Recent clinical observations indicate that
ibuprofen may alleviate the radiation-induced
dysuria that almost invariably occurs during
radiation therapy for
prostate cancer. Because the use of
ibuprofen could consequently become common during
radiation therapy for
prostate cancer, we have been interested in the potential interactions between
ibuprofen and ionizing radiation on prostate
tumor cells. The effects of gamma-irradiation and/or
ibuprofen on PC3 and DU-145 human prostate
carcinoma cells were evaluated in vitro using three model systems. Clonogenic survival was determined by plating cells 24 h
after treatment of nearly confluent monolayers. Analysis of cell growth, cell detachment, and apoptotic cell death was carried out over a period of up to 9 days
after treatment of PC3 and DU-145 monolayers. The effect of
ibuprofen and/or radiation was also probed by observing the inhibition of growth of established PC3 and DU-145 colonies that were treated on the 14th day of colony growth.
Ibuprofen enhanced the radiation response of
prostate cancer cells in all three in vitro models. Both the cytotoxic and
radiosensitizing effects of
ibuprofen seem to require concentrations that are higher than those reported to inhibit
prostaglandin synthesis, suggesting that other molecular mechanisms may be responsible for
ibuprofen cytotoxicity.