Humbert - Cancer biology, cell polarity and tissue architecture
Cell polarity, or asymmetry, is a fundamental property of all cells and is encoded by an evolutionarily conserved genetic program that coordinates the differential division of stem cells, the positioning of cells within an organ and ultimately the precise architecture of the organ. Disruption of this genetic program leads to the disorganization of tissue and can promote the first steps of cancer. Our laboratory is interested in how cell asymmetry and tissue organization can regulate cancer initiation, progression and metastasis with the ultimate aim to devise therapeutics to help tumours to “reorganize” themselves, thereby stopping the cancer’s growth and spread. In addition we are also interested in how the cell polarity genetic program may be involved in tissue regeneration as well as developmental processes such as blood cell production and function.
To drive this research, we have set up a multidisciplinary approach encompassing state of the art imaging, genetically-engineered mouse models and the use of powerful genetic and chemical screens. We work closely with cancer clinicians, pathologists
Understanding how tissue disorganisation leads to breast cancer
Loss of the proper orientation of cells within a tissue, known as cell polarity, is one of the hallmarks of breast cancer and is correlated with more aggressive and invasive cancers. However how loss of cell polarity occurs and how it contributes at the molecular level to tumour formation remains unknown. Using a number of approaches including RNAi screening, our laboratory has identified a network of genes that mediate the tumour suppressive functions of cell polarity. We aim to use this new molecular information to re-establish normal tissue architecture and hence stop tumour growth.
This project characterizes the top key novel candidates and nodes from this gene network using a variety of biochemical, cell biological and functional assays set up in our laboratory. These include gene knockdown studies in 3D mammary organoid cultures, analysis of genetically engineered mouse models of breast cancer, and mammary gland reconstitution experiments involving the surgical transplantation of RNAi modified mammary stem cells into host mice. In addition, there is also an opportunity to use the powerful genetics of cancer models in Drosophila to complement these studies. The above experiments will provide essential information as to the requirement for intact polarity signaling in breast cancer development and the molecular pathways regulated by the genes that control tissue organization to suppress invasion and tumour growth.
In collaboration with Dr Helena Richardson, LIMS
Funding: NHMRC and National Breast Cancer Foundation
Targeting the early steps of prostate cancer
Prostate cancer is the second most common cause of cancer related deaths in men. Loss of polarity and tissue architecture is a hallmark of epithelial cancer progression and leads to microenvironment alterations critical for tumour evolution and invasion. The importance of tissue architecture in Prostate Cancer prognosis is well recognized, however how it is controlled molecularly is poorly understood. Recent work by our laboratory has shown that key cell polarity regulator proteins are indispensable for prostate tissue homeostasis, and can contribute to prostate cancer initiation and progression.
This project investigates the molecular mechanisms by which the cell polarity network exerts a tumour suppressive function in the prostate epithelium, and assess how loss of cell polarity contributes to the initiation and progression of human prostate cancer. In particular, you shall delineate the molecular events that underpin the early steps of prostate cancer where tissue first become disorganised. Ultimately, your work will determine the potential benefit of targeting the cell polarity signalling preventatively to “reorganize” abnormal pre-cancerous prostate tissue and stop its growth, thus providing an urgently needed novel route of therapeutic intervention. This project incorporates a variety of fundamental laboratory techniques, including mouse genetics, immunohistochemistry, confocal microscopy, 3D organoid prostate culture models (pictured), Patient Derived Xenografts (PDXs), RNAi and CRISPR technology.
In collaboration with Professor Declan Murphy, Peter MacCallum Cancer Centre
Structural and biochemical characterisation of polarity complexes in development and disease
Every cell in our body has an intrinsic orientation (or polarity) that is controlled by a universal set of genes known as polarity genes. Loss of this orientation is a defining early feature in cancers, and has been linked to cancer spread or metastasis. Our team has previously identified the gene Scribble as a new human polarity gene that controls cell orientation and whose deregulation increases the risk of cancer by disorganizing the tissue and by increasing the speed at which cells grow within the tissue. In addition, mutation in Scribble and associated genes can lead to life-threatening birth abnormalities such as spina bifida.
This project will establish how Scribble and its biochemical partners contribute to developmental defects and tumour formation by clarifying their molecular mechanism of action and thus enable targeting of these proteins for therapeutic purposes. To achieve this, you will biochemically characterize the interactions between Scribble and known and novel biochemical partners using a variety of biochemical, high-resolution imaging techniques and functional assays. Using X-ray crystallography and Cryo-electron microscopy (Cryo-EM), you will show in atomic detail how they perform their function. Gaining deeper insight into the nature of the interactions that allow Scribble and its partners to perform its function will be critical to formulate novel anti-cancer compounds that aim to exploit the loss of polarity in cancer cells. All structural and biochemical information will be validated for their functional relevance in our well established mouse and cellular models, and therefore rapidly translated into biological information directly relevant to human cancer patients and their outcome.
In collaboration with Professor Marc Kvansakul, LIMS
How did the red blood cell lose its nucleus?
Red blood cell enucleation (extrusion of the nucleus) is a defining feature of mammalian blood that is required for proper circulation of red blood cells (RBCs) through the microvasculature and increased haemoglobin concentration in the blood. With a large proportion of surgical and cancer patients undergoing blood transfusions as part of their treatment, a major challenge for transfusion medicine is the constant difficulties in obtaining sufficient supplies of specific RBC subtypes. Despite exciting advances in the in vitro production of human red blood cells from hematopoietic, embryonic and induced pluripotent stem cells, the reduced ability of these cultured cells to fully enucleate remains a major hurdle. A better understanding of the enucleation process should lead to improved strategies for the efficient and rapid production of RBCs for autologous (i.e. self generated) patient transfusion.
This project will identify new molecular pathways regulating key steps of enucleation. You will take advantage of powerful in vivo genetic mouse models, in vitro erythroid differentiation system, live imaging and high throughput functional screening platforms set up in the lab to fully characterize the molecular components required for enucleation. These studies will provide a molecular road map of enucleation and help identify pathways that are rate limiting. This information will be used to help circumvent the current limitations of in vitro production of transfusable RBCs and facilitate its transfer from bench to bedside.