmacology; D019821:Simvastatin / Q000494:pharmacology*; D014407:Tumor Cells, Cultured / Q000187:drug effects*; D025521:Tumor Suppressor Proteins / Q000378:metabolism; D014740:Vidarabine / Q000031:analogs & derivatives* / Q000494:pharmacology; D051746:ZAP-70 Protein-Tyrosine Kinase / Q000378:metabolism; D051028:bcl-2-Associated X Protein / Q000378:metabolism
D000924:Anticholesteremic Agents; D000970:Antineoplastic Agents; D018797:Cell Cycle Proteins; D004268:DNA-Binding Proteins; C468783:H2AX protein, human; D006657:Histones; D019253:Proto-Oncogene Proteins c-bcl-2; D011687:Purines; D025521:Tumor Suppressor Proteins; D051028:bcl-2-Associated X Protein; D017338:Cladribine; D019821:Simvastatin; D051746:ZAP-70 Protein-Tyrosine Kinase; C497261:ZAP70 protein, human; C576324:ATM protein, human; D064007:Ataxia Telangiectasia Mutated Proteins; D017346:Protein Serine-Threonine Kinases; D051997:ADP-ribosyl Cyclase 1; D053148:Caspase 3; D014740:Vidarabine; C024352:fludarabine