The role of reactive oxygen species in combination therapy of 5-FU and celecoxib in head and neck squamous cell carcinoma

Abstract

Introduction: The role of celecoxib in preventing and treating tumors has attracted broad attention in recent years because of its selective and specific inhibition of COX-2 activity. We investigated the inhibitory effects and mechanisms of celecoxib combined with 5-FU on proliferation of squamous cell carcinoma cells in vivo and in vitro.

Methods: SNU-1041 and SNU-1076 squamous cell lines and an orthotopic tongue cancer mouse model were used to study growth inhibition with 5-FU enhanced by celecoxib. Sensitivity of cells to drug treatment was analyzed by the MTT assay, and generation of reactive oxygen species (ROS) was measured using dichlorofluorescein diacetate (DCFH-DA). Phosphorylation of AKT was detected by Western blotting. Survival analysis in the mouse model was assessed according to combination treatment with 5-FU and celecoxib.

Results: ROS production in vitro was highest when celecoxib was administered 48 hours after 5-FU treatment. 5-FU-induced inhibition of cell proliferation was enhanced when combined with celecoxib, which was positively correlated with ROS production. Antioxidant treatment reversed 5-FU-inhibited cell proliferation by up to 60%. Co-treatment with celecoxib and 5-FU partially blocked AKT phosphorylation, although no significant changes in total AKT protein levels were detected. An increased survival time was observed in an orthotopic mouse model treated with a combination of celecoxib and 5-FU compared to treatment with either agent alone.

Conclusions: Celecoxib may have an enhanced anticancer effect in combination with 5-FU. ROS production may be a key mechanisms in this combination therapy by inhibiting the AKT pathway.