Targeted Detection of Cyclooxygenase-1 in Ovarian Cancer

Overexpression of cyclooxygenase-1 (COX-1) is associated with the initiation and progression of ovarian cancer, and targeted imaging of COX-1 is a promising strategy for early detection of this disease. We report the discovery of N-[(5-carboxy-X-rhodaminyl)but-4-yl]-3-(1-(4-methoxyphenyl)-5-(p-tolyl)-1H-pyrazol-3-yl)propenamide (CMP) as the first COX-1-targeted optical agent for imaging of ovarian cancer. CMP exhibits light emission at 604 nm (λ_max), thereby minimizing tissue autofluorescence interference. In both purified enzyme and COX-1-expressing human ovarian adenocarcinoma (OVCAR-3) cells, CMP inhibits COX-1 at low nanomolar potencies (IC₅₀ = 94 and 44 nM, respectively). CMP's selective binding to COX-1 in OVCAR-3 cells was visualized microscopically as intense intracellular fluorescence. In vivo optical imaging of xenografts in athymic nude mice revealed COX-1-dependent accumulation of CMP in COX-1-expressing mouse ovarian surface epithelial carcinoma (ID8-NGL) and OVCAR-3 cells. These results establish proof-of-principle for the feasibility of targeting COX-1 in the development of new imaging and therapeutic strategies for ovarian cancer.