Potential Indexing of the Invasiveness of Breast Cancer Cells by Mitochondrial Redox Ratios

Abstract

The invasive/metastatic potential of cancer cells is an important factor in tumor progression. The redox ratios obtained from ratios of the endogenous fluorescent signals of NADH and FAD, can effectively respond to the alteration of cancer cells in its mitochondrial energy metabolism. It has been shown previously that the redox ratios may predict the metastatic potential of cancer mouse xenografts. In this report, we aimed to investigate the metabolic state represented by the redox ratios of cancer cells in vitro. Fluorescence microscopic imaging technology was used to observe the changes of the endogenous fluorescence signals of NADH and FAD in the energy metabolism pathways. We measured the redox ratios (FAD/NADH) of breast cancer cell lines MDA-MB-231, MDA-MB-468, MCF-7, and SKBR3. We found that the more invasive cancer cells have higher FAD/NADH ratios, largely consistent with previous studies on breast cancer xenografts. Furthermore, by comparing the fluorescence signals of the breast cancer cells under different nutritional environments, including starvation and addition of glutamine, pyruvate and lactate, we found that the redox ratios still effectively distinguished the highly invasive MDA-MB-231 cells from less invasive MCF-7 cells. These preliminary data suggest that the redox ratio may potentially provide a new index to stratefy breast cancer with different degrees of aggressiveness, which could have significance for the diagnosis and treatment of breast cancer.

Optical Redox Imaging Detects the Effects of DEK Oncogene Knockdown on the Redox State of MDA-MB-231 Breast Cancer Cells

“…Furthermore, since ORI signals are mainly contributed by mitochondrial NADH and FAD, decrease of FAD redox ratio indicates that DEK knockdown likely resulted in a more reduced mitochondrial redox state. Since DEK promotes invasion and metastasis [22], correlated decreases of the redox ratio and invasive potential of DEK knockdown cells are consistent with the previous observations that associate higher or more oxidized redox ratio with cancer aggressiveness [10,12,15]. Note that when comparing malignant to normal cells or tissue, some studies indicate that breast cancer cells in culture have lower optical redox ratio than normal or untransformed cells [13][14] whereas other studies show that breast tumor tissues of clinical patients have higher redox ratio than adjacent normal breast tissue [11].…”

“…In animal models, we found that the triple negative breast cancer (TNBC) cell line MDA-MB-231 induced mouse xenografts with higher metastatic potential and presented a more oxidized state (higher FAD redox ratio) in the localized tumor regions than estrogen-receptor (ER) positive MCF- 7 xenografts, which have lower metastatic potential [12]. It also has been observed in cell cultures that not only the more invasive TNBC MDA-MB-231 cells have higher FAD/NADH ratio than ER+ or HER2+ lines , the rank order of redox ratio of MDA-MB-231 versus another TNBC line MDA-MB-468 is consistent with the rank order of invasive potential [8,[13][14][15]. All these results suggest a correlation or an association between ORI redox ratio and breast cancer aggressiveness as represented by invasive/metastatic potential [8].…”

“…Using the same equipment and parameters as previously described [15], NADH and FAD fluorescence signals were obtained with a DeltaVision Deconvolution Microscope System which has a 300 W xenon lamp as an excitation light source, a 12-bit CCD, and an objective of 40X/0.95 NA (image size 512 × 512, bin 2 × 2, pixel size 0.32mm). The microscope is mounted in a thermally controlled chamber to maintain the samples at 37°C.…”

In vivo multiphoton microscopy detects longitudinal metabolic changes associated with delayed skin wound healing

“…When glucose catabolism increases to accommodate biosynthesis without a proportional increase in oxidative phosphorylation, the intracellular concentration of NADH rises, causing a decrease in the optical redox ratio of FAD/(NADH+FAD) of proliferating cells. Studies using an optical redox ratio to monitor epithelial cancers have related accumulations of NADH to increased proliferative capacity 13 , 23 , 38 , 47 , while more metastatic carcinomas displayed a decrease in the concentration of NADH suggesting that invasive cells favor an oxidative metabolism 39 , 48 , 49 . These trends in the optical redox ratio between proliferative and invasive epithelial cancers match that of keratinocytes during wound re-epithelialization.…”

TLR4/MyD88 signaling determines the metastatic potential of breast cancer cells

“…MDA-MB-231 and MCF-7 represent human breast cell lines with varying metastatic and invasive potential. Generally, MCF-7 cells are non-invasive, while MDA-MB-231 cells are highly invasive ( 29 ) and used to examine the mechanisms of breast cancer metastasis ( 30 ). The present study used these two cellular models of invasion to examine the association between TLR4, MyD88 and HMGB1 expression levels and metastatic potential.…”