Endogenous Two-Photon Fluorescence Imaging Elucidates Metabolic Changes Related to Enhanced Glycolysis and Glutamine Consumption in Precancerous Epithelial Tissues

Abstract

Alterations in the balance between different metabolic pathways used to meet cellular bioenergetic and biosynthetic demands are considered hallmarks of cancer. Optical imaging relying on endogenous fluorescence has been used as a noninvasive approach to assess tissue metabolic changes during cancer development. However, quantitative correlations of optical assessments with variations in the concentration of relevant metabolites or in the specific metabolic pathways that are involved have been lacking. In this study, we use high-resolution, depth-resolved imaging, relying entirely on endogenous two-photon excited fluorescence in combination with invasive biochemical assays and mass spectrometry to demonstrate the sensitivity and quantitative nature of optical redox ratio tissue assessments. We identify significant differences in the optical redox ratio of live, engineered normal and precancerous squamous epithelial tissues. We establish that while decreases in the optical redox ratio are associated with enhanced levels of glycolysis relative to oxidative phosphorylation, increases in glutamine consumption to support energy production are associated with increased optical redox ratio values. Such mechanistic insights in the origins of optical metabolic assessments are critical for exploiting fully the potential of such noninvasive approaches to monitor and understand important metabolic changes that occur in live tissues at the onset of cancer or in response to treatment.

Valve interstitial cell contractile strength and metabolic state are dependent on its shape

“…The decrease in the optical redox ratio has been used previously to monitor precancerous transformations, 28 cell proliferation during wound healing, 21 and as an early indicator of cellular differentiation in mesenchymal stem cells. 20 Our results show that the redox ratio can serve as an indicator of VIC proliferation and to a lesser extent, phenotypic activation.…”

Correlating two-photon excited fluorescence imaging of breast cancer cellular redox state with seahorse flux analysis of normalized cellular oxygen consumption

“…2,3 Since the first publication by Chance et al, 4 the ORR has been used in a broad range of applications spanning from cancer detection and diagnosis to predicting drug response to monitoring cellular function and stem cell differentiation. [5][6][7][8][9] Unlike competing quantitative techniques with which the cells have to be lyzed, [10][11][12] TPEF microscopy provides a nondestructive, real-time, and label-free method for quantifying cellular metabolism. It enables the spatial mapping of metabolic rate at the submicrometer scale with minimum interruption of normal cell function.…”

Differential Expression of PGC1α in Intratumor Redox Subpopulations of Breast Cancer

“…NADH and Fp signals are contributed mainly by mitochondria. The redox ratio can be regarded as a surrogate indicator of the mitochondrial redox state and is shown to correlate linearly with NAD-coupled redox potential NAD + /NADH as determined biochemically [6, 7]. Our studies have shown that the heterogeneity-based mitochondrial redox indices (NADH, Fp and FpR) can differentiate between tumors with different levels of aggressiveness and between premalignant and normal tissues [8–10].…”