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In vivo fluorescence lifetime imaging monitors binding of specific probes to cancer biomarkers.

Ardeshirpour Y, Chernomordik V, Zielinski R, Capala J, Griffiths G, Vasalatiy O, Smirnov AV, Knutson JR, Lyakhov I, Achilefu S, Gandjbakhche A, Hassan M - PLoS ONE (2012)

Bottom Line: One of the most important factors in choosing a treatment strategy for cancer is characterization of biomarkers in cancer cells.Assessment of their status in individual patients would facilitate selection of an optimal treatment strategy, and the continuous monitoring of those biomarkers and their binding process to the therapy would provide a means for early evaluation of the efficacy of therapeutic intervention.Thus, this method is useful as a specific marker of the receptor binding process, which can open a new paradigm in the "image and treat" concept, especially for early evaluation of the efficacy of the therapy.

View Article: PubMed Central - PubMed

Affiliation: National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland, United States of America.

ABSTRACT
One of the most important factors in choosing a treatment strategy for cancer is characterization of biomarkers in cancer cells. Particularly, recent advances in Monoclonal Antibodies (MAB) as primary-specific drugs targeting tumor receptors show that their efficacy depends strongly on characterization of tumor biomarkers. Assessment of their status in individual patients would facilitate selection of an optimal treatment strategy, and the continuous monitoring of those biomarkers and their binding process to the therapy would provide a means for early evaluation of the efficacy of therapeutic intervention. In this study we have demonstrated for the first time in live animals that the fluorescence lifetime can be used to detect the binding of targeted optical probes to the extracellular receptors on tumor cells in vivo. The rationale was that fluorescence lifetime of a specific probe is sensitive to local environment and/or affinity to other molecules. We attached Near-InfraRed (NIR) fluorescent probes to Human Epidermal Growth Factor 2 (HER2/neu)-specific Affibody molecules and used our time-resolved optical system to compare the fluorescence lifetime of the optical probes that were bound and unbound to tumor cells in live mice. Our results show that the fluorescence lifetime changes in our model system delineate HER2 receptor bound from the unbound probe in vivo. Thus, this method is useful as a specific marker of the receptor binding process, which can open a new paradigm in the "image and treat" concept, especially for early evaluation of the efficacy of the therapy.

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Related in: MedlinePlus

Confocal microscopy of HER2 positive (A) and negative (B) cells exposed to HER2-Affibody-DyLight488.Blue color shows the cell nuclei labeled with Hoechst 33342 and green color shows the HER2-Affibody-DyLight 488.
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pone-0031881-g010: Confocal microscopy of HER2 positive (A) and negative (B) cells exposed to HER2-Affibody-DyLight488.Blue color shows the cell nuclei labeled with Hoechst 33342 and green color shows the HER2-Affibody-DyLight 488.

Mentions: To understand the mechanism involved in the change in lifetime, we also tested the affinity and specificity of our probe to HER2 receptors in vitro, using cell cultures. It was shown by confocal microscopy that cancer cells, expressing high level of HER2 receptors, have evident membrane accumulation of the fluorescence dye after exposure to HER2-Affibody-Dylight488-conjugate. Neither membrane retention nor intracellular uptake of the probe was observed for HER2-negative MDA-MB-468 cells even after 24-hours of continuous exposure to HER2 targeting probe (Fig. 10).


In vivo fluorescence lifetime imaging monitors binding of specific probes to cancer biomarkers.

Ardeshirpour Y, Chernomordik V, Zielinski R, Capala J, Griffiths G, Vasalatiy O, Smirnov AV, Knutson JR, Lyakhov I, Achilefu S, Gandjbakhche A, Hassan M - PLoS ONE (2012)

Confocal microscopy of HER2 positive (A) and negative (B) cells exposed to HER2-Affibody-DyLight488.Blue color shows the cell nuclei labeled with Hoechst 33342 and green color shows the HER2-Affibody-DyLight 488.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3285647&req=5

pone-0031881-g010: Confocal microscopy of HER2 positive (A) and negative (B) cells exposed to HER2-Affibody-DyLight488.Blue color shows the cell nuclei labeled with Hoechst 33342 and green color shows the HER2-Affibody-DyLight 488.
Mentions: To understand the mechanism involved in the change in lifetime, we also tested the affinity and specificity of our probe to HER2 receptors in vitro, using cell cultures. It was shown by confocal microscopy that cancer cells, expressing high level of HER2 receptors, have evident membrane accumulation of the fluorescence dye after exposure to HER2-Affibody-Dylight488-conjugate. Neither membrane retention nor intracellular uptake of the probe was observed for HER2-negative MDA-MB-468 cells even after 24-hours of continuous exposure to HER2 targeting probe (Fig. 10).

Bottom Line: One of the most important factors in choosing a treatment strategy for cancer is characterization of biomarkers in cancer cells.Assessment of their status in individual patients would facilitate selection of an optimal treatment strategy, and the continuous monitoring of those biomarkers and their binding process to the therapy would provide a means for early evaluation of the efficacy of therapeutic intervention.Thus, this method is useful as a specific marker of the receptor binding process, which can open a new paradigm in the "image and treat" concept, especially for early evaluation of the efficacy of the therapy.

View Article: PubMed Central - PubMed

Affiliation: National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland, United States of America.

ABSTRACT
One of the most important factors in choosing a treatment strategy for cancer is characterization of biomarkers in cancer cells. Particularly, recent advances in Monoclonal Antibodies (MAB) as primary-specific drugs targeting tumor receptors show that their efficacy depends strongly on characterization of tumor biomarkers. Assessment of their status in individual patients would facilitate selection of an optimal treatment strategy, and the continuous monitoring of those biomarkers and their binding process to the therapy would provide a means for early evaluation of the efficacy of therapeutic intervention. In this study we have demonstrated for the first time in live animals that the fluorescence lifetime can be used to detect the binding of targeted optical probes to the extracellular receptors on tumor cells in vivo. The rationale was that fluorescence lifetime of a specific probe is sensitive to local environment and/or affinity to other molecules. We attached Near-InfraRed (NIR) fluorescent probes to Human Epidermal Growth Factor 2 (HER2/neu)-specific Affibody molecules and used our time-resolved optical system to compare the fluorescence lifetime of the optical probes that were bound and unbound to tumor cells in live mice. Our results show that the fluorescence lifetime changes in our model system delineate HER2 receptor bound from the unbound probe in vivo. Thus, this method is useful as a specific marker of the receptor binding process, which can open a new paradigm in the "image and treat" concept, especially for early evaluation of the efficacy of the therapy.

Show MeSH
Related in: MedlinePlus