@article{BruttelWischhusen2014,
  author    = {Bruttel, Valentin S. and Wischhusen, J{\"o}rg},
  title     = {Cancer Stem Cell Immunology: Key to Understanding Tumorigenesis and Tumor Immune Escape?},
  series = {Frontiers in Immunology},
  volume    = {5},
  journal   = {Frontiers in Immunology},
  number    = {360},
  issn      = {1664-3224},
  doi       = {10.3389/fimmu.2014.00360},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-120699},
  year      = {2014},
  abstract  = {Cancer stem cell (CSC) biology and tumor immunology have shaped our understanding of tumorigenesis. However, we still do not fully understand why tumors can be contained but not eliminated by the immune system and whether rare CSCs are required for tumor propagation. Long latency or recurrence periods have been described for most tumors. Conceptually, this requires a subset of malignant cells which is capable of initiating tumors, but is neither eliminated by immune cells nor able to grow straight into overt tumors. These criteria would be fulfilled by CSCs. Stem cells are pluripotent, immune-privileged, and long-living, but depend on specialized niches. Thus, latent tumors may be maintained by a niche-constrained reservoir of long-living CSCs that are exempt from immunosurveillance while niche-independent and more immunogenic daughter cells are constantly eliminated. The small subpopulation of CSCs is often held responsible for tumor initiation, metastasis, and recurrence. Experimentally, this hypothesis was supported by the observation that only this subset can propagate tumors in non-obese diabetic/scid mice, which lack T and B cells. Yet, the concept was challenged when an unexpectedly large proportion of melanoma cells were found to be capable of seeding complex tumors in mice which further lack NK cells. Moreover, the link between stem cell-like properties and tumorigenicity was not sustained in these highly immunodeficient animals. In humans, however, tumor-propagating cells must also escape from immune-mediated destruction. The ability to persist and to initiate neoplastic growth in the presence of immunosurveillance - which would be lost in a maximally immunodeficient animal model - could hence be a decisive criterion for CSCs. Consequently, integrating scientific insight from stem cell biology and tumor immunology to build a new concept of "CSC immunology" may help to reconcile the outlined contradictions and to improve our understanding of tumorigenesis.},
  language  = {en}
}
@article{SchmittEckardtSchlegeletal.2015,
  author    = {Schmitt, Jessica and Eckardt, Sigrid and Schlegel, Paul G and Sir{\´e}n, Anna-Leena and Bruttel, Valentin S and McLaughlin, K John and Wischhusen, J{\"o}rg and M{\"u}ller, Albrecht M},
  title     = {Human parthenogenetic embryonic stem cell-derived neural stem cells express HLA-G and show unique resistance to NK cell-mediated killing},
  series = {Molecular Medicine},
  volume    = {21},
  journal   = {Molecular Medicine},
  number    = {2101185},
  doi       = {10.2119/molmed.2014.00188},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-149170},
  pages     = {185-196},
  year      = {2015},
  abstract  = {Parent-of-origin imprints have been implicated in the regulation of neural differentiation and brain development. Previously we have shown that, despite the lack of a paternal genome, human parthenogenetic (PG) embryonic stem cells (hESCs) can form proliferating neural stem cells (NSCs) that are capable of differentiation into physiologically functional neurons while maintaining allele-specific expression of imprinted genes. Since biparental ("normal") hESC-derived NSCs (N NSCs) are targeted by immune cells, we characterized the immunogenicity of PG NSCs. Flow cytometry and immunocytochemistry revealed that both N NSCs and PG NSCs exhibited surface expression of human leukocyte antigen (HLA) class I but not HLA-DR molecules. Functional analyses using an in vitro mixed lymphocyte reaction assay resulted in less proliferation of peripheral blood mononuclear cells (PBMC) with PG compared with N NSCs. In addition, natural killer (NK) cells cytolyzed PG less than N NSCs. At a molecular level, expression analyses of immune regulatory factors revealed higher HLA-G levels in PG compared with N NSCs. In line with this finding, MIR152, which represses HLA-G expression, is less transcribed in PG compared with N cells. Blockage of HLA-G receptors ILT2 and KIR2DL4 on natural killer cell leukemia (NKL) cells increased cytolysis of PG NSCs. Together this indicates that PG NSCs have unique immunological properties due to elevated HLA-G expression.},
  language  = {en}
}