FLIM and Mitometer enable metabolic profiling and tracking phenotypic changes in mitochondria in cancer cells
The hallmark of metabolic alteration of increase glycolysis, i.e. Warburg effect, in cancer cells together with atypical extracellular matrix structure may be responsible for tumor cell aggressiveness and drug resistance. While it is it known that tumor cells stiffen the ECM as the tumor progression occurs, a direct relationship between ECM stiffness and altered metabolism has not been explicitly measured. Here we apply the phasor approach technique in fluorescence lifetime imaging microscopy (FLIM) to measure metabolic alteration as a function of ECM mechanics. We imaged and compared triple-negative breast cancer (TNBC) cells to non-cancerous cells on various ECM stiffness. Our results show that TNBC exhibit a decreased fraction of bound NADH, (indicative of glycolysis,) with increasing substrate stiffness. All other cell lines showed little to no change in fraction bound NADH on the varying collagen densities. Dysregulation of mitochondrial motion may contribute to the fueling of bioenergy demands in metastatic cancer. To measure mitochondria motion and analyze their fusion and fission events, we developed a new algorithm called “mitometer” that is unbiased, and allows for automated segmentation and tracking of mitochondria in live cell 2D and 3D time-lapse images. Together, the automated segmentation and tracking algorithms and the innate user interface make Mitometer a broadly accessible tool.?
Dr. Digman was awarded a doctorate degree in Chemistry with specialization in Biochemistry from the University of Illinois at Chicago in 2003. She did her postdoctoral work in the Department of Physics at the University of Illinois at Urbana-Champaign in biophysics until this lab moved to the University of California Irvine. She became Optical Bio-Core Director until she joined the BME department in 2013. Her research lab is focused on developing novel biophysical and optical tools to study biological questions with the goal of applying the gained knowledge to the advancement of human medicine. Dr. Digman is AIMBE Fellow, Scialog Fellow, Allen Distinguished Investigator in Immunometabolism, and has won several awards including the NSF-CAREER award, the Hellman Fellowship, the Fluorescence Young Investigator Award from the Biophysical Society, the Faculty Innovation in Teaching award and has received the Henry Samueli Career Development Chair