Understanding the Relationship Between Cell Mechanical Variability and Gene Expression Through Single Cell Experiments and Modeling

Georgia Tech Research Corporation, Atlanta GA

Investigators

Abstract

This award is to study the variation in biomechanical properties of individual healthy and cancerous cells and to relate these properties to the underlying gene expression of important structural, regulatory, and invasive features of the cell. The project will use a new cell sorting device to divide healthy and cancerous cells into softer and stiffer groups. Important biological properties of the cells that predict how they could spread in the body and make new tumors will be measured and compared between the softer and stiffer cell groups. Finally the project will develop a computer model of the cell to explain how differences in which genes are active cause them to be stiff or soft. Knowledge of the biomechanical variation of cancer cells may improve the understanding of cancer metastasis and create a new predictor of a cancer?s spread. This project will provide training opportunities to graduate and undergraduate students on cell mechanics, microfabrication, and cancer biology. The research activities will also promote the recruitment and mentoring of students in cutting-edge scientific techniques through outreach in the Atlanta public high schools. The mechanical integrity of cells is regulated by a dynamic network of structural, cross-linking, and signaling molecules. Therefore, alterations of the mechanical properties of individual cells can reveal important insights into changes in these molecular networks. For example, invasive tumor cells typically soften mechanically, which thereby enhance their capacity to escape from a primary tumor. However, the mechanical variation within a given cell type can be substantial, which not only limits the specificity of cell mechanical measurements, but also poses an intriguing and unanswered question: why do cell mechanical properties vary between similar cells? The objective of this research is to understand how variations in gene expression can lead to variations of cellular mechanics between populations of cells as well as within populations of cells. This study will examine the correlation between cellular mechanical properties (modulus, viscous relaxation, and size) and gene expression, on a cell by cell basis. Two unique experimental measurements will be conducted. First, individual cells will be measured biomechanically with atomic force microscopy and subsequently analyzed for gene expression of mechanically relevant genes previously identified to be differentially expressed from population studies of ovarian healthy and cancer cells. Second, a biophysical cell sorting device will be used to obtain cells of stiffer and softer phenotypes. Each sorted group of cells will be examined for functional and gene expression differences. Finally, the experimental results will be used to inform a multiscale computational model of the cell to explain how biological variation (e.g. crosslinking density) can lead to biophysical variation. The study will delineate the fundamental aspects of the mechanical properties of living cells, particularly cytoskeleton crosslinking, nuclear membrane, and micromechanical changes due to dynamical processes on short time scales (e.g. cell cycle) and longer time scales (e.g. epithelial to mesenchymal transition). This project will answer questions such as whether softer subtypes of noninvasive cells can nonetheless show metastatic-like migration. Knowledge of the biophysics of metastasis of ovarian cancer cells may lead to new diagnostic and treatment approaches based upon detecting and inhibiting specific cell biophysical phenotypes. The project will continue the educational and outreach efforts to increase the number of students pursuing science and engineering. The project will train graduate and undergraduate students in solving interdisciplinary problems by using state-of-the-art experimental and computational methods.