Francois Anquez
Axes de recherche
The cell is the core unit of life, and all biological functions arise from the dynamics of interconnected biochemical reactions. These biochemical circuits drive basic cellular functions such as the cell cycle, differentiation, and stress response. In addition to intracellular circuits, cells integrate multiple signals from their environment. For example, juxtacrine, autocrine, and paracrine signaling are examples of cell-to-cell communication that shapes tissue properties at multiple scales.
Although cancer originates from dysregulated biological circuits, tumor progression and the emergence of metastasis are driven by a complex set of rules arising from biochemical networks. To design new therapeutic strategies, it is crucial to understand how biochemical circuits orchestrate biological functions in space and time.
General Approach
We use tools and concepts from physics to try to understand biological systems. Our approach combines live imaging at single cell level with mathematical analysis to uncover how population level properties emerge from indistinguishable but interacting cells.
We hypothetize that the kinetics of biochemical circuits can be described by a mathematical model, ie. a set of differential equations which describe the observed data. The underlying circuits impose spatial and temporal scales as well as explicit form for these equations.
We use live microscopy experiments with a fluorecent reporters of cellular state to monitor dynamics of biological circuits at single cell level. Typically we image a population ~104 cancer cells for up to 5 days. By means of image processing we extract the position and intra-cellular sate of each cells as a function of time.
Given a good guess for relevant variables and single cell quantities, such dataset allows us to infer from the data the equations and from the equations to deduce the topology of putative biochemical circuits. The mathematical model can then be used to predict unobserved dynamic behaviour and confirm its predictive power.
Our tools
Ultra-Wide Field (2D) Microscope :
Our microscope is designed to image very large samples. The system provides environmental control to perform live cell imaging. Altogether it routinely allows brightfield and fluorescence imaging of several thousands of cell for up to 3 weeks. Together with image processing it is a powerfull tool to study dynamics of intra-cellular changes.
Under construction : High-throughput 3D Microscope
This microscope will be able to monitor sequentially several live samples in 3D.
Phenotypic Heterogeneity in cancers
Cancer Stem Cells (CSC) plasticity are a sub-population of cancer cells able to regenerate a heterogeneous tumor. CSC are thought to play a role in treatment resistance and metastasis and they have been proposed as target to improve therapeutic outcomes. It recently became clear that CSC is not a static phenotype but rather tightly regulated by external signals and tumor micro-environment. Importantly radiotherapy or chemotherapy can trigger a reprograming from dierentiated cell to CSC. Understanding the molecular mechanisms at play is crucial to bypass tumor resistance. However the CSC population is rare and reprograming events are unsynchronized. We need a dynamic view of the processes. Analysis of genetic circuits driving reprograming requires both single cell level and time resolved tools. Moreover we need to analyze phenotypic changes in their spatio-temporal context.
Our work provide a workflow for in situ stimulation and long term live 2D/3D imaging of CSC reprograming. We provide high-throughput data for single cell level monitoring and a set of tools for quantitative spatio-temporal analysis.