A heat-inducible gene expression system for a dominant negative version of a TGF-b-receptor reveals antitumor activity in a rodent tumor model.

F. NOYAN; CHRISTOPH KLEIN; RICARDO A. DEWEY

Wilsede, Germany

Jornada; XX. Jahrestagung der Kind-Philipp-Stiftung für Leukämieforschung. Zentrum für Frauen- Kinder- und Jugendmedizin Klinik für pädiatische Hämatologie und Onkologie; 2007

Kind-Philipp-Stiftung für Leukämieforschung. Zentrum für Frauen- Kinder- und Jugendmedizin Klinik für pädiatische Hämatologie und Onkologie

In an attempt to design novel therapeutic strategies against malignant brain tumors, we hypothesized that spatial and temporal control of transgene expression may allow for the administration of immunomodulatory or cytotoxic agents at the site of tumor. Here, we assess the potential of the HSP70b promotor to control lentivirus-mediated gene expression in tumor-infiltrating hematopoietic cells.  We generated a series of lentiviral vectors and characterized transgene expression in vitro and in vivo. HSP driven GFP expression in different cell lines could be induced by elevated temperatures up to 20 fold. Next, we assessed HSP70b-controlled transgene expression in vivo in a rodent tumor model using the glioma cell line GL261. In tumor-infiltrating hematopoietic cells, we observed a 10-15 fold elevated expression level of GFP as compared to basal expression levels in spleen, suggesting a localized induction of HSP70b due to tumor microenvironment.   Finally, using a dominant negative TGF-b-receptor construct (TGF-b-DNR), we provide evidence that local expression in tumor cells enhances antitumor immunity. Tumor size and volume was decreased up to 10 fold in mice expressing HSP70b-controlled TGF-b-DNR compared to non-expressing TGF-b-DNR animals. The anti-tumoral effect using HSP70b controlled transgene expression was comparable to vectors with constitutive expression of TGF-b-DNR.   In summary, HSP70b-mediated transgene expression in hematopoietic cells may provide a novel strategy for controlled release of immunmodulatory molecules to induce anti-tumor therapies.