Combined treatment with dissolved hydrogen molecule and platinum nanocolloid exerts carcinostatic/carcinocidal effects by increasing hydrogen peroxide generation and cell death in the human gastric cancer cell line NUGC-4.

Many studies have shown that redox regulation is an effective therapeutic strategy for different types of cancer. We have previously demonstrated that combined treatment with dissolved hydrogen molecule (H) and platinum nanocolloid (Pt-nc) has carcinostatic effects and that increased intracellular reactive oxygen species (ROS) levels were closely associated with carcinostatic effects in Ehrlich mouse ascites tumor cells. However, it is unknown whether combined treatment-induced ROS generation can occur in human cancer cells. Therefore, this study aimed to examine the carcinostatic effect of the combined treatment in human cells and investigate the relationship between treatment efficacy and ROS generation. H and Pt-nc treatment could exert cytostatic action by inhibiting the growth of human promyelocytic leukemia HL60 and human gastric adenocarcinoma-derived NUGC-4 cells; however, no effect was observed in normal human embryo fibroblast OUMS-36 cells by the temporary exposure. These findings indicate that combined treatment with H and Pt-nc may act selectively in tumor cells compared with normal cells. Additionally, combined treatment with H and Pt-nc resulted in an approximately 200-fold increase in intracellular ROS levels compared with the control, whereas the suppressive effect of tumor cell growth was abrogated entirely by catalase treatment in NUGC-4 cells. Furthermore, combined treatment with H and Pt-nc induced hydrogen peroxide generation, cellular morphological changes, cell death, and a decline in DNA synthesis-positive cells. In conclusion, combined treatment with H and Pt-nc can induce carcinostatic/carcinocidal effects through intracellular ROS increase, morphological changes, cell death, and DNA synthesis suppression in the human tumor cell line.