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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 xenograft growth inhibition by 111In-BnDTPA-F3. Mice, bearing 231-H2N xenografts, were injected intravenously with PBS, BnDTPA-F3, or 111In-BnDTPA-F3. Tumor size was measured twice weekly by a caliper. (A) Normalized tumor volume. (B) Growth rate (K) in mm3 per day. Results are expressed as average growth rates of tumors in seven mice ± SEM. **p = 0.0031. (C) Kaplan-Meier survival curves generated using the time tumors reached twice the size at the beginning of the study (V =2V0). (D) Kaplan-Meier survival curves. Mice were killed when the tumor reached its maximally allowed volume (V =Vmax).
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Figure 6: In vivo xenograft growth inhibition by 111In-BnDTPA-F3. Mice, bearing 231-H2N xenografts, were injected intravenously with PBS, BnDTPA-F3, or 111In-BnDTPA-F3. Tumor size was measured twice weekly by a caliper. (A) Normalized tumor volume. (B) Growth rate (K) in mm3 per day. Results are expressed as average growth rates of tumors in seven mice ± SEM. **p = 0.0031. (C) Kaplan-Meier survival curves generated using the time tumors reached twice the size at the beginning of the study (V =2V0). (D) Kaplan-Meier survival curves. Mice were killed when the tumor reached its maximally allowed volume (V =Vmax).

Mentions: The 231-H2N xenograft tumors in mice that received three weekly doses of 111In-BnDTPA-F3 (3 μg, 6 MBq/μg) grew significantly slower compared with those in mice that received cold, unlabeled BnDTPA-F3 or PBS control (growth rate = 0.0043 ± 0.0061, 0.080 ± 0.019, and 0.082 ± 0.013 mm3/day, respectively; p = 0.0031) (Figure 6A, B). Kaplan-Meier curves showed a significant difference in time for the tumor to grow twice its original volume (p = 0.0073) (Figure 6C) as well as survival time (p = 0.0174) (Figure 6D).


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 xenograft growth inhibition by 111In-BnDTPA-F3. Mice, bearing 231-H2N xenografts, were injected intravenously with PBS, BnDTPA-F3, or 111In-BnDTPA-F3. Tumor size was measured twice weekly by a caliper. (A) Normalized tumor volume. (B) Growth rate (K) in mm3 per day. Results are expressed as average growth rates of tumors in seven mice ± SEM. **p = 0.0031. (C) Kaplan-Meier survival curves generated using the time tumors reached twice the size at the beginning of the study (V =2V0). (D) Kaplan-Meier survival curves. Mice were killed when the tumor reached its maximally allowed volume (V =Vmax).
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 6: In vivo xenograft growth inhibition by 111In-BnDTPA-F3. Mice, bearing 231-H2N xenografts, were injected intravenously with PBS, BnDTPA-F3, or 111In-BnDTPA-F3. Tumor size was measured twice weekly by a caliper. (A) Normalized tumor volume. (B) Growth rate (K) in mm3 per day. Results are expressed as average growth rates of tumors in seven mice ± SEM. **p = 0.0031. (C) Kaplan-Meier survival curves generated using the time tumors reached twice the size at the beginning of the study (V =2V0). (D) Kaplan-Meier survival curves. Mice were killed when the tumor reached its maximally allowed volume (V =Vmax).
Mentions: The 231-H2N xenograft tumors in mice that received three weekly doses of 111In-BnDTPA-F3 (3 μg, 6 MBq/μg) grew significantly slower compared with those in mice that received cold, unlabeled BnDTPA-F3 or PBS control (growth rate = 0.0043 ± 0.0061, 0.080 ± 0.019, and 0.082 ± 0.013 mm3/day, respectively; p = 0.0031) (Figure 6A, B). Kaplan-Meier curves showed a significant difference in time for the tumor to grow twice its original volume (p = 0.0073) (Figure 6C) as well as survival time (p = 0.0174) (Figure 6D).

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