We investigated the possible modulation by LOX/ COX inhibitors of all-trans retinoic acid (ATRA)-induced cell differentiation in two established neuroblastoma cell lines, SH-SY5Y and SK-N-BE(2). Caffeic acid, as an inhibitor of 5-lipoxygenase, and celecoxib, as an inhibitor of cyclooxygenase-2, were chosen for this study. The effects of the combined treatment with ATRA and LOX/COX inhibitors on neuroblastoma cells were studied using cell morphology assessment, detection of differentiation markers by immunoblotting, measurement of proliferation activity, and cell cycle analysis and apoptosis detection by flow cytometry. The results clearly demonstrated the potential of caffeic acid to enhance ATRA-induced cell differentiation, especially in the SK-N-BE(2) cell line, whereas application of celecoxib alone or with ATRA led predominantly to cytotoxic effects in both cell lines. Moreover, the higher sensitivity of the SK-N-BE(2) cell line to combined treatment with ATRA and LOX/COX inhibitors suggests that cancer stem cells are a main target for this therapeutic approach. Nevertheless, further detailed study of the phenomenon of enhanced cell differentiation by expression profiling is needed.

Laboratory of Tumor Biology and Genetics Institute of Experimental Biology School of Science Masaryk University 61137 Brno Czech Republic

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Enhancement of ATRA-induced differentiation of neuroblastoma cells with LOX/COX inhibitors: an expression profiling study