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    • "TPP has advantages over other peptides that are currently being evaluated, as the latter are restricted to targeting specific receptors on specific types of tumor cells [7]–[11]. Another potential advantage of TPP as a therapeutic vehicle is that memHsp70 is expressed on a large proportion of tumors and its expression on tumor cells can be induced/increased using relevant chemotherapeutic agents [59] and radiation therapy [60]. The proportion of patients to which the TPP can be administered can therefore be increased by standard therapies. "
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    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.
    PLoS ONE 08/2014; 9(8):e105344. DOI:10.1371/journal.pone.0105344 · 3.23 Impact Factor
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    • "Expression of HSP is induced even under nonstress conditions, including those of the cell cycle, development, and differentiation [24-26]. Regarding the literature, even radiation could induce stress proteins in vitro [27]. Hurwitz et al. (2010) could show that radiation therapy induces expression of HSP70 in patients with prostate cancer [28]. "
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    ABSTRACT: Preoperative radiotherapy and chemotherapy in patients with head and neck cancer result in changes to the vessels that are used to construct microsurgical anastomoses. The aim of the study was to investigate quantitative changes and HSP70 expression of irradiated neck recipient vessels and transplant vessels used for microsurgical anastomoses. Of 20 patients included in this study five patients received neoadjuvant chemoradiation, another five received conventional radiotherapy and 10 patients where treated without previous radiotherapy. During surgical procedure, vessel specimens where obtained by the surgeon. Immunhistochemical staining of HSP70 was performed and quantitative measurement and evaluation of HSP70 was carried out. Conventional radiation and neoadjuvant chemoradiation revealed in a thickening of the intima layer of recipient vessels. A increased expression of HSP70 could be detected in the media layer of the recipient veins as well as in the transplant veins of patients treated with neoadjuvant chemoradiation. Radiation and chemoradiation decreased the HSP70 expression of the intima layer in recipient arteries. Conventional radiation led to a decrease of HSP70 expression in the media layer of recipient arteries. Our results showed that anticancer drugs can lead to a thickening of the intima layer of transplant and recipient veins and also increase the HSP70 expression in the media layer of the recipient vessels. In contrast, conventional radiation decreased the HSP70 expression in the intima layer of arteries and the media layer of recipient arteries and veins. Comparing these results with wall thickness, it was concluded, that high levels of HSP70 may prevent the intima layer of arteries and the media layer of vein from thickening.
    Radiation Oncology 07/2011; 6(1):81. DOI:10.1186/1748-717X-6-81 · 2.55 Impact Factor
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    ABSTRACT: The major stress-inducible heat shock protein 70 (Hsp70) is frequently overexpressed in highly aggressive tumors, and elevated intracellular Hsp70 levels mediate protection against apoptosis. Following therapeutic intervention, such as ionizing irradiation, translocation of cytosolic Hsp70 to the plasma membrane is selectively increased in tumor cells and therefore, membrane Hsp70 might serve as a therapy-inducible, tumor-specific target structure. Based on the IgG1 mouse monoclonal antibody (mAb) cmHsp70.1, we produced the Hsp70-specific recombinant Fab fragment (Hsp70 Fab), as an imaging tool for the detection of membrane Hsp70 positive tumor cells in vitro and in vivo. The binding characteristics of Hsp70 Fab towards mouse colon (CT26) and pancreatic (1048) carcinoma cells at 4 °C were comparable to that of cmHsp70.1 mAb, as determined by flow cytometry. Following a temperature shift to 37 °C, Hsp70 Fab rapidly translocates into subcellular vesicles of mouse tumor cells. Furthermore, in tumor-bearing mice Cy5.5-conjugated Hsp70 Fab, but not unrelated IN-1 control Fab fragment (IN-1 ctrl Fab), gradually accumulates in CT26 tumors between 12 and 55 h after i.v. injection. In summary, the Hsp70 Fab provides an innovative, low immunogenic tool for imaging of membrane Hsp70 positive tumors, in vivo.
    Radiotherapy and Oncology 06/2011; 99(3):313-6. DOI:10.1016/j.radonc.2011.05.051 · 4.36 Impact Factor
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