Background: Acute lymphoblastic leukemia (ALL) is the most common type of cancer in children. Currently, chemotherapy is the most effective method of leukemia cancer treatmentwhich has many side effects. New strategies in cancer therapy utilizecompounds that specifically target aberrant signaling pathways in order to reduce toxic sideeffects Indole-3-carbinl (I3C) found in vegetables has multiple anti-cancer properties because of its ability to modulate multiple cellular signaling pathways. In this study the molecular mechanism of the action of indole-3-carbinol on pre- B ALL cells was investigated.

Materials and Methods: In current study, NALM-6 cells were treated with different concentrations of I3C at specific times. Analysis of cellular DNA content was performed by flow cytometry for evaluation of cell cycle status. The protein expression of p21, p53 as well as c-Myc proteins was determined by Western blot in I3C-treated cells.

Results: Cell cycle histogram analysis showed that I3C significantly increased the percentage of G1 cells compared with non-treated cells (control)(p<0.05). The western blot analysis also indicated I3C significantly up regulated p21, p53 expression and down regulated c-Myc expression (p<0.05).

Conclusion: The G1 arrest induced by I3C is associated with down-regulation of c-Myc and up-regulation of p53 and its downstream target p21.

Background: Doxorubicin is a chemotherapeutic agent still in widespread use in hematologic malignancies. A side effect of anthracyclines such as doxorubicin is the activation of nuclear factor-&kappaB (NF-&kappaB), a potent inducer of antiapoptotic genes, which may blunt the therapeutic efficacy of the drugs. In this study, the effect of indole -3-carbinol (I3C) on the activation NF-&kappaB and the anti-apoptotic genes whose expression is regulated by NF-&kappaB was assessed in NALM-6 cells.

Materials and Methods: NALM-6 cells were preincubated with various concentrations of I3C and then treated with doxorubicin. Cellular DNA content assay and Annexin V-FITC staining were performed by flowcytometry for evaluation of apoptosis. For assessing the effect of I3C on the expression of XIAP, survivin, and nuclear p65 proteins, NALM-6 cells were pretreated with I3C and then incubated with doxorubicin. Whole-cell and nuclear extracts were prepared for Western blot analysis. A paired t-test was conducted to evaluate the results.

Results: DNA histogram analysis of NALM-6 cells indicates a combination of I3C with doxorubicin significantly escalated the percentages of sub-G1 population cells compared with doxorubicin - only treated group (p<0.05). Annexin V-FITC staining also showed that cotreatment of NALM-6 cells with I3C and doxorubicin significantly increased the proportion of Annexin-V positive cells in comparison with the doxorubicin treated cells (p<0.05). The western blot analysis indicated I3C significantly inhibits both doxorubicin -induced nuclear translocation of p65 and the expression of doxorubicin-induced NF-&kappaB target.

Conclusion: Our results indicated that using natural non-toxic inhibitors of NF-&kappaB such as I3C in combination with anthracyclines might be a rational combination therapy for BCP-ALL cells in which NF-&kappaB is constitutively active.