The use of hydrogen peroxide to enhance the efficacy of doxorubicin hydrochloride in a murine bladder tumor cell line

Purpose: We determined whether the cytotoxicity of doxorubicin hydrochlorid e would be enhanced by adding hydrogen peroxide as a source of oxygen free radicals. Materials and Methods: Mouse bladder tumor cells (MBT-2) were grown in RPMI 1640 medium and treated with various concentrations of doxorubicin hydroch loride for 2 hours. Protein content was assayed as a measure of cell growth . A similar set of experiments was done with cells exposed to hydrogen pero xide only and combined doxorubicin and hydrogen peroxide. Protein content w as again assayed as a measure of cell growth. Cells were also assayed for g lutathione peroxidase and malonyl dialdehyde, a product of lipid peroxidati on, to determine the mechanism of cell damage. Furthermore, MBT-2 cells wer e incubated with 100 M. alpha -tocopherol, a free radical scavenger, before exposure to hydrogen peroxide to determine whether the effects of hydrogen peroxide could be reversed. Results: We observed a dose dependent inhibition of MBT-2 cell growth after exposure to doxorubicin hydrochloride. Exposure to doxorubicin and hydroge n peroxide resulted in greater cell growth inhibition than exposure to eith er agent alone. The effects of hydrogen peroxide on cell proliferation were reversed by pre-incubation with alpha -tocopherol. Conclusions: As a source of oxygen free radicals, hydrogen peroxide enhance s the antiproliferative effect of doxorubicin hydrochloride on a mouse blad der tumor cell Line. Thus, hydrogen peroxide may be a relatively inexpensiv e, nontoxic method of augmenting the cytotoxicity of doxorubicin hydrochlor ide. Further studies are warranted to determine whether these observations may have clinical application.