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An efficient targeted radiotherapy/gene therapy strategy utilising human telomerase promoters and radioastatine and harnessing radiation‐mediated bystander effects
Author(s) -
Boyd Marie,
Mairs Robert J.,
Keith W. Nicol,
Ross Susan C.,
Welsh Philip,
Akabani Gamal,
Owens Jonathan,
Vaidyanathan Ganesan,
Carruthers Ross,
Dorrens Jennifer,
Zalutsky Michael R.
Publication year - 2004
Publication title -
the journal of gene medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.689
H-Index - 91
eISSN - 1521-2254
pISSN - 1099-498X
DOI - 10.1002/jgm.578
Subject(s) - bystander effect , cancer research , transfection , telomerase , radiation therapy , promoter , genetic enhancement , telomerase reverse transcriptase , gene , microbiology and biotechnology , chemistry , biology , gene expression , nuclear medicine , medicine , immunology , genetics
Abstract Background Targeted radiotherapy achieves malignant cell‐specific concentration of radiation dosage by tumour‐affinic molecules conjugated to radioactive atoms. Combining gene therapy with targeted radiotherapy is attractive because the associated cross‐fire irradiation of the latter induces biological bystander effects upon neighbouring cells overcoming low gene transfer efficiency. Methods We sought to maximise the tumour specificity and efficacy of noradrenaline transporter (NAT) gene transfer combined with treatment using the radiopharmaceutical meta‐[ 131 I]iodobenzylguanidine ([ 131 I]MIBG). Cell‐kill was achieved by treatment with the β‐decay particle emitter [ 131 I]MIBG or the α‐particle emitter [ 211 At]MABG. We utilised our novel transfected mosaic spheroid model (TMS) to determine whether this treatment strategy could result in sterilisation of spheroids containing only a small proportion of NAT‐expressing cells. Results The concentrations of [ 131 I]MIBG and [ 211 At]MABG required to reduce to 0.1% the survival of clonogens derived from the TMS composed of 100% of NAT gene‐transfected cells were 1.5 and 0.004 MBq/ml (RSV promoter), 8.5 and 0.0075 MBq/ml (hTR promoter), and 9.0 and 0.008 MBq/ml (hTERT promoter), respectively. The concentrations of radiopharmaceutical required to reduce to 0.1% the survival of clonogens derived from 5% RSV/NAT and 5% hTERT/NAT TMS were 14 and 23 MBq/ml, respectively, for treatment with [ 131 I]MIBG and 0.018 and 0.028 MBq/ml, respectively, for treatment with [ 211 At]MABG. Conclusions These results indicate that the telomerase promoters have the capacity to drive the expression of the NAT. The potency of [ 211 At]MABG is approximately three orders of magnitude greater than that of [ 131 I]MIBG. Spheroids composed of only 5% of cells expressing NAT under the control of the RSV or hTERT promoter were sterilised by radiopharmaceutical treatment. This observation is indicative of bystander cell‐kill. Copyright © 2004 John Wiley & Sons, Ltd.