1
|
Spoormans K, Crabbé M, Struelens L, De Saint-Hubert M, Koole M. A Review on Tumor Control Probability (TCP) and Preclinical Dosimetry in Targeted Radionuclide Therapy (TRT). Pharmaceutics 2022; 14:pharmaceutics14102007. [PMID: 36297446 PMCID: PMC9608466 DOI: 10.3390/pharmaceutics14102007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2022] [Revised: 09/12/2022] [Accepted: 09/13/2022] [Indexed: 12/05/2022] Open
Abstract
Targeted radionuclide therapy (TRT) uses radiopharmaceuticals to specifically irradiate tumor cells while sparing healthy tissue. Response to this treatment highly depends on the absorbed dose. Tumor control probability (TCP) models aim to predict the tumor response based on the absorbed dose by taking into account the different characteristics of TRT. For instance, TRT employs radiation with a high linear energy transfer (LET), which results in an increased effectiveness. Furthermore, a heterogeneous radiopharmaceutical distribution could result in a heterogeneous dose distribution at a tissue, cellular as well as subcellular level, which will generally reduce the tumor response. Finally, the dose rate in TRT is protracted, relatively low, and variable over time. This allows cells to repair more DNA damage, which may reduce the effectiveness of TRT. Within this review, an overview is given on how these characteristics can be included in TCP models, while some experimental findings are also discussed. Many parameters in TCP models are preclinically determined and TCP models also play a role in the preclinical stage of radiopharmaceutical development; however, this all depends critically on the calculated absorbed dose. Accordingly, an overview of the existing preclinical dosimetry methods is given, together with their limitation and applications. It can be concluded that although the theoretical extension of TCP models from external beam radiotherapy towards TRT has been established quite well, the experimental confirmation is lacking. Thus, requiring additional comprehensive studies at the sub-cellular, cellular, and organ level, which should be provided with accurate preclinical dosimetry.
Collapse
Affiliation(s)
- Kaat Spoormans
- Research in Dosimetric Applications, Belgian Nuclear Research Center (SCK CEN), 2400 Mol, Belgium
- Unit of Nuclear Medicine and Molecular Imaging, Department of Imaging and Pathology, Katholieke Universiteit Leuven (KUL), 3000 Leuven, Belgium
- Correspondence:
| | - Melissa Crabbé
- NURA Research Group, Belgian Nuclear Research Center (SCK CEN), 2400 Mol, Belgium
| | - Lara Struelens
- Research in Dosimetric Applications, Belgian Nuclear Research Center (SCK CEN), 2400 Mol, Belgium
| | - Marijke De Saint-Hubert
- Research in Dosimetric Applications, Belgian Nuclear Research Center (SCK CEN), 2400 Mol, Belgium
| | - Michel Koole
- Unit of Nuclear Medicine and Molecular Imaging, Department of Imaging and Pathology, Katholieke Universiteit Leuven (KUL), 3000 Leuven, Belgium
| |
Collapse
|
2
|
Bill MA, Srivastava K, Breen C, Butterworth KT, McMahon SJ, Prise KM, McCloskey KD. Dual effects of radiation bystander signaling in urothelial cancer: purinergic-activation of apoptosis attenuates survival of urothelial cancer and normal urothelial cells. Oncotarget 2017; 8:97331-97343. [PMID: 29228614 PMCID: PMC5722566 DOI: 10.18632/oncotarget.21995] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2017] [Accepted: 08/26/2017] [Indexed: 01/29/2023] Open
Abstract
Radiation therapy (RT) delivers tumour kill, directly and often via bystander mechanisms. Bladder toxicity is a dose limiting constraint in pelvic RT, manifested as radiation cystitis and urinary symptoms. We aimed to investigate the impact of radiation-induced bystander signaling on normal/cancer urothelial cells. Human urothelial cancer cells T24, HT1376 and normal urothelial cells HUC, SV-HUC were used. Cells were irradiated and studied directly, or conditioned medium from irradiated cells (CM) was transferred to naïve, cells. T24 or SV-HUC cells in the shielded half of irradiated flasks had increased numbers of DNA damage foci vs non-irradiated cells. A physical barrier blocked this response, indicating release of transmitters from irradiated cells. Clonogenic survival of shielded T24 or SV-HUC was also reduced; a physical barrier prevented this phenomenon. CM-transfer increased pro-apoptotic caspase-3 activity, increased cleaved caspase-3 and cleaved PARP expression and reduced survival protein XIAP expression. This effect was mimicked by ATP. ATP or CM evoked suramin-sensitive Ca2+-signals. Irradiation increased [ATP] in CM from T24. The CM-inhibitory effect on T24 clonogenic survival was blocked by apyrase, or mimicked by ATP. We conclude that radiation-induced bystander signaling enhances urothelial cancer cell killing via activation of purinergic pro-apoptotic pathways. This benefit is accompanied by normal urothelial damage indicating RT bladder toxicity is also bystander-mediated.
Collapse
Affiliation(s)
- Malgorzata A Bill
- Centre for Cancer Research and Cell Biology, School of Medicine, Dentistry and Biomedical Sciences, Queen's University Belfast, Belfast, BT9 7AE, Northern Ireland, UK
| | - Kirtiman Srivastava
- Centre for Cancer Research and Cell Biology, School of Medicine, Dentistry and Biomedical Sciences, Queen's University Belfast, Belfast, BT9 7AE, Northern Ireland, UK
| | - Conor Breen
- Centre for Cancer Research and Cell Biology, School of Medicine, Dentistry and Biomedical Sciences, Queen's University Belfast, Belfast, BT9 7AE, Northern Ireland, UK
| | - Karl T Butterworth
- Centre for Cancer Research and Cell Biology, School of Medicine, Dentistry and Biomedical Sciences, Queen's University Belfast, Belfast, BT9 7AE, Northern Ireland, UK
| | - Stephen J McMahon
- Centre for Cancer Research and Cell Biology, School of Medicine, Dentistry and Biomedical Sciences, Queen's University Belfast, Belfast, BT9 7AE, Northern Ireland, UK
| | - Kevin M Prise
- Centre for Cancer Research and Cell Biology, School of Medicine, Dentistry and Biomedical Sciences, Queen's University Belfast, Belfast, BT9 7AE, Northern Ireland, UK
| | - Karen D McCloskey
- Centre for Cancer Research and Cell Biology, School of Medicine, Dentistry and Biomedical Sciences, Queen's University Belfast, Belfast, BT9 7AE, Northern Ireland, UK
| |
Collapse
|
3
|
Zhao Y, Zhong X, Ou X, Cai H, Wu X, Huang R. Cotransfecting norepinephrine transporter and vesicular monoamine transporter 2 genes for increased retention of metaiodobenzylguanidine labeled with iodine 131 in malignant hepatocarcinoma cells. Front Med 2017; 11:120-128. [PMID: 28213878 DOI: 10.1007/s11684-017-0501-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2016] [Accepted: 11/24/2016] [Indexed: 02/05/2023]
Abstract
Norepinephrine transporter (NET) transfection leads to significant uptake of iodine-131-labeled metaiodobenzylguanidine (131I-MIBG) in non-neuroendocrine tumors. However, the use of 131I-MIBG is limited by its short retention time in target cells. To prolong the retention of 131I-MIBG in target cells, we infected hepatocarcinoma (HepG2) cells with Lentivirus-encoding human NET and vesicular monoamine transporter 2 (VMAT2) genes to obtain NET-expressing, NET-VMAT2-coexpressing, and negative-control cell lines. We evaluated the uptake and efflux of 131I-MIBG both in vitro and in vivo in mice bearing transfected tumors. NET-expressing and NET-VMAT2-coexpressing cells respectively showed 2.24 and 2.22 times higher 131I-MIBG uptake than controls. Two hours after removal of 131I-MIBG-containing medium, 25.4% efflux was observed in NET-VMAT2-coexpressing cells and 38.6% in NET-expressing cells. In vivo experiments were performed in nude mice bearing transfected tumors; results revealed that NET-VMAT2-coexpressing tumors had longer 131I-MIBG retention time than NET-expressing tumors. Meanwhile, NET-VMAT2-coexpressing and NET-expressing tumors displayed 0.54% and 0.19%, respectively, of the injected dose per gram of tissue 24 h after 131I-MIBG administration. Cotransfection of HepG2 cells with NET and VMAT2 resulted in increased 131I-MIBG uptake and retention. However, the degree of increase was insufficient to be therapeutically effective in target cells.
Collapse
Affiliation(s)
- Yanlin Zhao
- Department of Nuclear Medicine, West China Hospital, Sichuan University, Chengdu, 610041, China
| | - Xiao Zhong
- Department of Nuclear Medicine, West China Hospital, Sichuan University, Chengdu, 610041, China
| | - Xiaohong Ou
- Department of Nuclear Medicine, West China Hospital, Sichuan University, Chengdu, 610041, China.
| | - Huawei Cai
- Department of Nuclear Medicine, West China Hospital, Sichuan University, Chengdu, 610041, China
| | - Xiaoai Wu
- Department of Nuclear Medicine, West China Hospital, Sichuan University, Chengdu, 610041, China
| | - Rui Huang
- Department of Nuclear Medicine, West China Hospital, Sichuan University, Chengdu, 610041, China
| |
Collapse
|
4
|
Gow MD, Seymour CB, Boyd M, Mairs RJ, Prestiwch WV, Mothersill CE. Dose calculations for [(131)i] meta-iodobenzylguanidine-induced bystander effects. Dose Response 2013; 12:1-23. [PMID: 24659931 DOI: 10.2203/dose-response.13-001.mothersill] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
UNLABELLED Targeted radiotherapy is a potentially useful treatment for some cancers and may be potentiated by bystander effects. However, without estimation of absorbed dose, it is difficult to compare the effects with conventional external radiation treatment. METHODS Using the Vynckier - Wambersie dose point kernel, a model for dose rate evaluation was created allowing for calculation of absorbed dose values to two cell lines transfected with the noradrenaline transporter (NAT) gene and treated with [(131)I]MIBG. RESULTS The mean doses required to decrease surviving fractions of UVW/NAT and EJ138/NAT cells, which received medium from [(131)I]MIBG-treated cells, to 25 - 30% were 1.6 and 1.7 Gy respectively. The maximum mean dose rates achieved during [(131)I]MIBG treatment were 0.09 - 0.75 Gy/h for UVW/NAT and 0.07 - 0.78 Gy/h for EJ138/NAT. These were significantly lower than the external beam gamma radiation dose rate of 15 Gy/h. In the case of control lines which were incapable of [(131)I]MIBG uptake the mean absorbed doses following radiopharmaceutical were 0.03 - 0.23 Gy for UVW and 0.03 - 0.32 Gy for EJ138. CONCLUSION [(131)I]MIBG treatment for ICCM production elicited a bystander dose-response profile similar to that generated by external beam gamma irradiation but with significantly greater cell death.
Collapse
Affiliation(s)
- M D Gow
- Medical Physics and Applied Radiation Sciences Department, McMaster University, Hamilton, Ontario, Canada L8S 4K1
| | - C B Seymour
- Medical Physics and Applied Radiation Sciences Department, McMaster University, Hamilton, Ontario, Canada L8S 4K1
| | - M Boyd
- Targeted Therapy Group, Division of Cancer Science and Molecular Pathology, Glasgow University, Cancer Research United Kingdom Beatson Laboratories, Glasgow, United Kingdom
| | - R J Mairs
- Targeted Therapy Group, Division of Cancer Science and Molecular Pathology, Glasgow University, Cancer Research United Kingdom Beatson Laboratories, Glasgow, United Kingdom; ; Department of Child Health, Yorkhill Hospital, Glasgow, United Kingdom
| | - W V Prestiwch
- Medical Physics and Applied Radiation Sciences Department, McMaster University, Hamilton, Ontario, Canada L8S 4K1
| | - C E Mothersill
- Medical Physics and Applied Radiation Sciences Department, McMaster University, Hamilton, Ontario, Canada L8S 4K1
| |
Collapse
|
5
|
McCluskey AG, Mairs RJ, Sorensen A, Robson T, McCarthy HO, Pimlott SL, Babich JW, Champion S, Boyd M. Gamma irradiation and targeted radionuclides enhance the expression of the noradrenaline transporter transgene controlled by the radio-inducible p21(WAF1/CIP1) promoter. Radiat Res 2013; 179:282-92. [PMID: 23336184 DOI: 10.1667/rr3030.1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
The use of radiation-inducible promoters to drive transgene expression offers the possibility of temporal and spatial regulation of gene activation. This study assessed the potential of one such promoter element, p21(WAF1/CIP1) (WAF1), to drive expression of the noradrenaline transporter (NAT) gene, which conveys sensitivity to radioiodinated meta-iodobenzylguanidine (MIBG). An expression vector containing NAT under the control of the radiation-inducible WAF1 promoter (pWAF/NAT) was produced. The non-NAT expressing cell lines UVW (glioma) and HCT116 (colorectal cancer) were transfected with this construct to assess radiation-controlled WAF1 activation of the NAT gene. Transfection of UVW and HCT cells with pWAF/NAT conferred upon them the ability to accumulate [(131)I]MIBG, which led to increased sensitivity to the radiopharmaceutical. Pretreatment of transfected cells with γ radiation or the radiopharmaceuticals [(123)I]MIBG or [(131)I]MIBG induced dose- and time-dependent increases in subsequent [(131)I]MIBG uptake and led to enhanced efficacy of [(131)I]MIBG-mediated cell kill. Gene therapy using WAF1-driven expression of NAT has the potential to expand the use of this therapeutic modality to tumors that lack a radio-targetable feature.
Collapse
Affiliation(s)
- Anthony G McCluskey
- Experimental Targeted Radiation Therapeutics Group, Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, Glasgow, United Kingdom.
| | | | | | | | | | | | | | | | | |
Collapse
|
6
|
Evaluation of Norepinephrine Transporter Expression and Metaiodobenzylguanidine Avidity in Neuroblastoma: A Report from the Children's Oncology Group. INTERNATIONAL JOURNAL OF MOLECULAR IMAGING 2012; 2012:250834. [PMID: 23050139 PMCID: PMC3463166 DOI: 10.1155/2012/250834] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/03/2012] [Accepted: 08/23/2012] [Indexed: 11/18/2022]
Abstract
Purpose. (123)I-metaiodobenzylguanidine (MIBG) is used for the diagnostic evaluation of neuroblastoma. We evaluated the relationship between norepinephrine transporter (NET) expression and clinical MIBG uptake. Methods. Quantitative reverse transcription PCR (N = 82) and immunohistochemistry (IHC; N = 61) were performed for neuroblastoma NET mRNA and protein expression and correlated with MIBG avidity on diagnostic scans. The correlation of NET expression with clinical features was also performed. Results. Median NET mRNA expression level for the 19 MIBG avid patients was 12.9% (range 1.6-73.7%) versus 5.9% (range 0.6-110.0%) for the 8 nonavid patients (P = 0.31). Median percent NET protein expression was 50% (range 0-100%) in MIBG avid patients compared to 10% (range 0-80%) in nonavid patients (P = 0.027). MYCN amplified tumors had lower NET protein expression compared to nonamplified tumors (10% versus 50%; P = 0.0002). Conclusions. NET protein expression in neuroblastoma correlates with MIBG avidity. MYCN amplified tumors have lower NET protein expression.
Collapse
|
7
|
Kumar HR, Zhong X, Hoelz DJ, Rescorla FJ, Hickey RJ, Malkas LH, Sandoval JA. Three-dimensional neuroblastoma cell culture: proteomic analysis between monolayer and multicellular tumor spheroids. Pediatr Surg Int 2008; 24:1229-34. [PMID: 18797883 PMCID: PMC2804865 DOI: 10.1007/s00383-008-2245-2] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 08/15/2008] [Indexed: 11/29/2022]
Abstract
INTRODUCTION Solid tumors, such as neuroblastoma (NB), are associated with a heterogeneous cell environment. Multicellular tumor spheroid (MCTS) cultures have been shown to better mimic growth characteristics of in vivo solid tumors. Because tumor spheroid growth patterns may be quite different from standard two-dimensional culture systems, we sought to compare the protein expression profiles of two- and three-dimensional in vitro NB cultures, i.e., monolayers and MCTS. MATERIALS AND METHODS Human NB cells were grown as both monolayers and spheres. Nuclear and cytosolic proteins were analyzed for differentially secreted proteins by two-dimensional polyacrylamide gel electrophoresis (2-D PAGE) and selected polypeptides were identified by mass spectrometry (LC-MS/MS). RESULTS Several metabolic (transketolase, triosephosphate isomerase, pyruvate kinase M1/M2, alpha enolase, and phosphoglycerate mutase-1), cell stress response (heat shock proteins (HSP) 90, 70, and 60; antioxidant, thioredoxin), cell structure (septin 2, adenyl cyclase-associated protein-1), tubulin beta-2 chain, actin, translationally controlled tumor protein and cofilin), signal transduction (peptidyl prolyl cis/trans isomerase A), biosynthetic (phosphoserine aminotransferase) and transport (cellular retinoic acid binding protein 1) polypeptides were overexpressed in spheroids. Several protein groups were differentially expressed between NB monolayers and spheroids. CONCLUSION The altered proteins among NB spheroids may represent an important link between monolayer cell cultures and in vivo experiments and thus a more ideal in vitro culture system for determining the precise three-dimensional microenvironment of NB.
Collapse
Affiliation(s)
- Hari R. Kumar
- Section of Pediatric Surgery, Indiana University School of Medicine and Riley Children’s Hospital, 545 N. Barnhill, Dr. EH202, Indianapolis, IN 46202, USA
| | - Xiaoling Zhong
- Section of Pediatric Surgery, Indiana University School of Medicine and Riley Children’s Hospital, 545 N. Barnhill, Dr. EH202, Indianapolis, IN 46202, USA
| | - Derek J. Hoelz
- Division of Hematology/Oncology, Indiana University School of Medicine and Riley Children’s Hospital, 545 N. Barnhill, Dr. EH202, Indianapolis, IN 46202, USA
| | - Frederick J. Rescorla
- Section of Pediatric Surgery, Indiana University School of Medicine and Riley Children’s Hospital, 545 N. Barnhill, Dr. EH202, Indianapolis, IN 46202, USA
- Department of Surgery, Indiana University School of Medicine and Riley Children’s Hospital, 545 N. Barnhill Dr. EH202, Indianapolis, IN 46202, USA, e-mail:
| | - Robert J. Hickey
- Division of Hematology/Oncology, Indiana University School of Medicine and Riley Children’s Hospital, 545 N. Barnhill, Dr. EH202, Indianapolis, IN 46202, USA
| | - Linda H. Malkas
- Division of Hematology/Oncology, Indiana University School of Medicine and Riley Children’s Hospital, 545 N. Barnhill, Dr. EH202, Indianapolis, IN 46202, USA
| | - John A. Sandoval
- Department of Surgery, Indiana University School of Medicine and Riley Children’s Hospital, 545 N. Barnhill Dr. EH202, Indianapolis, IN 46202, USA, e-mail:
| |
Collapse
|
8
|
Abstract
The norepinephrine transporter (NET) terminates noradrenergic signalling by rapid re-uptake of neuronally released norepinephrine (NE) into presynaptic terminals. NET exerts a fine regulated control over NE-mediated behavioural and physiological effects including mood, depression, feeding behaviour, cognition, regulation of blood pressure and heart rate. NET is a target of several drugs which are therapeutically used in the treatment or diagnosis of disorders among which depression, attention-deficit hyperactivity disorder and feeding disturbances are the most common. Individual genetic variations in the gene encoding the human NET (hNET), located at chromosome 16q12.2, may contribute to the pathogenesis of those diseases. An increasing number of studies concerning the identification of single nucleotide polymorphisms in the hNET gene and their potential association with disease as well as the functional investigation of naturally occurring or induced amino acid variations in hNET have contributed to a better understanding of NET function, regulation and genetic contribution to disorders. This review will reflect the current knowledge in the field of NET from its initial discovery until now.
Collapse
Affiliation(s)
- H Bönisch
- Department of Pharmacology and Toxicology, University of Bonn, Reuterstr. 2b, 53115 Bonn, Germany.
| | | |
Collapse
|
9
|
Mairs RJ, Fullerton NE, Cosimo E, Boyd M. Gene manipulation to enhance MIBG-targeted radionuclide therapy. Nucl Med Biol 2006; 32:749-53. [PMID: 16243651 DOI: 10.1016/j.nucmedbio.2005.03.011] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2005] [Revised: 03/22/2005] [Accepted: 03/24/2005] [Indexed: 11/18/2022]
Abstract
The goal of targeted radionuclide therapy is the deposition in malignant cells of sterilizing doses of radiation without damaging normal tissue. The radiopharmaceutical [(131)I]meta-iodobenzylguanidine ([(131)I]MIBG) is an effective single agent for the treatment of neuroblastoma. However, uptake of the drug in malignant sites is insufficient to cure disease. A growing body of experimental evidence indicates exciting possibilities for the integration of gene transfer with [(131)I]MIBG-targeted radiotherapy.
Collapse
Affiliation(s)
- Robert J Mairs
- Targeted Therapy Group, Centre for Oncology and Applied Pharmacology, Cancer Research UK Beatson Laboratories, University of Glasgow.
| | | | | | | |
Collapse
|
10
|
Bilsland AE, Fletcher-Monaghan A, Keith WN. Properties of a telomerase-specific Cre/Lox switch for transcriptionally targeted cancer gene therapy. Neoplasia 2006; 7:1020-9. [PMID: 16331888 PMCID: PMC1502022 DOI: 10.1593/neo.05385] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2005] [Revised: 08/02/2005] [Accepted: 08/03/2005] [Indexed: 11/18/2022]
Abstract
Telomerase expression represents a good target for cancer gene therapy. The promoters of the core telomerase catalytic [human telomerase reverse transcriptase (hTERT)] and RNA [human telomerase RNA (hTR)] subunits show selective activity in cancer cells but not in normal cells. This property can be harnessed to express therapeutic transgenes in a wide range of cancer cells. Unfortunately, weak hTR and hTERT promoter activities in some cancer cells could limit the target cell range. Therefore, strategies to enhance telomerase-specific gene therapy are of interest. We constructed a Cre/Lox reporter switch coupling telomerase promoter specificity with Cytomegalovirus (CMV) promoter activity, which is generally considered to be constitutively high. In this approach, a telomerase-specific vector expressing Cre recombinase directs excisive recombination on a second vector, removing a transcriptional blockade to CMV-dependent luciferase expression. We tested switch activation in cell lines over a wide range of telomerase promoter activities. However, Cre/Lox-dependent luciferase expression was not enhanced relative to expression using hTR or hTERT promoters directly. Cell-specific differences between telomerase and CMV promoter activities and incomplete sigmoid switch activation were limiting factors. Notably, CMV activity was not always significantly stronger than telomerase promoter activity. Our conclusions provide a general basis for a more rational design of novel recombinase switches in gene therapy.
Collapse
Affiliation(s)
- Alan E Bilsland
- Cancer Research UK Centre for Oncology and Applied Pharmacology, University of Glasgow, Cancer Research UK Beatson Laboratories, Garscube Estate, Switchback Road, UK
| | | | | |
Collapse
|