Gemcitabine treatment of experimental C6 glioma: the effects on cell cycle and apoptotic rate.

Gemcitabine (dFdCyd) is a deoxycytidine analogue showing a broad spectrum of cytotoxic activity; additionally, at non-cytotoxic concentrations, it is a potent radiosensitiser. Its in vitro and in vivo effects were studied on C6 rat glioma. In vitro, dFdCyd induced an increase in S-phase cells at the end of treatment, with a reduction in G1 and G2 cell cycle-phase cells and relevant effects on the apoptotic rate. The in vivo effects of dFdCyd were studied on rats bearing intracranial C6 glioma. The drug was administered at a dose of 120 mg/Kg every 3 days x 4 doses. A significant effect on tumour growth was detected by longitudinal MRI analyses. Furthermore, the drug induced an inhibitory effect on tumour growth, 72 h after a 300 mg/Kg single dose. Analyses performed on tumour specimens showed relevant G1-phase accumulation and about 45% apoptotic cells. The present results justify further studies to determine the potential efficacy of dFdCyd in the treatment of malignant gliomas.