Microfluorocytometric detection of nuclear DNA damage to cancer cells in squamous cell carcinoma after hyperthermia.
An 84-year-old woman had a squamous cell carcinoma on her left thigh. Before operation, half of the tumor mass was irradiated with a microwave at 43 degrees C for an hour. After the hyperthermia, the tumor mass was removed, and the DNA instability was investigated by microfluorocytometric measurement of the cells stained with pararosaniline-Feulgen after hydrolysis with 2N HCl at 30 degrees C. The kinetic parameters k1, which is the rate constant for the generation of an apurinic acid, k2, which is the rate constant for the depolymerization of the apurinic acid and which reflects the degree of DNA instability for acid hydrolysis, and y0, which is the theoretical value of the single-stranded DNA present initially and reflects the degree of DNA damage, were determined by a computer fitting of the Bateman function to the hydrolysis curve plotting of the fluorescence intensity of the pararosaniline-Feulgen staining the apurinic acid against the different hydrolysis times. The parameter values y0 and k2 of the cells treated by hyperthermia were much higher than those of the cells treated without hyperthermia. It is our conclusion that this microfluorometric detection would be valuable as an evaluation method for a cancer therapy, although more data from other cancers and treatments will be needed.