Cytotoxic activity of valproic acid on primary chronic lymphocytic leukemia cells.
BACKGROUND
Chronic lymphocytic leukemia (CLL) is the most common adult leukemia in western civilization. The accumulation of CD5+CD19+ B lymphocytes in peripheral blood is due to a defect in the apoptotic pathway rather than excessive proliferation in the bone marrow and lymph nodes. Despite a number of treatments, CLL remains an incurable disease. Valproic acid (VPA) activity, as a histone deacetylase inhibitor, could restore the epigenetic changes underlying the pathogenesis of CLL and thus induce cell death.


OBJECTIVE
In the present study we hypothesized that VPA could induce CLL primary cells death through activation of apoptosis.


METHODS
Peripheral blood samples were obtained from 53 CLL patients. Peripheral blood mononuclear cells were isolated through density gradient centrifugation and were the subject of a 24-hour cell culture with 10 mM of VPA. The cytotoxic effect of VPA was evaluated with an XTT test and thereafter confirmed using Annexin V-FITC/PI staining and flow cytometry techniques.


RESULTS
In this study, a median VPA cytotoxicity of 13.88% with a range of 0-54.65% was observed. Annexin V/PI staining confirmed that the demonstrated cytotoxicity was caused by increased apoptosis in the VPA treated cells as compared to control cells. Statistical analysis showed that VPA's effect on CLL cells depends on lactate dehydrogenase serum levels, but is independent of all other prognostic markers.


CONCLUSIONS
The results of the present experiments found that VPA at a clinically applicable concentration significantly induces apoptosis independently of the disease stage and might be a valuable therapeutic agent for all CLL patients.
Department of Experimental Hematooncology, Medical University of Lublin, Poland.
Marta
M
Karp
Department of Hematooncology and Bone Marrow Transplantation, Medical University of Lublin, Poland.
Kamila
K
Kosior
Department of Experimental Hematooncology, Medical University of Lublin, Poland.
Agnieszka
A
Karczmarczyk
Department of Experimental Hematooncology, Medical University of Lublin, Poland.
Małgorzata
M
Zając
Department of Experimental Hematooncology, Medical University of Lublin, Poland.
Joanna
J
Zaleska
Department of Hematooncology and Bone Marrow Transplantation, Medical University of Lublin, Poland.
Waldemar
W
Tomczak
Department of Hematooncology and Bone Marrow Transplantation, Medical University of Lublin, Poland.
Sylwia
S
Chocholska
Department of Hematooncology and Bone Marrow Transplantation, Medical University of Lublin, Poland.
Marek
M
Hus
Department of Hematooncology and Bone Marrow Transplantation, Medical University of Lublin, Poland.
Anna
A
Dmoszyńska
Department of Experimental Hematooncology, Medical University of Lublin, Poland; Department of Hematooncology and Bone Marrow Transplantation, Medical University of Lublin, Poland.
Krzysztof
K
Giannopoulos
D000368:Aged; D000369:Aged, 80 and over; D017304:Annexin A5; D017209:Apoptosis / Q000187:drug effects; D003603:Cytotoxins / Q000494:pharmacology*; D005260:Female; D016650:Fluorescein-5-isothiocyanate; D056572:Histone Deacetylase Inhibitors / Q000494:pharmacology*; D006801:Humans; D007770:L-Lactate Dehydrogenase / Q000097:blood; D015451:Leukemia, Lymphocytic, Chronic, B-Cell / Q000097:blood / Q000201:enzymology / Q000473:pathology; D007963:Leukocytes, Mononuclear / Q000187:drug effects* / Q000201:enzymology / Q000473:pathology; D008297:Male; D008875:Middle Aged; D061251:Primary Cell Culture; D014635:Valproic Acid / Q000494:pharmacology*
D017304:Annexin A5; D003603:Cytotoxins; D056572:Histone Deacetylase Inhibitors; D014635:Valproic Acid; D007770:L-Lactate Dehydrogenase; D016650:Fluorescein-5-isothiocyanate