Stem Cells in Development and Disease
Two major developments have occurred in the last decade or so that have changed our view of cellular plasticity and have revolutionized how we can attempt to alter cell fate and study gene function. The first is the Nobel Prize winning discovery by Takahashi and Yamanaka that it only takes four transcription factors (Oct-4, Sox2, KLF4, and c-Myc) to reprogram a differentiated cell (2006). These reprogrammed cells have come to be known as induced pluripotent stem (iPS) cells and are very similar if not identical to pluripotent embryonic stem (ES) cells that can give raise to any cell type in the body. The second discovery is the advent of the CRISPR/Cas9 system and Cas9 variants that have made altering gene function in vitro and in vivo much easier than ever before and has sparked a genome editing revolution. We plan on using these technologies in concert with RNAseq and ChIPseq analysis to better understand the molecular underpinnings of both normal and cancer stem cell states.
Throughout my career I have been extremely fortunate to have been trained and have worked at leading research institutions in Europe (IMP, VIB), Australia (ACBD, ARMI) and Canada (SLRI, and now RIOH/CancerCare Manitoba and Department of Pharmacology and Therapeutics, U of M). My lab has developed novel mouse embryonic (ES) and induced pluripotent stem (iPS) cell-based technologies to study gene function in both normal physiological as well as pathological contexts. Previously, my group has used these technologies in collaboration with other leading experts in their respective fields to address the role of VEGF/VEGF-R signaling and the p53 tumour suppressor in hematopoiesis, neurobiology and cancer. In the last 5 years or so my group has shifted focus and begun to unravel the novel and unexpected role that the SNAI and ZEB family of transcription factors play in both normal hematopoiesis and leukemic transformation with a particular focus on the role of ZEB2 in aggressive forms of T-cell acute lymphoblastic leukemia (ETP-ALL) as well as the roles of ZEB proteins and SNAI1 in acute myeloid leukemia (AML). Research funding is or will be sought in the following 3 areas:
Role of EMT transcription factors in hematopoietic and leukemic stem cell biology
Our lab is studying the role of Snai1 and Zeb1/2 transcription factors in blood cell development (hematopoiesis) and blood cancers (leukemic transformation). These transcription factors have previously been demonstrated to play important roles in epithelial to mesenchymal transition (EMT) events that are necessary for the spread of solid tumor cells to distinct sites in the body (metastasis). Increased expression of these EMT transcription factors (EMT-TFs) has also been associated with the acquisition of cancer stem cell properties that are the driving force behind resistance to drug/radiation therapy and cancer relapse. Our group has previously demonstrated that these EMT-TFs also play important roles in normal blood cell development (Goossens et al., Blood 2011, Li et al, Blood 2017) and in their transformation (Goossens et al, Nature Communications, 2015). We and others have demonstrated that ZEB and SNAI family protein levels have to be tightly regulated during normal hematopoietic development and if they become upregulated or mis-expressed can lead to blocks in hematopoietic differentiation and acquisition of self-renewal properties that allow these aberrant cells to accumulate additional mutations to become leukemic stem cells (LSCs). These LSCs are responsible for giving rise to leukemic transformation, chemoresistance, and disease relapse. One potential mechanism that may be involved is the alterations of key epigenetic modulators and transcriptional programs that may be the target of pharmacological intervention (Goossens et al., Blood 2017). We plan on further investigating how these EMT-TFs control normal hematopoietic stem cells (HSCs) and can drive the development of leukemic stem cells when overexpressed in AML mouse models and using human AML primary samples and cell lines. We aim to identify and functionally validate novel genetic and epigenetic targets of these EMT-TFs using CRISPR/Cas9 gain and loss of function-based strategies as well as combinatorial pharmacological approaches that can be used to terminally differentiate or kill leukemic stem cells.
Role of VEGF signaling in cancer stem cell biology
My group has previously contributed significantly to the understanding of how Vascular Endothelial Growth Factor (VEGF) signalling can affect vascular patterning and function that impacts either directly or indirectly on organ structure and function. One key aspect that has immerged is that of the strong functional link between stem cells and their vascular niche that is essential to maintain stemness properties. This link is best understood in terms of neuronal and hematopoietic stem cells but there is emerging data that VEGF signaling plays essential autocrine as well as paracrine roles in regulating the Cancer Stem Cell Niche in certain solid tumour contexts (for example see Beck et al., Nature, 2011). Using genetic gain/loss of function as well as pharmacological approaches we plan on investigating the role of VEGF signaling in both leukemic stem cells in established AML models as well as its role in brain cancer stem cell biology using newly established glioblastoma models in the mouse.
Development and use of novel ES/iPS and CRISPR/Cas9 models to understand cell lineage identity and transformation
With the advent of iPS technologies the ability to study disease causing mutations in human disease contexts in vitro has expanded rapidly. This ‘disease in a dish’ approach offers new avenues for understanding the molecular underpinnings of disease-causing mutations and offers the opportunity to develop high throughput screening platforms for drug discovery and genome-wide screening applications using CRISPR/Cas9 technologies. We plan on continuing our work in creating human iPS cells from primary AML and control blood cells for the purposes of understanding how major AML driver mutations are capable of causing defects in hematopoietic development and allow the cell to adopt a leukemic stem cell fate. These AML-iPS platforms will complement our existing mouse AML models and will be used to validate the role of novel EMT-TF targets in human AML settings.
Previously our lab has developed very efficient Rosa26 locus targeting approaches for studying gene function in both a Cre/loxP cell-specific and drug-regulated temporal manner (Nyabi et al., NAR 2009, Haenebalcke et al., Stem Cell Rev, 2013). These technologies have been used to develop a novel reprogramming mouse model that allows researchers to more easily study the process of cellular reprogramming and lineage directed differentiation (Haenebalcke et al., Cell Reports, 2013). Using these technologies, we are presently developing novel cell-specific and temporally regulatable Cas9 mice with variants of Cas9 that will allow us to perform gain/loss of function studies in the mouse in a more efficient manner. These mice will be used in the in vivo dissection of key determinants in cancer stem cell state in both AML and in brain cancer models.
More information on Dr. Haigh is also available on the Manitoba Institure of cell Biology Website at https://umanitoba.ca/institutes/manitoba_institute_cell_biology/MICB/Scientists/Haigh.html
Dr. Jody Haigh
Area of Research: Stem Cells in Development and Disease