Apogossypolone induces reactive oxygen species accumulation and controls cell cycle progression in Raji Burkkit's lymphoma cells.

Burkitt's lymphoma (BL) is a highly aggressive type of non-Hodgkin's lymphoma, with marked rates of proliferation and metabolism. The expression levels of the translocated cellular Myc (c-Myc) oncogene and Epstein-Barr virus infection have an oncogenic role in facilitating tumor progression and maintaining a malignant phenotype in BL Raji cells. The present study identified that more reactive oxygen species (ROS) were produced in Raji cells compared with other types of malignant B cells. Cells exhibiting higher ROS levels suggested facilitation of the induction of cell death by ROS-induction compounds. In the present study, apogossypolone (ApoG2) was observed to induce marked accumulation in the levels of ROS in the Raji cells, which damaged the cells and suppressed cell proliferation. Within 12 h following ApoG2 treatment, the Raji cells were prominently arrested in the G1 phase of the cell cycle. Immunoblotting analysis indicated that the chromodomain-helicase-DNA-binding protein 1, checkpoint kinase 1 and c-Myc proteins were significantly downregulated at 3, 6 and 12 h, respectively, following treatment. Following treatment with ApoG2 for 48 h, ApoG2 induced significant apoptosis in the Raji cells. This findings, together with our previous studies, which demonstrated ApoG2 as a potent inhibitor of anti-apoptotic B cell lymphoma 2 proteins, indicated that the ROS stimulatory effect of ApoG2 increased the antitumor activity of ApoG2.