Background

The Eichmüller lab has been working since many years on the identification of tumor antigens, their HLA-restricted T cell epitopes and the role auto-antibodies in the course of tumor immune-surveillance. Recently, the group has been restructured to form together with the GMP team the new “GMP & T cell Therapy Unit”.
One major topic followed by the research team (Preclinical T cell Research Unit; G183) has been the identification of novel tumor antigen-specific CD4+ T cell epitopes that could be included as vaccine components in tumor immunotherapy approaches or used for immune-monitoring of cancer patients. Focusing on malignant melanoma, we could discover a number of new HLA-DRB1*0301-restricetd epitopes, derived from the melanoma associated differentiation antigens TRP-2 and TRP-1 [1, 2]. Extending our studies to tumor antigens of further cancer entities, we could identify several novel HLA-DRB1*0301- and HLA-DRB1*0401-restricted CD4+ T cell epitopes specific for the breast cancer associated antigen NY-BR-1 [3]. Based on this knowledge we have started to set up a transplantable, NY-BR-1 expressing breast cancer tumor model in HLA-tg mice. Similarly, we initiated a project with focus on the CD4+ T cell/melanoma cell interaction during tumor development. In this setting, OVA-transfected B16F10 melanoma cells will be used expressing the tumor antigen TRP-2 intracellularly, while secreting soluble OVA into the tumor microenvironment. This system should allow us to decipher the functional contributions of TAMs in immune responses against soluble vs intracellular tumor antigen. As it has been described that T cell mediated tumor cell eradication can also happen indirectly, i.e. independent from MHC-molecule expression by tumor cells, we generated a variety of tumor MHC I negative tumor cell lines based on CRISPR/Cas9 technology, that will be used as controls in future experiments (Das et al. in prep.). The generation of respective IAb knock out cell lines by the same technology is currently ongoing.

Another research field followed with great emphasis is the functional investigation of miRNAs in melanoma development [4-6]. Based on a comprehensive miRNA library screen, we could identify several miRNAs modulating hallmarks of tumorigenesis, such as melanoma cell migration and evasion (Weber et al in prep.). Stimulated by these findings, we have begun to screen for miRNAs that influence susceptibility of melanoma cells for recognition by tumor antigen specific CTLs. Once identified, the clinical and therapeutic potential of such miRNA species well be further investigated.

References

Paschen, A.*, Song, M.*, Osen, W*., Nguyen, X. D., Mueller-Berghaus, J., Fink, D., Daniel, N., Donzeau, M., Nagel, W., Kropshofer, H. and Schadendorf, D.,Detection of spontaneous CD4+ T-cell responses in melanoma patients against a tyrosinase-related protein-2-derived epitope identified in HLA-DRB1*0301 transgenic mice. Clin Cancer Res 2005. 11: 5241-5247.

Osen, W., Soltek, S.*, Song, M.*, Leuchs, B., Steitz, J., Tuting, T., Eichmüller, S. B., Nguyen, X. D., Schadendorf, D. and Paschen, A., Screening of human tumor antigens for CD4 T cell epitopes by combination of HLA-transgenic mice, recombinant adenovirus and antigen peptide libraries. PLoS One 2010. 5: e14137.

Gardyan, A.*, Osen, W.*, Zornig, I., Podola, L., Agarwal, M., Aulmann, S., Ruggiero, E., Schmidt, M., Halama, N., Leuchs, B., von Kalle, C., Beckhove, P., Schneeweiss, A., Jager, D. and Eichmüller, S. B., Identification of NY-BR-1-specific CD4(+) T cell epitopes using HLA-transgenic mice. Int J Cancer 2015. 136: 2588-2597.

Hao, S., Luo, C., Abukiwan, A., Wang, G., He, J., Huang, L., Weber, C. E., Lv, N., Xiao, X., Eichmüller, S. B.* and He, D.*, miR-137 inhibits proliferation of melanoma cells by targeting PAK2. Exp Dermatol 2015.

Luo, C., Tetteh, P. W., Merz, P. R., Dickes, E., Abukiwan, A., Hotz-Wagenblatt, A., Holland-Cunz, S., Sinnberg, T., Schittek, B., Schadendorf, D., Diederichs, S. and Eichmüller, S. B., miR-137 inhibits the invasion of melanoma cells through downregulation of multiple oncogenic target genes. J Invest Dermatol 2013. 133: 768-775.

Luo, C., Weber, C. E., Osen, W., Bosserhoff, A. K. and Eichmüller, S. B., The role of microRNAs in melanoma. Eur J Cell Biol 2014. 93: 11-22.

(*equal contribution)

Projects

The following projects are presently running in our lab.

Project 1: Instruction of tumor associated macrophages (TAM) by tumor antigen-specific CD4+ T cells

Using HLA-transgenic mice we have previously identified a panel of HLA-DRB1*03 and HLA-DRB1*04-restricted T cell epitopes specific for human melanoma and breast cancer associated tumor antigens (TRP-1, TRP-2 or NY-BR-1), and established stable CD4+ T cell lines specific for these new T cell epitopes. We are now setting up murine tumor models that will allow us to investigate, whether tumor antigen specific CD4+ T cells can instruct tumor associated macrophages (TAM) presenting HLA-DR-restricted epitopes from ingested tumor antigens, to differentiate into immune-stimulatory M1 like macrophages. In this scenario, tumor antigen-specific CD4+ T cells would hold a central role in reconditioning the tumor micro milieu, thereby sustaining efficient tumor destruction by the immune system.

Project 2: Identification of miRNA impacting CTL susceptibility of melanoma cells

miRNAs are endogenous, small non-coding RNAs post-transcriptionally repressing gene expression by a mechanism known as RNA interference (RNAi). Thus, miRNAs can act as oncogenes or as tumor suppressors, respectively, depending on the gene encoded by the mRNA they target. We have shown that miR137 down regulates expression of the melanoma associated tumor antigen TRP-2 in human and murine melanoma cell lines. Notably, such modulation of tumor antigen expression might alter the susceptibility of the melanoma cell for recognition by tumor antigen-specific CTL, thereby creating link between miRNA expression in melanoma cells and tumor immuno-surveillance. Indeed, we could show, that diminished TRP-2-expression in miR-137-transfected B16F10 cells clearly correlated with reduced susceptibility for CTL recognition as observed in IFNg ELISpot assays performed with a TRP-2-specific CTL line. Based on these results a miRNA library screen has been initiated to identify miRNAs showing modulating effects on the susceptibility of tumor cells for CTL-mediated cytolysis and, most importantly, to determine the mRNA species targeted by the identified miRNAs. As result, miRNAs representing starting points for diagnostic and/or therapeutic interventions should become available.

Cooperations

Prof. Dr. Philipp Beckhove (University Regensburg)
Prof. Dr. Sven Diederichs (DKFZ, B150)
Dr. Jessica Hassel / Prof. Dr. Enk (Dept. of Dermatology, University Hospital Heidelberg)
Prof. Dr. Magnus von Knebel-Döberitz (DKFZ, G105)
Prof. Dr. Rainer König (Jena University Hospital, Jena)
Prof. Dr. Dirk Jäger (NCT Heidelberg)
Prof. Dr. Martin Müller (DKFZ, F035)
Prof. Dr. Rienk Offringa & Dr. Isabel Poschke (DKFZ, G180)
Prof. Dr. Martin Löchelt (DKFZ, F020)
Prof. Dr. Michael Platten (DKFZ, G160, G808)
Prof. Dr. Schneeweiß (Dept. of Gynecology, University Hospital Heidelberg)
Prof. Dr. Florian Schütz / PD Dr. Christoph Domschke (Dept. of Gynecology, University Hospital Heidelberg)
Prof. Dr. Barbara Seliger (Inst. for Medical Immunology, University Hospital Halle)
Dr. Guy Ungerechts / Prof. Dr. Christof von Kalle (DKFZ, G100)

to top