A novel celecoxib derivate, OSU03012, induces caspase-dependent cytotoxicity and cell cycle arrest in neuroblastoma

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Neuroblastomas express cyclooxygenase 2(COX-2) and celecoxib has been shown to induce apoptosis in vitro and in vivo. However, NSAID have shown to be efficient inhibitors of tumour growth both in cancer cells with and without COX-2 expression. OSU03012 is a bioavailable third-generation celecoxib derivate lacking COX-2 inhibitory activity that potently induces apoptosis in a variety of cancer cell lines possibly through the inhibition of phosphatidylinositol 3-kinase (PI3K)/AKT. Immunohistochemical staining of neuroblastoma tumours using phospo-specific antibodies revealed that a majority of clinical neuroblastomas exhibit high levels of phosphorylated AKT in their tumour cells. No AKT-phosporylation was detected in adrenal medullas from healthy children. Hence, we assessed the ability of OSU03012 to inhibit neuroblastoma tumour growth. Neuroblastoma cell lines treated with OSU03012 displayed aconcentration-dependent decrease in cell viability.The concentration of OSU03012 that was associated with 50%inhibition of neuroblastoma cell growth (biologicIC₅₀) ranged from 0,3-1,5 μM. OSU03012 induced depolarisation of the mitochondrial transmembrane potential, activation of caspase-9, PARP and induction of apoptosis as shown by western blot and FACS analysis. Moreover, cell cycle analysis revealed a pronounced S-phase arrest of OSU03012 treated neuroblastoma cells. These results provide support for further testing of OSU03012 in the treatment of childhood neuroblastoma.