Recent studies indicate that ascorbic acid (AA), known as vitamin C may improve the clinical outcome of arsenic trioxide (As2O3) for patients with acute promyelocytic leukemia (APL). However, the mechanisms by which chemotherapy drugs work remain largely unknown. Therefore, the aim of the present investigation was to use human leukemia (HL-60) APL-cells as an in vitro test model to find out whether the combination of ascorbic acid (vitamin C) and arsenic trioxide (Trisenox) is effective in the treatment of patients who have APL. To achieve this goal, we performed the trypan blue exclusion test for cell viability, lipid hydroperoxide assay for assessing the levels of the degradation products of polyunsatured fatty acid (PUFA) hydroperoxide generation, flow cytometry analysis for apoptosis, and confocal fluorescent microscope for morphological changes. The results of the trypan blue exclusion test indicated that AA treatment potentiates the cytotoxicity of As2O3 in HL-60 cells, as evidenced by a gradual increase in lipid hydroperoxide levels with increasing doses of AA. The flow cytometry analysis showed a strong dose-response relationship with regard to ascorbic acid co-treatment with arsenic trioxide and apoptosis as characterized by the percentages of annexin V positive. The addition of ascorbic acid with arsenic trioxide led to impressive morphological changes in co-treated cells compared to the control group. Taken together, this in vitro study provides evidence that a physiological dose of ascorbic acid is sufficient to potentiate As2O3-induced toxicity and apoptosis in HL-60 cells, at least in part through, induction of oxidative stress, activation of phosphatidylserine externalization and morphological changes. This finding indicates that ascorbic acid represents a therapeutic potential in APL by being a sensitizer or an adjunct to As2O3.

Citation Information: In: Proc Am Assoc Cancer Res; 2009 Apr 18-22; Denver, CO. Philadelphia (PA): AACR; 2009. Abstract nr 5479.

100th AACR Annual Meeting-- Apr 18-22, 2009; Denver, CO

American Association for Cancer Research
2009