It is known that cancer cells don’t live on glass slides, yet the vast majority of images related to cancer biology come from the cells being photographed on flat, two-dimensional surfaces; images that are sometimes used to make conclusions about the behaviour of cells that normally reside in a more complex environment. Now, researchers at University of Texas Southwestern have developed a new high-resolution microscope which visualizes cancer cells in 3D, recording how they are signaling to other parts of their environment, and revealing unprecedented views of how cancer cells survive and disperse within living things. The team state that their microscope may bring a deeper understanding of the molecular mechanisms that drive cancer cell behaviour, as it enables high-resolution imaging in more real-world environments. The opensource study is published Developmental Cell.
Previous studies show that cells in vivo, within the living organism, function in complex 3D- microenvironments consisting of cells and extracellular matrix. Recent studies show that in addition to the well-known pathways governed by the biochemical properties of the extracellular matrix, a wide range of cell behaviours including cancer cell invasion and progenitor cell differentiation are controlled by the mechanical properties of the cellular microenvironment. Although past work has shown that the microenvironmental properties of the stroma mediate critical functions, such as drug resistance in cancer cells, there is very little understanding of how a cell’s microenvironment influences the spatial and temporal organization of molecular signaling pathways.
The current study used a novel 3D- microscope to image different kinds of skin cancer cells from patients. The 3D- microscopy technique was able to show that the mechanical properties of the microenvironment regulate the transition of melanoma cells from actin-driven protrusion to blebbing, with the group presenting tools to quantify how cells manipulate individual collagen fibers. The new technique was also able to quantify the local concentration of actin and phosphatidylinositol 3-kinase signaling on the surfaces of cells deep within 3D- collagen matrices and track the many small membrane protrusions that appear in these more physiologically relevant environments.
The team state that since their approach facilitates the quantitative study of intracellular processes in more realistic and precisely controllable microenvironments, they term it microenvironmental selective plane illumination microscopy (meSPIM). They go on to add that the 3D- quantitative analysis enabled by this approach will open up the study of cell signaling and behavior in diverse but mechanically and chemically well-defined 3D- microenvironments. The lab conclude that the microscope control software and image analytical code are freely available to the global medical community.
The team surmise that this is a first step toward understanding 3D- biology in tumour microenvironments and since these kinds of images may be too complicated to interpret by the naked eye alone, the next step will be to develop powerful computer platforms to extract and process the information. For the future, the researchers state that there is clear evidence that the environment strongly affects cellular behaviour, thus, the value of cell culture experiments on glass should at least be questioned.