Bcl-2 Inhibition Induces a Synergistic Effect in Combination with Doxorubicin in Chronic Lymphocytic Leukemia

Abstract

Background: Chronic lymphocytic leukemia (CLL), a common neoplastic disease, is associated with the accumulation of B-lymphocytes in the hematopoietic organs. A main characteristic of CLL cells is the failure to undergo apoptosis, thus resulting in resistance to several chemotherapeutics. Doxorubicin (DOX), an anthracycline widely used for treating various neoplasms including CLL, induces apoptosis via several mechanisms. Despite this, CLL cells become resistant to DOX. A major protein known as B-cell lymphoma-2 (Bcl-2), known to exert direct anti-apoptotic effects on the cell, is reported to be overexpressed in CLL cells. Methods: We aimed to silence the Bcl-2 gene by siRNA. Mononuclear cells were isolated from the peripheral blood and bone marrow of eleven untreated CLL patients by Ficoll-Paque. To transfect cells, we used Lipofectamine. Bcl-2 expression was investigated using qRT-PCR. Next, we studied the effect of Bcl-2 silencing in combination with DOX treatment on the viability of cells by an MTT (3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide) assay. Results: Bcl-2 expression was significantly suppressed in CLL cells following siRNA transfection via lipofectamine. Based on the results of MTT, the inhibition of Bcl-2 sensitized CLL cells to DOX treatment. Also, the effect of the treatment was time-dependent. Conclusion: These findings imply that combination therapy of CLL using anti-Bcl-2 siRNA and DOX can be considered a practical therapeutic approach that should be further evaluated in future studies.

Keywords

• cll
• doxorubicin
• bcl-2
• leukemia
• sirna
• chemoresistance