Induction of apoptosis by cyclooxygenase-2 inhibitors in prostate cancer cell lines

Prostaglandins are thought to play an important role in the proliferation of prostate cancer and are highly expressed in prostate cancer tissue. Cyclooxygenase-2 (COX-2), or prostaglandin endoperoxide synthase, is a key enzyme in the conversion of arachidonic acid into prostaglandin. In several cancers, COX-2 contributes to the proliferation and metastasis of cancer cells. To assess the role of COX-2 in prostate cancer, we investigated whether the inhibition of COX-2 affected the proliferation of prostate cancer cells. The human prostate cancer cell lines, LNCaP and PC 3, and a normal prostate stromal cell line (PrSC) were treated with COX-2 inhibitors NS 398 and Etodolac. The proliferation rate of the cell lines was examined using 3(4,5-dimethylethiazoly 1-2-) 2,5-diphonyl tetrazolium bromide (MTT) assays. A DNA fragmentation assay was also used for proof of apoptosis. COX-2 inhibitors could suppress the proliferation of LNCaP and PC 3 cells. In contrast, PrSC was not affected by COX-2 inhibitors. These suppressive effects occurred in a time- and dose-dependent manner. One of mechanisms responsible for cell death was apoptosis. COX-2 seems to play a significant role in the progression of prostate cancer. COX-2 may be a therapeutic target for prostate cancer. Since COX-2 inhibitors suppress proliferation and induce apoptosis in prostate cancer cells, and have no effect in normal prostate stromal cells, COX-2 inhibitors will be useful for the treatment of prostate cancer.