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ABSTRACT: Methods
An engineered cystine knot peptide, R01, that recognizes integrin ?v?6 was labeled with Atto 740 (A740) and evaluated for its specific cell uptake and its sensitivity threshold. A740-R01 was injected via the tail vein into nude mice xenografted with A431 (integrin ?v?6-positive) or 293T (integrin ?v?6-negative) tumors. Photoacoustic and fluorescence scans of tumors were acquired before and at 0.5, 1, 2, and 4 h after injection of A740-R01. Dynamic photoacoustic scans of various normal organs were also acquired. Ex vivo fluorescence imaging of tissues was performed 1 h after injection.Results
The A740-R01 demonstrated integrin ?v?6-dependent binding to A431 cells in culture. Sensitivity studies indicated that the probe may potentially detect lesions as small as 1 or 6 mm3 by fluorescence or photoacoustic imaging, respectively. The photoacoustic and fluorescence signals of A431 xenografts at 1 h after injection were 1.87 ± 0.25 arbitrary units (AU) and 8.27 ± 0.87 AU, respectively. Target specificity was confirmed by low tumor uptake in 293T tumors at 1 h after injection (1.07 ± 0.15 AU and 1.10 ± 0.14 AU for photoacoustic and fluorescence signals, respectively). A740-R01 exhibited hepatobiliary clearance marked by high uptake in the liver, spleen, and intestine but low uptake in the kidneys.Conclusion
A740-R01 specifically targeted integrin ?v?6 with low nanomolar affinity. A740-R01 was able to detect integrin ?v?6 both in vitro and in vivo by photoacoustic and fluorescence imaging. A740-R01 is able to detect ?v?6-positive tumors in living subjects and may have clinical application in cancer diagnosis and real-time image-guided surgery.
SUBMITTER: Zhang C
PROVIDER: S-EPMC5367447 | biostudies-literature | 2016 Oct
REPOSITORIES: biostudies-literature
Zhang Chao C Kimura Richard R Abou-Elkacem Lotfi L Levi Jelena J Xu Lingyun L Gambhir Sanjiv Sam SS
Journal of nuclear medicine : official publication, Society of Nuclear Medicine 20160526 10
Photoacoustic imaging is a nonionizing biomedical imaging modality with higher resolution and imaging depth than fluorescence imaging, which has greater sensitivity. The combination of the 2 imaging modalities could improve the detection of cancer. Integrin α<sub>v</sub>β<sub>6</sub> is a cell surface marker overexpressed in many different cancers. Here, we report the development and evaluation of a dye-labeled cystine knot peptide, which selectively recognizes integrin α<sub>v</sub>β<sub>6</sub ...[more]