The Growth-inhibitory and Apoptosis-inducing Effect of Deferoxamine Combined with Arsenic Trioxide on HL-60 Xenografts in Nude Mice

Objective: The aim of this study is to investigate the growth-inhibitory and apoptosis-inducing effect of deferoxamine (DFO) combined with arsenic trioxide (ATO) on the human HL-60 xenografts in nude mice and its mechanism.

Method: The highly tumorigenic leukemia cell line HL-60 cells were inoculated subcutaneously into nude mice to establish a human leukemia xenograft model. The HL-60 xenograft nude mice models were randomly divided into four groups: control (Normal saline, NS), 50mg/kg DFO, 3mg/kg ATO, the combined treatment (50mg/kg DFO+1.5mg/kg ATO) once HL-60 cells were inoculated. Tumor sizes, growth curves, inhibitory rates, cell apoptosis, and the expression of apoptosis related markers were measured to evaluate the tumor growth.

Results: Xenografted tumors were observed in all nude mice since the 5th day of inoculation. The inhibitory rates of tumor weight were 2.67%, 10.69%, and 25.57% in DFO, ATO and combination therapy groups, respectively. The combination of DFO with ATO induces significantly more tumor cell apoptosis than either agent alone (p<0.05). The expression of NF-κBp65 and survivin proteins decreased significantly while the expression of Caspase-3 and Bax increased in the combination therapy group (p<0.05). Double immunofluorescence for Caspase-3 and NFκBp65 demonstrated an inverse relationship between Caspase-3-positive areas and NFκBp65-positive areas, as well as the co-localization of Bax and survivin in xenografted tumor cells.

Conclusions: Combination of DFO and ATO has synergistic effects on tumor growth inhibition and apoptosis-inducing in vivo with no significant side effects. The DFO and ATO can up-regulate the expression of Caspase-3 and Bax, and down-regulate the expression of NF-κBp65 and survivin, especially for their combination.