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111In-BnDTPA-F3: an Auger electron-emitting radiotherapeutic agent that targets nucleolin.

Cornelissen B, Waller A, Target C, Kersemans V, Smart S, Vallis KA - EJNMMI Res (2012)

Bottom Line: Of the bound 111In, 15% was internalized, and of this, 37% was localized in the nucleus.Exposure of 231-H2N cells to 111In-BnDTPA-F3 (1 μM, 6 MBq/μg) resulted in a dose-dependent increase in γH2AX foci and in a significant reduction of clonogenic survival compared to untreated cells or cells exposed to unlabeled BnDTPA-F3 (46 ± 4.1%, 100 ± 1.8%, and 132 ± 7.7%, respectively).In tumor growth delay studies, tumor growth rate was reduced 19-fold compared to untreated or unlabeled BnDTPA-F3-treated mice (p = 0.023). 111In-BnDTPA-F3 is internalized into 231-H2N cells and translocates to the nucleus. 111In-BnDTPA-F3 has a potent cytotoxic effect in vitro and an anti-tumor effect in mice bearing 231-H2N xenografts despite modest total tumor accumulation.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Oncology, Cancer Research UK/Medical Research Council Gray Institute for Radiation Oncology and Biology, University of Oxford, Old Road Campus Research Building, Off Roosevelt Drive, Oxford, OX3 7DQ, UK. bart.cornelissen@oncology.ox.ac.uk.

ABSTRACT

Introduction: The F3 peptide (KDEPQRRSARLSAKPAPPKPEPKPKKAPAKK), a fragment of the human high mobility group protein 2, binds nucleolin. Nucleolin is expressed in the nuclei of normal cells but is also expressed on the membrane of some cancer cells. The goal was to investigate the use of 111In-labeled F3 peptide for Auger electron-targeted radiotherapy.

Methods: F3 was labeled with fluorescein isothiocyanate (FITC) for confocal microscopy and conjugated to p-SCN-benzyl-diethylenetriaminepentaacetic acid (BnDTPA) for labeling with 111In to form 111In-BnDTPA-F3. MDA-MB-231-H2N (231-H2N) human breast cancer cells were exposed to 111In-BnDTPA-F3 and used in cell fractionation, γH2AX immunostaining (a marker of DNA double-strand breaks), and clonogenic assays. In vivo, biodistribution studies of 111In-BnDTPA-F3 were performed in 231-H2N xenograft-bearing mice. In tumor growth delay studies, 111In-BnDTPA-F3 (3 μg, 6 MBq/μg) was administered intravenously to 231-H2N xenograft-bearing mice once weekly for 3 weeks.

Results: Membrane-binding of FITC-F3 was observed in 231-H2N cells, and there was co-localization of FITC-F3 with nucleolin in the nuclei. After exposure of 231-H2N cells to 111In-BnDTPA-F3 for 2 h, 1.7% of 111In added to the medium was membrane-bound. Of the bound 111In, 15% was internalized, and of this, 37% was localized in the nucleus. Exposure of 231-H2N cells to 111In-BnDTPA-F3 (1 μM, 6 MBq/μg) resulted in a dose-dependent increase in γH2AX foci and in a significant reduction of clonogenic survival compared to untreated cells or cells exposed to unlabeled BnDTPA-F3 (46 ± 4.1%, 100 ± 1.8%, and 132 ± 7.7%, respectively). In vivo, tumor uptake of 111In-BnDTPA-F3 (3 μg, 6 MBq/μg) at 3-h post-injection was 1% of the injected dose per gram (%ID/g), and muscle uptake was 0.5%ID/g. In tumor growth delay studies, tumor growth rate was reduced 19-fold compared to untreated or unlabeled BnDTPA-F3-treated mice (p = 0.023).

Conclusion: 111In-BnDTPA-F3 is internalized into 231-H2N cells and translocates to the nucleus. 111In-BnDTPA-F3 has a potent cytotoxic effect in vitro and an anti-tumor effect in mice bearing 231-H2N xenografts despite modest total tumor accumulation.

No MeSH data available.


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In vivo biodistribution of 111In-BnDTPA-F3. (A) Representative SPECT image of the distribution of 111In-BnDTPA-F3 in 231-H2N xenograft-bearing mice, 3-h post-intravenous injection. G, gall bladder; K, kidneys; S, spleen; B, bladder. (B) Biodistribution of 111In-BnDTPA-F3, 3-h post-intravenous injection. Results are expressed as the average percentage of the injected dose per gram (%ID/g) of tissue ± SD of the three mice.
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Figure 5: In vivo biodistribution of 111In-BnDTPA-F3. (A) Representative SPECT image of the distribution of 111In-BnDTPA-F3 in 231-H2N xenograft-bearing mice, 3-h post-intravenous injection. G, gall bladder; K, kidneys; S, spleen; B, bladder. (B) Biodistribution of 111In-BnDTPA-F3, 3-h post-intravenous injection. Results are expressed as the average percentage of the injected dose per gram (%ID/g) of tissue ± SD of the three mice.

Mentions: A representative SPECT maximum intensity projection, 3 h after intravenous injection of 3 μg of 111In-BnDTPA-F3 (6 MBq/μg), is shown in Figure 5A. The biodistribution of 111In-BnDTPA-F3 was determined 3 h after i.v. injection of 3 μg (6 MBq/μg). The results are summarized in Figure 5B. 111In-BnDTPA-F3 was mainly taken up in the kidneys (7.0 ± 1.6%ID/g). 111In-BnDTPA-F3 concentration in the blood was relatively high for a peptide of this size (3.2 ± 1.6%ID/g). Tumor uptake was modest (0.80 ± 0.28%ID/g).


111In-BnDTPA-F3: an Auger electron-emitting radiotherapeutic agent that targets nucleolin.

Cornelissen B, Waller A, Target C, Kersemans V, Smart S, Vallis KA - EJNMMI Res (2012)

In vivo biodistribution of 111In-BnDTPA-F3. (A) Representative SPECT image of the distribution of 111In-BnDTPA-F3 in 231-H2N xenograft-bearing mice, 3-h post-intravenous injection. G, gall bladder; K, kidneys; S, spleen; B, bladder. (B) Biodistribution of 111In-BnDTPA-F3, 3-h post-intravenous injection. Results are expressed as the average percentage of the injected dose per gram (%ID/g) of tissue ± SD of the three mice.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3298710&req=5

Figure 5: In vivo biodistribution of 111In-BnDTPA-F3. (A) Representative SPECT image of the distribution of 111In-BnDTPA-F3 in 231-H2N xenograft-bearing mice, 3-h post-intravenous injection. G, gall bladder; K, kidneys; S, spleen; B, bladder. (B) Biodistribution of 111In-BnDTPA-F3, 3-h post-intravenous injection. Results are expressed as the average percentage of the injected dose per gram (%ID/g) of tissue ± SD of the three mice.
Mentions: A representative SPECT maximum intensity projection, 3 h after intravenous injection of 3 μg of 111In-BnDTPA-F3 (6 MBq/μg), is shown in Figure 5A. The biodistribution of 111In-BnDTPA-F3 was determined 3 h after i.v. injection of 3 μg (6 MBq/μg). The results are summarized in Figure 5B. 111In-BnDTPA-F3 was mainly taken up in the kidneys (7.0 ± 1.6%ID/g). 111In-BnDTPA-F3 concentration in the blood was relatively high for a peptide of this size (3.2 ± 1.6%ID/g). Tumor uptake was modest (0.80 ± 0.28%ID/g).

Bottom Line: Of the bound 111In, 15% was internalized, and of this, 37% was localized in the nucleus.Exposure of 231-H2N cells to 111In-BnDTPA-F3 (1 μM, 6 MBq/μg) resulted in a dose-dependent increase in γH2AX foci and in a significant reduction of clonogenic survival compared to untreated cells or cells exposed to unlabeled BnDTPA-F3 (46 ± 4.1%, 100 ± 1.8%, and 132 ± 7.7%, respectively).In tumor growth delay studies, tumor growth rate was reduced 19-fold compared to untreated or unlabeled BnDTPA-F3-treated mice (p = 0.023). 111In-BnDTPA-F3 is internalized into 231-H2N cells and translocates to the nucleus. 111In-BnDTPA-F3 has a potent cytotoxic effect in vitro and an anti-tumor effect in mice bearing 231-H2N xenografts despite modest total tumor accumulation.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Oncology, Cancer Research UK/Medical Research Council Gray Institute for Radiation Oncology and Biology, University of Oxford, Old Road Campus Research Building, Off Roosevelt Drive, Oxford, OX3 7DQ, UK. bart.cornelissen@oncology.ox.ac.uk.

ABSTRACT

Introduction: The F3 peptide (KDEPQRRSARLSAKPAPPKPEPKPKKAPAKK), a fragment of the human high mobility group protein 2, binds nucleolin. Nucleolin is expressed in the nuclei of normal cells but is also expressed on the membrane of some cancer cells. The goal was to investigate the use of 111In-labeled F3 peptide for Auger electron-targeted radiotherapy.

Methods: F3 was labeled with fluorescein isothiocyanate (FITC) for confocal microscopy and conjugated to p-SCN-benzyl-diethylenetriaminepentaacetic acid (BnDTPA) for labeling with 111In to form 111In-BnDTPA-F3. MDA-MB-231-H2N (231-H2N) human breast cancer cells were exposed to 111In-BnDTPA-F3 and used in cell fractionation, γH2AX immunostaining (a marker of DNA double-strand breaks), and clonogenic assays. In vivo, biodistribution studies of 111In-BnDTPA-F3 were performed in 231-H2N xenograft-bearing mice. In tumor growth delay studies, 111In-BnDTPA-F3 (3 μg, 6 MBq/μg) was administered intravenously to 231-H2N xenograft-bearing mice once weekly for 3 weeks.

Results: Membrane-binding of FITC-F3 was observed in 231-H2N cells, and there was co-localization of FITC-F3 with nucleolin in the nuclei. After exposure of 231-H2N cells to 111In-BnDTPA-F3 for 2 h, 1.7% of 111In added to the medium was membrane-bound. Of the bound 111In, 15% was internalized, and of this, 37% was localized in the nucleus. Exposure of 231-H2N cells to 111In-BnDTPA-F3 (1 μM, 6 MBq/μg) resulted in a dose-dependent increase in γH2AX foci and in a significant reduction of clonogenic survival compared to untreated cells or cells exposed to unlabeled BnDTPA-F3 (46 ± 4.1%, 100 ± 1.8%, and 132 ± 7.7%, respectively). In vivo, tumor uptake of 111In-BnDTPA-F3 (3 μg, 6 MBq/μg) at 3-h post-injection was 1% of the injected dose per gram (%ID/g), and muscle uptake was 0.5%ID/g. In tumor growth delay studies, tumor growth rate was reduced 19-fold compared to untreated or unlabeled BnDTPA-F3-treated mice (p = 0.023).

Conclusion: 111In-BnDTPA-F3 is internalized into 231-H2N cells and translocates to the nucleus. 111In-BnDTPA-F3 has a potent cytotoxic effect in vitro and an anti-tumor effect in mice bearing 231-H2N xenografts despite modest total tumor accumulation.

No MeSH data available.


Related in: MedlinePlus