Dataset Information

Tumor imaging and targeting potential of an Hsp70-derived 14-mer peptide.

ABSTRACT:

Background

We have previously used a unique mouse monoclonal antibody cmHsp70.1 to demonstrate the selective presence of a membrane-bound form of Hsp70 (memHsp70) on a variety of leukemia cells and on single cell suspensions derived from solid tumors of different entities, but not on non-transformed cells or cells from corresponding 'healthy' tissue. This antibody can be used to image tumors in vivo and target them for antibody-dependent cellular cytotoxicity. Tumor-specific expression of memHsp70 therefore has the potential to be exploited for theranostic purposes. Given the advantages of peptides as imaging and targeting agents, this study assessed whether a 14-mer tumor penetrating peptide (TPP; TKDNNLLGRFELSG), the sequence of which is derived from the oligomerization domain of Hsp70 which is expressed on the cell surface of tumor cells, can also be used for targeting membrane Hsp70 positive (memHsp70+) tumor cells, in vitro.

Methodology/principal findings

The specificity of carboxy-fluorescein (CF-) labeled TPP (TPP) to Hsp70 was proven in an Hsp70 knockout mammary tumor cell system. TPP specifically binds to different memHsp70+ mouse and human tumor cell lines and is rapidly taken up via endosomes. Two to four-fold higher levels of CF-labeled TPP were detected in MCF7 (82% memHsp70+) and MDA-MB-231 (75% memHsp70+) cells compared to T47D cells (29% memHsp70+) that exhibit a lower Hsp70 membrane positivity. After 90 min incubation, TPP co-localized with mitochondrial membranes in memHsp70+ tumors. Although there was no evidence that any given vesicle population was specifically localized, fluorophore-labeled cmHsp70.1 antibody and TPP preferentially accumulated in the proximity of the adherent surface of cultured cells. These findings suggest a potential association between membrane Hsp70 expression and cytoskeletal elements that are involved in adherence, the establishment of intercellular synapses and/or membrane reorganization.

Conclusions/significance

This study demonstrates the specific binding and rapid internalization of TPP by tumor cells with a memHsp70+ phenotype. TPP might therefore have potential for targeting and imaging the large proportion of tumors (?50%) that express memHsp70.

SUBMITTER: Gehrmann M

PROVIDER: S-EPMC4148261 | biostudies-literature | 2014

REPOSITORIES: biostudies-literature

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Publications

Tumor imaging and targeting potential of an Hsp70-derived 14-mer peptide.

Gehrmann Mathias M Stangl Stefan S Foulds Gemma A GA Oellinger Rupert R Breuninger Stephanie S Rad Roland R Pockley Alan G AG Multhoff Gabriele G

PloS one 20140828 8

<h4>Background</h4>We have previously used a unique mouse monoclonal antibody cmHsp70.1 to demonstrate the selective presence of a membrane-bound form of Hsp70 (memHsp70) on a variety of leukemia cells and on single cell suspensions derived from solid tumors of different entities, but not on non-transformed cells or cells from corresponding 'healthy' tissue. This antibody can be used to image tumors in vivo and target them for antibody-dependent cellular cytotoxicity. Tumor-specific expression o ...[more]

PMID: 25165986

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Project description:Integrin αvβ6 is overexpressed in a variety of cancers, and its expression is often associated with poor prognosis. Therefore, there is a need to develop affinity reagents for noninvasive imaging of integrin αvβ6 expression since it may provide early cancer diagnosis, more accurate prognosis, and better treatment planning. We recently engineered and validated highly stable cystine knot peptides that selectively bind integrin αvβ6 with no cross-reactivity to integrins αvβ5, α5β1, or αvβ3, also known to be overexpressed in many cancers. Here, we developed a single photon emission computed tomography (SPECT) probe for imaging integrin αvβ6 positive tumors. Cystine knot peptide, S02, was first conjugated with a single amino acid chelate (SAAC) and labeled with [(99m)Tc(H2O)3(CO)3](+). The resulting probe, (99m)Tc-SAAC-S02, was then evaluated by in vitro cell uptake studies using two αvβ6 positive cell lines (human lung adenocarcinoma cell line HCC4006 and pancreatic cancer cell line BxPC-3) and two αvβ6 negative cell lines (human lung adenocarcinoma cell line H838 and human embryonic kidney cell line 293T). Next, SPECT/CT and biodistribution studies were performed in nude mice bearing HCC4006 and H838 tumor xenografts to evaluate the in vivo performance of (99m)Tc-SAAC-S02. Significant differences in the uptake of (99m)Tc-SAAC-S02 were observed in αvβ6 positive vs negative cells (P < 0.05). Biodistribution and small animal SPECT/CT studies revealed that (99m)Tc-SAAC-S02 accumulated to moderate levels in antigen positive tumors (∼2% ID/g at 1 and 6 h postinjection, n = 3 or 4/group). Moreover, the probe demonstrated tumor-to-background tissue ratios of 6.81 ± 2.32 (tumor-to-muscle) and 1.63 ± 0.18 (tumor-to-blood) at 6 h postinjection in αvβ6 positive tumor xenografts. Co-incubation of the probe with excess amount of unlabeled S02 as a blocking agent demonstrated significantly reduced tumor uptake, which is consistent with specific binding to the target. Renal filtration was the main route of clearance. In conclusion, knottin peptides are excellent scaffolds for which to develop highly stable imaging probes for a variety of oncological targets. (99m)Tc-SAAC-S02 demonstrates promise for use as a SPECT agent to image integrin αvβ6 expression in living systems.

Dataset Information

Tumor imaging and targeting potential of an Hsp70-derived 14-mer peptide.

Background

Methodology/principal findings

Conclusions/significance

Publications

Tumor imaging and targeting potential of an Hsp70-derived 14-mer peptide.

Similar Datasets

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