Efficacy of 5-fluorouracil on Tumor Growth in Walker -256 Xenografted rat. Mice is dependent on Circadian Rhythm

Abstract

Chronotherapy is one of the most active treatment schedule, based on the adjustment of drug delivery to the 24-hour rhythms generated by circadian rhythm. The aim of this study is to confirm that the efficacy of 5-fluorouracil (5-FU) is dependent on circadian rhythm, using Walker-256 xenografted rat. The present study demonstrated that tumor developed more rapidly at night rather than at day. Moreover, the administration of 5-FU at night was more effective rather than that at day. Furthermore, the microvessel count by immunohistochemical staining of endothelial cells revearled that tumors treated with 5-FU at night contained significantly less microvessels than those at day. In conclusion, our present data suggested that chronotherapy would contribute to the improvement of chemotherapy in patients with some population of malignancy through the control of angiogenesis.