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Synthesis and investigation of a radioiodinated F3 peptide analog as a SPECT tumor imaging radioligand.

Bhojani MS, Ranga R, Luker GD, Rehemtulla A, Ross BD, Van Dort ME - PLoS ONE (2011)

Bottom Line: For this purpose, we custom synthesized a modified F3 peptide analog (F3Cys) incorporating a C-terminal cysteine residue for site-specific attachment of a radioiodinated maleimide conjugating group.These results were also confirmed by ex vivo tissue analysis.No-carrier-added [(125)I]IBMF3 was synthesized by a radioiododestannylation approach in 73% overall radiochemical yield.

View Article: PubMed Central - PubMed

Affiliation: Department of Radiation Oncology, University of Michigan, Ann Arbor, Michigan, United States of America.

ABSTRACT
A radioiodinated derivative of the tumor-homing F3 peptide, (N-(2-{3-[(125)I]Iodobenzoyl}aminoethyl)maleimide-F3Cys peptide, [(125)I]IBMF3 was developed for investigation as a SPECT tumor imaging radioligand. For this purpose, we custom synthesized a modified F3 peptide analog (F3Cys) incorporating a C-terminal cysteine residue for site-specific attachment of a radioiodinated maleimide conjugating group. Initial proof-of-concept Fluorescence studies conducted with AlexaFluor 532 C(5) maleimide-labeled F3Cys showed distinct membrane and nuclear localization of F3Cys in MDA-MB-435 cells. Additionally, F3Cys conjugated with NIR fluorochrome AlexaFluor 647 C(2) maleimide demonstrated high tumor specific uptake in melanoma cancer MDA-MB-435 and lung cancer A549 xenografts in nude mice whereas a similarly labeled control peptide did not show any tumor uptake. These results were also confirmed by ex vivo tissue analysis. No-carrier-added [(125)I]IBMF3 was synthesized by a radioiododestannylation approach in 73% overall radiochemical yield. In vitro cell uptake studies conducted with [(125)I]IBMF3 displayed a 5-fold increase in its cell uptake at 4 h when compared to controls. SPECT imaging studies with [(125)I]IBMF3 in tumor bearing nude mice showed clear visualization of MDA-MB-435 xenografts on systemic administration. These studies demonstrate a potential utility of F3 peptide-based radioligands for tumor imaging with PET or SPECT techniques.

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In vitro cell uptake and in vivo SPECT imaging with [125I]IBMF3.(A) MDA-MB-435 cells were incubated with [125I]IBMF3 either alone or in the presence of F3Cys for 0 h or 4 h and uptake of [125I]IBMF3 was measured. To determine non-specific binding cells in control group were treated with [125I]IBMF3, the media removed immediately after addition of the radioligand and processed as for the experimental group. All experiments were performed in triplicate and repeated at least thrice. The data presented here is an average of radioactivity counts per well +/− SD. (B) Mice bearing MDA-MB-435 xenografts were injected i.v. via the tail vein with [125I]IBMF3 and animals were serially imaged post injection. Representative images obtained at 15 min and 4 h post-injection are shown.
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pone-0022418-g004: In vitro cell uptake and in vivo SPECT imaging with [125I]IBMF3.(A) MDA-MB-435 cells were incubated with [125I]IBMF3 either alone or in the presence of F3Cys for 0 h or 4 h and uptake of [125I]IBMF3 was measured. To determine non-specific binding cells in control group were treated with [125I]IBMF3, the media removed immediately after addition of the radioligand and processed as for the experimental group. All experiments were performed in triplicate and repeated at least thrice. The data presented here is an average of radioactivity counts per well +/− SD. (B) Mice bearing MDA-MB-435 xenografts were injected i.v. via the tail vein with [125I]IBMF3 and animals were serially imaged post injection. Representative images obtained at 15 min and 4 h post-injection are shown.

Mentions: The cellular uptake of [125I]IBMF3 was determined by incubating MDA-MB-435 cells with [125I]IBMF3 for 4 h in presence or absence of F3Cys. An almost 5-fold increase in [125I]IBMF3 uptake was observed at 4 h when compared to controls (Figure 4A). Further, competition with unlabeled F3Cys peptide reduced the uptake of [125I]IBMF3 to levels seen in controls, confirming the specificity of its cell uptake.


Synthesis and investigation of a radioiodinated F3 peptide analog as a SPECT tumor imaging radioligand.

Bhojani MS, Ranga R, Luker GD, Rehemtulla A, Ross BD, Van Dort ME - PLoS ONE (2011)

In vitro cell uptake and in vivo SPECT imaging with [125I]IBMF3.(A) MDA-MB-435 cells were incubated with [125I]IBMF3 either alone or in the presence of F3Cys for 0 h or 4 h and uptake of [125I]IBMF3 was measured. To determine non-specific binding cells in control group were treated with [125I]IBMF3, the media removed immediately after addition of the radioligand and processed as for the experimental group. All experiments were performed in triplicate and repeated at least thrice. The data presented here is an average of radioactivity counts per well +/− SD. (B) Mice bearing MDA-MB-435 xenografts were injected i.v. via the tail vein with [125I]IBMF3 and animals were serially imaged post injection. Representative images obtained at 15 min and 4 h post-injection are shown.
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Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3139646&req=5

pone-0022418-g004: In vitro cell uptake and in vivo SPECT imaging with [125I]IBMF3.(A) MDA-MB-435 cells were incubated with [125I]IBMF3 either alone or in the presence of F3Cys for 0 h or 4 h and uptake of [125I]IBMF3 was measured. To determine non-specific binding cells in control group were treated with [125I]IBMF3, the media removed immediately after addition of the radioligand and processed as for the experimental group. All experiments were performed in triplicate and repeated at least thrice. The data presented here is an average of radioactivity counts per well +/− SD. (B) Mice bearing MDA-MB-435 xenografts were injected i.v. via the tail vein with [125I]IBMF3 and animals were serially imaged post injection. Representative images obtained at 15 min and 4 h post-injection are shown.
Mentions: The cellular uptake of [125I]IBMF3 was determined by incubating MDA-MB-435 cells with [125I]IBMF3 for 4 h in presence or absence of F3Cys. An almost 5-fold increase in [125I]IBMF3 uptake was observed at 4 h when compared to controls (Figure 4A). Further, competition with unlabeled F3Cys peptide reduced the uptake of [125I]IBMF3 to levels seen in controls, confirming the specificity of its cell uptake.

Bottom Line: For this purpose, we custom synthesized a modified F3 peptide analog (F3Cys) incorporating a C-terminal cysteine residue for site-specific attachment of a radioiodinated maleimide conjugating group.These results were also confirmed by ex vivo tissue analysis.No-carrier-added [(125)I]IBMF3 was synthesized by a radioiododestannylation approach in 73% overall radiochemical yield.

View Article: PubMed Central - PubMed

Affiliation: Department of Radiation Oncology, University of Michigan, Ann Arbor, Michigan, United States of America.

ABSTRACT
A radioiodinated derivative of the tumor-homing F3 peptide, (N-(2-{3-[(125)I]Iodobenzoyl}aminoethyl)maleimide-F3Cys peptide, [(125)I]IBMF3 was developed for investigation as a SPECT tumor imaging radioligand. For this purpose, we custom synthesized a modified F3 peptide analog (F3Cys) incorporating a C-terminal cysteine residue for site-specific attachment of a radioiodinated maleimide conjugating group. Initial proof-of-concept Fluorescence studies conducted with AlexaFluor 532 C(5) maleimide-labeled F3Cys showed distinct membrane and nuclear localization of F3Cys in MDA-MB-435 cells. Additionally, F3Cys conjugated with NIR fluorochrome AlexaFluor 647 C(2) maleimide demonstrated high tumor specific uptake in melanoma cancer MDA-MB-435 and lung cancer A549 xenografts in nude mice whereas a similarly labeled control peptide did not show any tumor uptake. These results were also confirmed by ex vivo tissue analysis. No-carrier-added [(125)I]IBMF3 was synthesized by a radioiododestannylation approach in 73% overall radiochemical yield. In vitro cell uptake studies conducted with [(125)I]IBMF3 displayed a 5-fold increase in its cell uptake at 4 h when compared to controls. SPECT imaging studies with [(125)I]IBMF3 in tumor bearing nude mice showed clear visualization of MDA-MB-435 xenografts on systemic administration. These studies demonstrate a potential utility of F3 peptide-based radioligands for tumor imaging with PET or SPECT techniques.

Show MeSH
Related in: MedlinePlus