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01.12.2014 | Research | Ausgabe 1/2014 Open Access

Journal of Hematology & Oncology 1/2014

A novel mycobacterial Hsp70-containing fusion protein targeting mesothelin augments antitumor immunity and prolongs survival in murine models of ovarian cancer and mesothelioma

Journal of Hematology & Oncology > Ausgabe 1/2014
Jianping Yuan, Satoshi Kashiwagi, Patrick Reeves, Jean Nezivar, Yuan Yang, Nadiah Hashim Arrifin, Mai Nguyen, Gilberte Jean-Mary, Xiaoyun Tong, Paramjit Uppal, Svetlana Korochkina, Ben Forbes, Tao Chen, Elda Righi, Roderick Bronson, Huabiao Chen, Sandra Orsulic, Timothy Brauns, Pierre Leblanc, Nathalie Scholler, Glenn Dranoff, Jeffrey Gelfand, Mark C Poznansky
Wichtige Hinweise

Electronic supplementary material

The online version of this article (doi:10.​1186/​1756-8722-7-15) contains supplementary material, which is available to authorized users.

Competing interests

The authors declare that they have no competing interests.

Authors’ contributions

JY played a role in the design of the experiments, acquisition, analysis, and interpretation of the data, and writing the manuscript. PR, JN, YY, NHA, MN, GJ-M, XT, SK, HC, PU, BF, TC and PL participated in the performance of experiments. SK and TB were involved in design of the experiments. RB was involved in data analysis. ER was involved in setting up murine ovarian cancer model. SO provided the murine ovarian cancer model. NS provided the plasmid that encodes an scFv fragment specific to MSLN and the recombinant P4 scFv protein. GD, NS and SO gave constructive input on experimental design and data analysis. JG played a role in conception and design of the fusion protein. MP and JG were involved in the conceptualization and design of the study, analysis and interpretation of datasets and in writing the manuscript. All authors read and approved the final manuscript.



Although dendritic cell (DC) vaccines are considered to be promising treatments for advanced cancer, their production and administration is costly and labor-intensive. We developed a novel immunotherapeutic agent that links a single-chain antibody variable fragment (scFv) targeting mesothelin (MSLN), which is overexpressed on ovarian cancer and mesothelioma cells, to Mycobacterium tuberculosis (MTB) heat shock protein 70 (Hsp70), which is a potent immune activator that stimulates monocytes and DCs, enhances DC aggregation and maturation and improves cross-priming of T cells mediated by DCs.


Binding of this fusion protein with MSLN on the surface of tumor cells was measured by flow cytometry and fluorescence microscopy. The therapeutic efficacy of this fusion protein was evaluated in syngeneic and orthotopic mouse models of papillary ovarian cancer and malignant mesothelioma. Mice received 4 intraperitoneal (i.p.) treatments with experimental or control proteins post i.p. injection of tumor cells. Ascites-free and overall survival time was measured. For the investigation of anti-tumor T-cell responses, a time-matched study was performed. Splenocytes were stimulated with peptides, and IFNγ- or Granzyme B- generating CD3+CD8+ T cells were detected by flow cytometry. To examine the role of CD8+ T cells in the antitumor effect, we performed in vivo CD8+ cell depletion. We further determined if the fusion protein increases DC maturation and improves antigen presentation as well as cross-presentation by DCs.


We demonstrated in vitro that the scFvMTBHsp70 fusion protein bound to the tumor cells used in this study through the interaction of scFv with MSLN on the surface of these cells, and induced maturation of bone marrow-derived DCs. Use of this bifunctional fusion protein in both mouse models significantly enhanced survival and slowed tumor growth while augmenting tumor-specific CD8+ T-cell dependent immune responses. We also demonstrated in vitro and in vivo that the fusion protein enhanced antigen presentation and cross-presentation by targeting tumor antigens towards DCs.


This new cancer immunotherapy has the potential to be cost-effective and broadly applicable to tumors that overexpress mesothelin.

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Additional file 1: Figure S1: scFvMTBHsp70 binds to 40L mesothelioma cells. 40L cells were stained with scFvMTBHsp70 or MTBHsp70, followed by mouse anti-MTBHsp70, and Donkey anti-mouse Alexa Fluor 594. Cells were observed using a Nikon Eclipse TiE fluorescence microscope. A, Representative pictures from three independent experiments. Scale bar, 10 μm. B, Images were analyzed using the NIS-Elements AR Microscope Imaging Software. Mean Fluorescence Intensity was analyzed using ImageJ. P values were determined using One-Way ANOVA followed by Turkey’s multiple comparison tests. ****,p < 0.0001. (TIFF 2 MB)
Additional file 2: Figure S2: scFvMTBHsp70 or MTBHsp70 plus P4 scFv treatment does not lead to infiltration of inflammatory cells into abdominal or intestinal mesothelial tissues. Samples of abdominal wall and intestine were prepared from C57BL/6 mice that had previously received multiple i.p. injections of scFvMTBHsp70, MTBHsp70 plus P4 scFv or saline as described in the Methods section. Sections of these tissues were stained with H&E, and images were acquired on a Zeiss Axio A1 microscope. Representative images from 3 animals per treatment group are shown. No detectable level of mononuclear cell or granulocyte infiltrate within mesothelial tissues was seen in any sampled tissues. Scale bar, 20 μm. (TIF 6 MB)
Additional file 3: Figure S3: scFvMTBHsp70 treatment does not affect numbers of tumor-infiltrating CD8+ or Foxp3+ T cells. (A) Representative images of intratumoral CD8+ and Foxp3+ T cells from saline (n = 3), scFvMTBHsp70 (n = 3), or MTBHsp70 plus P4 scFv (n = 3) -treated mice. Mouse spleen sections were used as positive controls: CD8+ and Foxp3+ T cells are clearly evident in the sections. Scale bar, 20 μm. (B) Numbers of CD8+ and Foxp3+ cells were quantified from 3–5 randomized fields. (TIF 9 MB)
Additional file 4: Figure S4: Validation of in vivo depletion of CD8+ cells in FVB/NJ mice. Mice were injected i.p. with 200 μg of anti-CD8 mAb or an isotype-matched irrelevant rat IgG2a as described in Methods. All the mice were bled from the tail vein and the depletion of CD8+ cells was examined by flow cytometry analysis of peripheral blood cells stained with fluorophore-conjugated anti-CD8 on days 7 and 28 after tumor inoculation. (A) Representative results of flow analyses on 10 mice per group and reported as the percentage of CD8+ cells in lymphocytes. (B) CD8+ cells in the mice treated with isotype IgG2a or anti-CD8 mAb were compared. ***,p< 0.001. (TIFF 1017 KB)
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