Rotenone, Rhodamine 123, and Janus Green Induce Damage to Nuclear DNA in Ascites Tumor Cells from Mice. Rotenone and Rhodamine in X-Ray Irradiated Cells Contribute to the Maintenance of Genome Integrity

The mitochondrial inhibitors rotenone and rhodamine 123 and the Janus Green B dye are being studied in order to develop pharmacological agents that cause mitochondrial dysfunction and apoptosis. Since mitochondrial dysfunction is associated with the production of reactive oxygen species, it seems relevant to compare the DNA damage induced by these substances to cells of ascitic Ehrlich carcinoma and murine lymphocytic leukemia P388 with exposure to a known inducer of reactive oxygen species, that is, ionizing (X-ray) radiation. The level of DNA damage was assessed using an alkaline version of the Comet assay. The level of DNA damage induced by rotenone was comparable to irradiation at a dose of 4 Gy in both cell types. Post-radiation incubation reduced the level of DNA damage, which indicates DNA repair. Treatment of Ehrlich’s ascitic carcinoma cells with rhodamine 123 followed by washing did not cause this increase; however, irradiation at a dose of 4 Gy in the presence of rhodamine 123 induced an increase in the level of DNA damage, which significantly decreased after 1 h incubation. It can be assumed that pretreatment of cells with rotenone and rhodamine 123, which impair the work of mitochondria, contributed to the preservation of the integrity of nuclear DNA in irradiated cells. Exposure to Janus Green B caused increased DNA damage and cell death. Based on the alkaline version of the Comet assay, damage induced by these compounds can be considered as single- and double-strand breaks and alkali-labile (apurine/apirimidine) sites in DNA.