COX-2 targeting and hypoxia activation of IMC-NTR for cancer diagnosis and therapeutics: In vitro and in vivo studies

A significant challenge in cancer diagnosis and treatment lies in tumor heterogeneity and the insufficient specificity of biomarkers such as cyclooxygenase-2 (COX-2) and nitroreductase (NTR), which often limits the efficacy of conventional therapies. To address this, we developed a novel theranostic probe, IMC-NTR, designed to selectively target COX-2 and NTR under hypoxic conditions, enabling both real-time fluorescence imaging of cancer progression and inhibition of metastasis. IMC-NTR was rationally constructed by conjugating indomethacin (IMC), a selective COX-2 inhibitor, with a nitro-functionalized naphthalimide that undergoes NTR-mediated bioreduction under hypoxia, resulting in a significant fluorescence turn-on at 534 nm. The probe exhibited high selectivity and sensitivity for NTR over other biologically relevant species, with a 22-fold signal-to-noise ratio, and a detection limit of 0.0211 μg/mL. The cancer-targeting ability of IMC-NTR was validated in vitro using COX-2 positive A549 lung cancer cells and in vivo in zebrafish models. Furthermore, wound-healing and invasion assays demonstrated that IMC-NTR effectively suppressed cancer cell migration and invasion, both of which are critical processes in metastasis. In zebrafish, IMC-NTR specifically localized to the intestine, a COX-2-enriched organ, confirming its in vivo targeting specificity and biological relevance. Taken together, these results suggest that IMC-NTR enables sensitive detection of NTR activity under hypoxia and holds promise as a dual-function agent for cancer imaging and therapeutic intervention. Further studies are warranted to assess its clinical potential and to address limitations related to potential off-target interactions.