Experimental hematology, Myeloproliferative Neoplasms, Lab PD Dr. med. Alexandre Theocharides
Myeloproliferative neoplasms (MPN) are pre-leukemic hematopoietic stem cell disorders characterized by increased proliferation of one or more hematopoietic cell lineages. The incidence of MPN is highest in the aging population and MPN prevalence will significantly increase in the next decades. Although recent advances in diagnosis and subsequent therapies led to improved MPN patient survival, most patients die from cardiovascular events or from transformation to acute leukemia.
The goal of our research is to gain understanding of the pathogenesis of MPN and to translate this knowledge into the development of novel therapeutic approaches. As murine models only partially reflect the complexity of human disease, a substantial part of the experiments are performed with primary patient cells
in vitro and
in vivo in patient-derived xenograft models. For this we have access to multiple next-generation immunodeficient mice that the group of M.G. Manz has generated within a consortium. I am also an attendig physician of the outpatient clinic for patients with MPN in the division of hematology at the University Hospital Zurich. The research platform and the strong interactions with the division of hematology constitute an ideal and attractive infrastructure to assess efficacy of therapeutic compounds and collaborate with the pharmaceutical industry to further translate evidence established in our laboratory to clinical trials.
Development of a patient-derived xenograft model for myelofibrosis
I started my doctoral studies in February
2015 with a focus on developing a patient-derived xenograft (PDX) mouse model
for myelofibrosis (MF). Pre-clinical PDX mouse models have emerged as powerful
tools for investigating normal and leukemic stem cells (HSCs and LSCs), as well
as HSC and LSC heterogeneity. A growing number of models have been developed
for aggressive malignancies, such as acute leukemias (AML). However,
engraftment of less aggressive malignancies, like MF, is often limited. MF is a
HSC disorder characterized by bone marrow fibrosis that has the potential to
transform into AML depending on the clonal evolution of MF stem cells.
Treatment refractoriness and disease progression remain a major challenge;
therefore, there is need for a suitable model. The aim of my project is to use
next-generation mice to develop a pre-clinical MF PDX model that will serve as
a tool to understand the disease pathogenesis and assess response to novel
The role of Calreticulin mutations in the pathogenesis of MPN
Recently, our group has shown that MPN patients with homozygous CALR mutations develop a maturation defect in Myeloperoxidase (MPO), a GP normally folded by CALR (Theocharides et al., Blood 2016). Based on these findings, we hypothesize that CALR mutations affect GP maturation and potentially may lead to mutant-specific protein-protein interactions in signaling pathways that further contribute to the pathogenesis of MPN. In a biased approach, we study the interaction with wildtype and mutant CALR with our “model-GP” MPO. This will allow us to identify potential chaperone defects of mutant CALR. Using the CRISPR-Cas9 system and lentiviral expression vectors we generated several CALR knockout or mutant cell lines to investigate the functional implications of CALR mutants on GP maturation. In addition, we conduct a proteome-wide screen in CALR-mutated primary samples for proteins with altered structures caused by either misfolding or conformational changes.
I joined the Theocharides lab in April 2017 as a PhD student in Cancer Biology to start a collaborative project with the lab of Bernd Wollscheid (ETHZ). I have studied Biomedical Sciences in the Netherlands and have a strong personal interested in performing translational cancer research.
In my project, I perform research on the role of Calreticulin mutations in myeloproliferative neoplasms (MPN). MPN are a family of blood diseases that originate from hematopoietic stem cells. By discovering the mechanisms that drive disease, therapeutics targeting these alterations can be developed to improve treatment of patients suffering from MPN. Calreticulin, is a protein that normally functions as a chaperone that ensures correct folding of cellular proteins. To find out how mutations in this protein alter the cell and drive pathogenesis of MPN, we take an integrative unbiased approach. In this approach, we combine various techniques to look at the cellular proteome, transcriptome, and Calreticulin interactome, and study how these change upon mutation of Calreticulin using CRISPR/Cas9 technology.