Main focus of the NCT Section “Applied Stem Cell Biology” is the functional and molecular characterization of normal and malignant stem cell regulation. Understanding the regulation of self-renewal and differentiation of stem cells in normal and malignant hematopoiesis is pivotally important to eradicate malignant stem cell-like cells in human leukemias and to develop safe and efficient genetically modified stem cell therapeutics. The section uses large data sets from high throughput sequencing results of clinical gene therapy patients to identify potential stem cell regulatory genes. In these settings, the specific contribution of individual genetically marked clones to the patients’ blood formation was evaluated using highly sensitive methods for identification of viral insertion sites into the genome (Linear amplification-mediated (LAM) PCR and non-restricted (nr-) LAM), allowing an efficient characterization of the whole repertoire of viral integration sites in highly polyclonal samples in pre-clinical and clinical settings. This strategy allowed linking the overexpression of certain zinc finger transcription factors to the development of clonal dominance and leukemia. In addition, the section directly addresses the role of different hematopoietic stem and progenitor types in steady-state hematopoiesis by direct in vivo lentiviral marking. Ongoing projects within the SFB 873 funded by the DFG address the impact of candidate genes on hematopoietic stem cell biology and further stepwise genetic progression towards leukemia by analyzing the impact of specific candidate regulatory genes on hematopoietic stem cell biology in vitro and in vivo.
Many mechanistic principles of normal stem cell biology are applicable to solid malignancies. Understanding the regulation of self-renewal and differentiation of tumor-initiating cells (TIC) in human colon cancer (CRC) and pancreatic cancer is pivotally important to eradicate malignant stem cell-like cells in human cancer. Using a genetic marking approach of primary human CRC in immunodeficient mice, self-renewal and metastasis formation of individual tumor-initiating cells (TIC) has been quantified in vivo, and different types of TIC that drive long-term tumor progression and metastasis formation have been uncovered. Long term TIC (LT-TIC) rebuild tumors after serial transplantation in immunodeficient mice and metastasize. In contrast, tumor transient amplifying cells (T-TAC) with no detectable self-renewal potential only transiently contribute to tumor formation and do not metastasize. Rare delayed contributing TIC (DC-TIC) do not contribute to primary tumor growth, but are recruited to tumor formation following serial transplantation suggesting their mitotic quiescence in vivo. Ongoing projects funded by the DFG and Baden-Württemberg Foundation address characterization and targeting of mitotically quiescent as well as metastasizing and non-metastasizing CRC TIC clones in vivo. Furthermore, deciphering genetic heterogeneity and subclone dynamics of CRC TIC in vivo will provide the basis to develop genotype based eradication strategies directed against this most relevant cell fraction. The “Applied Stem Cell Biology” section is deeply embedded into multiple cross-sectional activities at the Heidelberg campus, e.g. the DFG-funded Clinical Research Unit KFO 227, The Heidelberg Centre for Personalized Oncology (HIPO) and the NCT Precision Oncology Program (POP).
Figure: The role of candidate regulatory genes of hematopoiesis identified in clinical gene therapy studies studies or of genes which regulate self-renewal, tumor-initiation and metastasis in tumor-initiating cells of human colon cancer are evaluated by a systematic stepwise approach in syngeneic or xenogeneic mouse transplantation models. This strategy allows the further identification of cooperating events leading to leukemogenesis, tumorigenesis or metastasis formation. Identified molecular targets will be validated in the marked murine models
Prof. Dr. Hanno Glimm
Abteilung für Translationale Onkologie
Nationales Centrum für Tumorerkrankungen (NCT) Heidelberg
Deutsches Krebsforschungszentrum (DKFZ) Heidelberg