Kurzfassung

Correlation between high circulating levels of DKK1 and a poor prognosis in various cancers is shown. Furthermore, DKK1 supports an immunosuppressive milieu in the tumour microenvironment by supporting the generation and function of myeloid derived suppressor cells (MDSC). DKK1 inhibits the WNT-ß-catenin pathway and competitively binds to the WNT co-receptors low density lipoprotein receptor- related protein (LRP) -5 and -6, which induce the degradation of the ß-catenin complex. The...Correlation between high circulating levels of DKK1 and a poor prognosis in various cancers is shown. Furthermore, DKK1 supports an immunosuppressive milieu in the tumour microenvironment by supporting the generation and function of myeloid derived suppressor cells (MDSC). DKK1 inhibits the WNT-ß-catenin pathway and competitively binds to the WNT co-receptors low density lipoprotein receptor- related protein (LRP) -5 and -6, which induce the degradation of the ß-catenin complex. The expression of LRP 5 and 6 is also shown on the surface of dendritic cells (DCs) and after binding of WNTs, differentiation of DCs is moved to a regulatory state which is characterized by high release of IL-10, TGF-ß and VEGF and low secretion of pro inflammatory cytokines like IL-6 and TNFα. Tolerogenic DCs promote immune suppression by regulatory Tcells. DCs in the microenvironment of tumors show a similar phenotype. Therefore, prevented binding of DKK1 to LRP5/6 can strengthen tumor immune response by increased maturation of DCs. Therefore the DKK-1 inhibitor DKN-01 were used to prevent the binding of DKK1 (Dickkopf-related protein 1) to the WNT co-receptors.
The mixed lymphocyte cultures (MLC) with gastric- and colon cancer cells enable the direct characterization of DKN-01-induced TCLs for their means to activate and improve maturation of iDCs and to stimulate human immune cells, such as CTL and CD4 cells or to block T-reg cells.
We isolate primary human immune cells from buffy coats of healthy blood donors to coculture them with different gastric- and colon carcinoma cells incubated with DKN-01 and later with HLA-A2 corresponding T-cells for their means to differentiate DC and activate CTL. The coincubation of DCs can also be done in combination with chemotherapeutic drugs as well as with other immunogenic target agents. Furthermore, we characterize the DC-mediated TAA cross-presentation in more details after phagocytosis.
Read out and quantification of antigen directed CTL responses will be based on the distinct methods as described. The inhibiton of Tregs can also be analysed.
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