Insight into redox regulation of apoptosis in cancer cells with multiparametric live-cell microscopy

Abstract

Cellular redox status and the level of reactive oxygen species (ROS) are important regulators of apoptotic potential, playing a crucial role in the growth of cancer cell and their resistance to apoptosis. However, the relationships between the redox status and ROS production during apoptosis remain poorly explored. In this study, we present an investigation on the correlations between the production of ROS, the redox ratio FAD/NAD(P)H, the proportions of the reduced nicotinamide cofactors NADH and NADPH, and caspase-3 activity in cancer cells at the level of individual cells. Two-photon excitation fluorescence lifetime imaging microscopy (FLIM) was applied to monitor simultaneously apoptosis using the genetically encoded sensor of caspase-3, mKate2-DEVD-iRFP, and the autofluorescence of redox cofactors in colorectal cancer cells upon stimulation of apoptosis with staurosporine, cisplatin or hydrogen peroxide. We found that, irrespective of the apoptotic stimulus used, ROS accumulation correlated well with both the elevated pool of mitochondrial, enzyme-bound NADH and caspase-3 activation. Meanwhile, a shift in the contribution of bound NADH could develop independently of the apoptosis, and this was observed in the case of cisplatin. An increase in the proportion of bound NADPH was detected only in staurosporine-treated cells, this likely being associated with a high level of ROS production and their resulting detoxification. The results of the study favor the discovery of new therapeutic strategies based on manipulation of the cellular redox balance, which could help improve the anti-tumor activity of drugs and overcome apoptotic resistance.

Assessing the impact of extracellular matrix fiber orientation on breast cancer cellular metabolism

“…We therefore used the ORR as an additional measure of the metabolic activity of the cells on both scaffolds. The ORR was calculated as I FAD+ /(I FAD+ +I NADH ), with a decrease in ORR indicating an increase in glycolytic activity [ 74 , 75 ].…”

Genetically Encoded Fluorescent Sensors for SARS-CoV-2 Papain-like Protease PLpro

“…For example, a large collection of target proteins fused with GFP variants as well as GFP-based sensors are available [ 16 , 22 ]. In addition, endogenous cofactors NAD(P)H and FAD, which show the metabolic status of the cell [ 23 , 24 ], can potentially be imaged together with mScarlet-LKGG-miRFP670.…”

FLIM of NAD(P)H in Lymphatic Nodes Resolves T-Cell Immune Response to the Tumor

“…Previously, NADPH contribution has been observed in several studies using FLIM. For example, it was found in cancer cells undergoing apoptosis [ 37 ], human embryonic kidney cells upon metabolic perturbations [ 10 ], in stem cells during adipogenic differentiation [ 38 ], and in liver tissue [ 17 , 39 ]. In each case, increased NADPH production was associated with different processes.…”