Dissecting the heterogeneity of tumor-initiating cells in hepatobiliary cancers: molecular characterization and targeting of stemness features

Primary liver cancers (PLCs) are among the most rapidly evolving malignant tumors worldwide. An underlying chronic inflammatory liver disease precedes liver cancer development for several decades and creates a pro-oncogenic microenvironment that renders the liver susceptible for malignant transformation. Depending on the primary cellular targets, a diverse range of different morphological and molecular phenotypes is observed in PLCs that frequently impairs therapeutic progress. In this context, the cancer stem cell (CSC) hypothesis provides a plausible explanation for the resulting tumor heterogeneity and implies a rationale for therapeutic strategies beyond the currently used anti-proliferative agents. Thus, eradication of tumors that follow the hierarchic model would require novel therapeutic strategies that specifically target the CSCs. Therefore, a detailed understanding of key molecular features that drive CSC characteristics is imperative to improve the dismal outcome of PLC patients. In the here presented project, we will focus on different key aspects of CSC-biology in PLCs, including intra-tumoral CSC-heterogeneity, prospective isolation of CSCs as well as therapeutic targeting of stemness features. First, we will develop and evaluate a novel robust and reproducible in vitro model of PLC that closely resembles individual phenotypic and molecular characteristics of individual patients. We will then prospectively isolate purified CSCs from human PLCs and apply next-generation whole transcriptome sequencing to define common molecular features and prognostic implications of PLC-CSCs. Subsequently, we will evaluate the therapeutic potential of targeting the identified signaling pathways for CSC-directed therapeutic approaches by using small molecules as well as RNAi. After successful evaluation of the most promising candidates for molecular targeting we will test the applicability of the obtained results for other solid tumors as well as liver metastasis from different primary cancers. Finally, we will directly test the importance of the tumor microenvironment for the heterogeneity of CSCs in PLC by comparing the molecular profiles of CSCs isolated from different intra-tumoral, peri-tumoral and non-tumorous regions. By the end of these investigations we aim at providing a detailed description of the molecular features of PLC-CSCs and delineate the potential of targeting stemness features to complement the existing therapeutic strategies in PLC.