Antiproliferative and Apoptosis-Inducing Activities of Thymoquinone in Lymphoblastic Leukemia Cell Line.

Acute lymphoblastic leukemia is one of the malignant proliferations of lymphoid cells in the early stages of differentiation and accounts for about 80% of all cases of childhood leukemia. Side effects of available treatment are still main concern. Thymoquinone (TQ), a natural compound isolated from Nigella sativa , induces growth inhibition and apoptosis in several cancer cell lines. The aim of the present study was to investigate the effect of TQ alone and in combination with doxorubicine on the proliferation inhibition and apoptosis induction of TQ in a lymphoblastic leukemia cell line. Jurkat cell line was cultured in standard condition and with concentrations of TQ (0-30 μm) and doxorubicine for 24, 48 and 72 h. Cell viability was measured by MTS assay. Apoptosis induction by TQ was assessed by annexin V-FITC/PI and flow cytometry analysis. TQ and DOX decreased cell viability with a time and dose dependent manner. The IC50 values were 19.461 ± 1.141, 17.342 ± 1.949 and 14.123 ± 1.874 μM in 24, 48 and 72 h, respectively for TQ. IC50 values for DOX were. 075 ± .0124, .028 ± .007 and.007 ± .001 μM in 24, 48 and 72 h, respectively. The level of cell apoptosis in all used concentrations of TQ (4, 8, 12, 16 and 20 μm) was higher than control group (10.2, 14.1, 36.6, 87.5 and 93.3% respectively after 24 h; 10.7, 13.9, 64.6, 92.2 and 93.1 respectively after 48 h; 2.83, 5.83, 41.4, 71.6 and 86.6% respectively after 72 h) and reached to a significant level at 12, 16 and 20 μm concentration for 24 and 48 h and 16 and 20 μm for 72 h incubation. Combination of doxorubicine and TQ lead to a synergistic cytotoxicity as compared to any of them alone. The study indicated that TQ is effective on proliferation inhibition and is a strong apoptotic inducer in Jurkat lymphoblastic cell line and has synergistic effect in combination with DOX. This combination strategy can be an alternative way for more powerful anticancer effects. Therefore, the study of the mechanism of apoptosis induction of TQ can be a step forward to in target therapy which might be considered in the future studies.