| 1. |
- Nordberg, Erika, et al.
(författare)
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Cellular studies of binding, internalization and retention of a radiolabeled EGFR-binding affibody molecule
- 2007
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Ingår i: Nuclear Medicine and Biology. - : Elsevier BV. - 0969-8051 .- 1872-9614. ; 34:6, s. 609-618
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Tidskriftsartikel (refereegranskat)abstract
- INTRODUCTION: The cellular binding and processing of an epidermal growth factor receptor (EGFR) targeting affibody molecule, (Z(EGFR:955))(2), was studied. This new and small molecule is aimed for applications in nuclear medicine. The natural ligand epidermal growth factor (EGF) and the antibody cetuximab were studied for comparison. METHODS: All experiments were made with cultured A431 squamous carcinoma cells. Receptor specificity, binding time patterns, retention and preliminary receptor binding site localization studies were all made after (125)I labeling. Internalization was studied using Oregon Green 488, Alexa Fluor 488 and CypHer5E markers. RESULTS: [(125)I](Z(EGFR:955))(2) and [(125)I]cetuximab gave a maximum cellular uptake of (125)I within 4 to 8 h of incubation, while [(125)I]EGF gave a maximum uptake already after 2 h. The retention studies showed that the cell-associated fraction of (125)I after 48 h of incubation was approximately 20% when delivered as [(125)I](Z(EGFR:955))(2) and approximately 25% when delivered as [(125)I]cetuximab. [(125)I]EGF-mediated delivery gave a faster (125)I release, where almost all cell-associated radioactivity had disappeared within 24 h. All three substances were internalized as demonstrated with confocal microscopy. Competitive binding studies showed that both EGF and cetuximab inhibited binding of (Z(EGFR:955))(2) and indicated that the three substances competed for an overlapping binding site. CONCLUSION: The results gave information on cellular processing of radionuclides when delivered with (Z(EGFR:955))(2) in comparison to delivery with EGF and cetuximab. Competition assays suggested that [(125)I](Z(EGFR:955))(2) bind to Domain III of EGFR. The affibody molecule (Z(EGFR:955))(2) can be a candidate for EGFR imaging applications in nuclear medicine.
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| 2. |
- Nordberg, Erika, et al.
(författare)
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Cellular uptake of radioiodine delivered by trastuzumab can be modified by the addition of epidermal growth factor.
- 2005
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Ingår i: European Journal of Nuclear Medicine and Molecular Imaging. - : Springer Science and Business Media LLC. - 1619-7070 .- 1619-7089. ; 32:7, s. 771-7
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Tidskriftsartikel (refereegranskat)abstract
- PURPOSE: The purpose of this study was to analyse whether non-radiolabelled epidermal growth factor (EGF) can modify the cellular uptake of 125I when delivered as [125I]trastuzumab. 125I was used as a marker for the diagnostically and therapeutically more interesting isotopes 123I (SPECT), 124I (PET) and 131I (therapy). METHODS: The cell-associated radioactivity was measured in squamous carcinoma A431 cells following addition of [125I]trastuzumab. Different concentrations of [125I]trastuzumab and unlabelled EGF were used, and the total, membrane-bound and internalised radioactivity was measured. We also analysed how EGF and trastuzumab affected the cell growth. RESULTS: It was generally found that the cellular 125I uptake was decreased by the addition of EGF when [125I]trastuzumab was added for short incubation times. However, if the incubation times were longer, EGF increased the 125I uptake. This shift came earlier when higher [125I]trastuzumab concentrations were applied. The addition of EGF also influenced cell proliferation, and concentrations above 10 ng/ml reduced cell growth by approximately 20% after 24 h of incubation. CONCLUSION: By adding unlabelled EGF, it was possible to modify the cellular uptake of [125I]trastuzumab. This points towards new approaches for the modification of radionuclide uptake in EGFR- and HER2-positive tumours.
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| 3. |
- Nordberg, Erika, 1980-
(författare)
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EGFR and HER2 Targeting for Radionuclide-Based Imaging and Therapy : Preclinical Studies
- 2008
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The optimal way to detect and treat cancer is to target cancer cells exclusively without affecting the surrounding tissue. One promising approach is to use radiolabelled molecules to target receptors that are overexpressed in cancer cells. Since the epidermal growth factor receptor (EGFR) family is overexpressed in many types of cancer, it is an attractive target for both diagnostic and therapeutic applications. This thesis can be divided into two parts. In part one (paper I), studies were conducted to modulate radionuclide uptake in tumour cells. The results showed that it was possible to modulate the cellular uptake of 125I delivered by trastuzumab (targeting HER2) by adding EGF (targeting EGFR). In part two (papers II-V) a high affinity EGFR-targeting affibody molecule (ZEGFR:955)2 was selected and analysed both in vitro and in vivo. In papers II, III and V, the results obtained when using (ZEGFR:955)2 were compared with those obtained with the two EGFR-binding molecules, EGF and cetuximab. These studies demonstrated that the affibody molecule bound specifically to EGFR (probably to subdomain III) with high affinity (~50 nM in biosensor analysis and ~1 nM in cellular studies) and produced intracellular signalling changes similar to those with cetuximab. In paper IV, in vivo studies were made, demonstrating that [111In](ZEGFR:955)2 gave a tumour-specific 111In uptake of 3.8±1.4% of injected dose per gram tumour tissue, 4 h post-injection. The tumours could be easily visualized with a gamma camera at this time-point. The results of these studies indicated that the affibody molecule (ZEGFR:955)2 is a possible candidate for radionuclide-based imaging of EGFR-expressing tumours. The biological effects of (ZEGFR:955)2 might be of interest for therapy applications.
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| 4. |
- Nordberg, Erika, et al.
(författare)
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In vivo and in vitro uptake of In-111, delivered with the affibody molecule(Z(EGFR:955))(2), in EGFR expressing tumour cells
- 2008
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Ingår i: Oncology Reports. - : Spandidos Publications. - 1021-335X .- 1791-2431. ; 19:4, s. 853-857
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Tidskriftsartikel (refereegranskat)abstract
- The epidermal growth factor receptor, EGFR, is overexpressed in many carcinomas. Targeting this receptor with radionuclides is important for imaging and therapy applications in nuclear medicine. We investigated the in vitro and in vivo properties of a new high affinity EGFR binding affibody molecule, (Z(EGFR:955))(2), when conjugated with CHXA"-DTPA and labelled with In-111. The binding time patterns and retention studies were performed using cultured squamous carcinoma A431 cells that overexpress EGFR. In the in vivo studies, female BALB/c nu/nu mice carrying tumours from xenografted A431 cells were used. The in vitro studies showed EGFR specific binding, high uptake and good retention of In-111 when delivered as [In-111](Z(EGFR:955))(2). The retention after 72 h of incubation was 38.0 +/- 1.15% of the initial level. The biodistribution study showed a tumour specific In-111 uptake of 3.8 +/- 1.4% of injected dose per gram turnout tissue 4 h post-injection. The tumour to blood ratio was 9.1 and the tumours could easily be visualized with a gamma camera at this time-point. In-111 delivered with [In-111](Z(EGFR:955))(2) gave an EGFR specific uptake and the results indicated that the (Z(EGFR:955))(2) affibody molecule is a candidate for radionuclide-based tumour imaging. Potential therapy applications are discussed.
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