Phenotypic Therapy and Immune Escape in Cancer

Project 2Identification of regulators of therapy-induced epithelial mesenchymal plasticity in pancreatic cancer

Cellular heterogeneity represents a key challenge in understanding and effectively targeting therapy resistance in cancer patients. Chromatin-dependent mechanisms dynamically regulate gene expression networks that again control cellular features such as epithelial-mesenchymal (E-M) plasticity and stemness, both of which have been linked to therapy resistance. The chromatin landscape of tumor cells and the tumor microenvironment reciprocally regulate each other, where particularly tumor-immune interactions increasingly move into the research focus and offer novel targeting strategies. Our preliminary results provide evidence for E-M plasticity as a key process in therapy resistance in pancreatic cancer (PDAC); among different molecular subtypes and upon drug-induced pressure, e.g. the inhibition of RAS/MAPK signaling. Transition into mesenchymal states goes along with a significant change in the tumor architecture when modelled in genetically engineered mice. Here, we aim to characterize the molecular dynamics of E-M plasticity upon RAS-MAPK targeting using comprehensive molecular profiling. We will identify master genes and chromatin regulators for validation in clinical and experimental PDAC cohorts. Candidate targets will be functionally validated in advanced 2D/3D in vitro and in vivo models. We will analyze single tumor cells with epithelial and mesenchymal features using DEPArrayTM-based isolation to further understand distinct cell populations and their regulators. We will use a novel reporter system to validate candidate factors and to screen for drugs interfering with E-M transition. One candidate regulator, KDM5B/JARID1B, will be characterized in detail using genetic and pharmacological gene modulation experiments as well as functional analyses including a newly generated loss-of-function mouse model. As E-M transition both depends on and regulates microenvironmental signals, we will characterize distinct tumor subpopulations and their interaction with non-tumoral (ie. immune and stromal) cell subsets using multiplexed imaging and spatial computational analysis in murine and human PDAC. Our analyses of the intimate interaction of chromatin regulation with the microenvironment will conceptually, methodologically, and mechanistically benefit from the Clinical Research Unit PhenoTImE. We envision that the intense interaction with the other groups characterizing resistance mechanisms in distinct hard-to-treat cancer entities will allow dissection of conserved chromatin-microenvironmental networks. The obtained results shall generate mandatory preclinical data packages for the development of future clinical trials, a task often underestimated given the enormous biological and pharmacological complexity. However, the high expertise of the West German Cancer Center in early clinical trials makes this a realistic achievement while also the preclinical aspects of PhenoTImE will benefit from the local scientific setup.



Prof Dr Jens Siveke
West German Cancer Center
University Hospital Essen

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