A gene therapy approach to enhance the targeted radiotherapy of neuroblastoma

Background. The aims of this study were to determine whether the introducti on and expression of the noradrenaline transporter (NAT) gene into NAT-nega tive neuroblastoma cell Lines would make them amenable to targeted radiothe rapy using [I-131]MIBG. Procedure. Neuroblastoma cell lines were transfecte d with a eukaryotic expression vector containing the bovine noradrenaline t ransporter cDNA under the expression of the CMV promoter. Stable transfecta nts were created by selection in geneticin (G418) and were characterised fo r their MIBG uptake ability and susceptibility to [I-131]MIBG therapy. Resu lts. The cell line SK-N-MC, which normally shows no ability to take up MIBG , was successfully transfected with bNAT. SK-N-MC.bNAT transfectants exhibi ted uptake and release kinetics similar to those of the natural NAT-express ing cell line SK-N-BE(2c). Levels of [I-131]MIBG uptake were 33% of those o f the highest naturally NAT-expressing cell line SK-N-BE(2c). Growth delay assays using multicellular spheroids indicated that this degree of [I-131]M IBG uptake was sufficient to inhibit growth at radioactive concentrations o f 4 Mbq/ml. Conclusions. These results demonstrate the feasibility of combi ning gene therapy with targeted radiotherapy to enhance uptake, and hence r adiation dose, to neuroblastoma tumours using [I-131]MIBG. With the appropr iate delivery vehicle and tumour-specific control of expression, the introd uction of noradrenaline transporter molecules may be a viable means of enha ncing the response of neuroblastoma tumours to [I-131]MIBG therapy. (C) 200 0 Wiley-Liss. Inc.