Recovery of urothelial mediator release but prolonged elevations in interleukin-8 and nitric oxide secretion following mitomycin C treatment

Intravesical mitomycin C (MMC) is commonly used to treat bladder cancer but is associated with local adverse effects. Here, we investigate the effects of MMC on release of urothelial mediators and production of inflammatory cytokines. Recovery and the effects of repeat treatment were also investigated. Urothelial cells were treated with MMC for 2 h at 37 °C. Immediately, 24 h and 7 days following MMC treatment, effects were assessed in terms of changes in ATP, acetylcholine and PGE₂ release, and the presence of inflammatory cytokines and nitric oxide in incubation medium. Endpoints were also assessed 7 days after repeat MMC treatment. Immediately following MMC treatment at the clinical concentration (2 mg/mL), stretch-induced ATP release was significantly decreased, basal acetylcholine release was enhanced, while basal PGE₂ was depressed and response to stretch increased. Twenty-four hours after treatment, basal acetylcholine was significantly increased ([MMC] ≥0.0002 mg/mL) and basal PGE₂ enhanced (0.02 mg/mL). A 326-fold increase in interleukin-8 secretion and significant increase in nitric oxide release were also detected at 24 h. One week after single and repeat MMC treatment, urothelial ATP, acetylcholine and PGE₂ had recovered while the increase in nitric oxide and interleukin-8 was still evident. These results indicate that urothelial mediator release is affected by MMC treatment with full recovery by 1 week. However, a concurrent increase in secretion of the inflammatory cytokine interleukin-8 and nitric oxide was also detected 24 h following treatment, which were still evident after the recovery period. These changes may play a role in the local adverse effects associated with intravesical MMC treatment.