Pyruvate uptake is increased in highly invasive ovarian cancer cells under anoikis conditions for anaplerosis, mitochondrial function, and migration

Abstract

Anoikis resistance, or the ability for cells to live detached from the extracellular matrix, is a property of epithelial cancers. The "Warburg effect," or the preference of cancer cells for glycolysis for their energy production even in the presence of oxygen, has been shown to be evident in various tumors. Since a cancer cell's metastatic ability depends on microenvironmental conditions (nutrients, stromal cells, and vascularization) and is highly variable for different organs, their cellular metabolic fluxes and nutrient demand may show considerable differences. Moreover, a cancer cell's metastatic ability, which is dependent on the stage of cancer, may further create metabolic alterations depending on its microenvironment. Although recent studies have aimed to elucidate cancer cell metabolism under detached conditions, the nutrient demand and metabolic activity of cancer cells under nonadherent conditions remain poorly understood. Additionally, less is known about metabolic alterations in ovarian cancer cells with varying invasive capability under anoikis conditions. We hypothesized that the metabolism of highly invasive ovarian cancer cells in detachment would differ from less invasive ovarian cancer cells and that ovarian cancer cells will have altered metabolism in detached vs. attached conditions. To assess these metabolic differences, we integrated a secretomics-based metabolic footprinting (MFP) approach with mitochondrial bioenergetics. Interestingly, MFP revealed higher pyruvate uptake and oxygen consumption in more invasive ovarian cancer cells than their less invasive counterparts. Furthermore, ATP production was higher in more invasive vs. less invasive ovarian cancer cells in detachment. We found that pyruvate has an effect on highly invasive ovarian cancer cells' migration ability. Our results are the first to demonstrate that higher mitochondrial activity is related to higher ovarian cancer invasiveness under detached conditions. Importantly, our results bring insights regarding the metabolism of cancer cells under nonadherent conditions and could lead to the development of therapies for modulating cancer cell invasiveness. oxidative phosphorylation; metabolomics; Warburg effect; bioenergetics; cancer migration and anoikis OVARIAN CANCER REMAINS A LEADING CAUSE of gynecological malignancy-related deaths and is often detected in the late stages, when the cancer has already metastasized (5). Of all ovarian cancer diagnoses, most are classified as epithelial ovarian carcinoma (17). In the process of epithelial ovarian cancer metastasis, cancer cells can remain viable while they are suspended in peritoneal fluid in the peritoneal cavity. A normal epithelial cell would in this environment undergo anoikis or epithelial cell death due to detachment, first coined by Frisch and Francis (8) in 1994. However, cancer cells, including ovarian cancer cells, can survive without extracellular matrix attachment and are thus considered anoikis resistant. Anoikis resistance in cancer has been widely studied from t...

Nitric Oxide Mediates Metabolic Coupling of Omentum-Derived Adipose Stroma to Ovarian and Endometrial Cancer Cells

“…We showed that when O-ASC-secreted arginine is depleted (using L-arginase) or when O-ASC-secreted factors induced increased NO synthesis in cancer cells is inhibited (using L-NAME), there is a decline in the growth rate of both ovarian cancer and endometrial cancer cells. It was previously reported by our group that ovarian cancer cells secrete considerable amount of citrulline, thereby indicating high NOS activity and arginine utilization (33). Here, our data showed that ovarian cancer and endometrial cancer cells use arginine produced by O-ASCs and generate citrulline.…”

Metabolism in cancer metastasis

“…Consistent with the requirements, increased cancer invasiveness under deadherent conditions is associated with higher mitochondrial activity, elevated ATP production, pyruvate uptake, and oxygen consumption. 29 Surrounding stromal cells may facilitate the acquisition of a proinvasive metabolic profile. Under aerobic conditions, 15,16 Glucose utilization Glycolysis 1 Respiratory chain 17,18 Glutamine metabolism NADPH generation, oxaloacetate regeneration for the TCA cycle 10,11 Creatine synthesis for ATP regeneration 17 Peroxide Reduced production through mitochondrial hyperpolarization 9 Production essential for anchorage independence 17,[19][20][21][22] Outcome Biosynthesis 11 Overcome ATP deficit 18 to avoid anoikis 15 glycolysis is induced in mesenchymal stem cells adjacent to osteosarcoma cells.…”

How does cancer cell metabolism affect tumor migration and invasion?

“…These differences in metabolism would have an effect on cell migration, and pyruvate may be used by highly invasive ovarian cancer cells to migrate in attached conditions and, thus, may enhance metastatic potential. 35 The enzymes in glycolysis also play important roles in tumor migration and invasion. Phosphoglucose isomerase (PGI, also known as glucose-6-phosphate isomerase or phosphohexose isomerase) is a housekeeping cytosolic enzyme that catalyzes the conversion of glucose-6-phosphate into fructose-6-phosphate in the second step of glycolysis.…”