Mobile lipid production after confluence and pH stress in perfused C6 cells

Abstract

NMR-visible mobile lipid (ML) has been observed in aggressive tumors and also in in vitro tumor cell models subjected to growth-inhibiting conditions, such as confluence or low-pH stress. The aim of the present study was to determine if ML production after confluence or low pH stress in a cultured cell model of brain tumor is due to growth arrest alone. ML was observed in situ by one- and two-dimensional (1)H NMR in viable but growth-arrested C6 glioma cells superfused for a period of 48 h after harvesting. The rate of ML production in cells harvested at subconfluence was compared to the rate in cells confluent for one cell cycle and to the rate in subconfluent-harvested cells superfused at low pH (pH 6.1). Confluent-harvested cells produced ML at a markedly greater rate than that of cells harvested at subconfluence, suggesting the involvement of prior cell-cell contact rather than simple growth arrest. A high rate was also observed in subconfluent-harvested cells subjected to low pH, indicating that ML in pH-stressed cells also does not arise from growth arrest alone. Furthermore, two-dimensional data on the degree of unsaturation of the ML fatty acyl chains and one-dimensional (31)P and two-dimensional (1)H NMR data on the GPC content of the cells suggest distinct metabolic pathways for the production of ML following confluence and low-pH stress.

Apoptosis is associated with triacylglycerol accumulation in Jurkat T-cells

“…CH 2 and CH 3 contents were determined by integration and normalised relative to TSP and cell number. Lactate contribution to the CH 2 resonance was subtracted following deconvolution (Barba et al, 2001) using xedplot software (Bruker). …”

Group IVA Phospholipase A2 Is Necessary for the Biogenesis of Lipid Droplets

“…Materials- [5,6,8,9,11,12,14, H]Arachidonic acid ([ 3 H]AA) (200 Ci/mmol) was purchased from American Radiolabeled Chemicals, and [9,10-3 H]palmitic acid (49 Ci/mmol) from Amersham Biosciences. PLA 2 inhibitors methylarachidonyl fluorophosphonate (MAFP) and bromoenol lactone (BEL) were from Cayman Chemical Co., and arachidonyl trifluoromethyl ketone (AACOCF 3 ) and pyrrolidine-2 (Py-2, catalog number 525143) were from Calbiochem.…”

“…Lipid availability is not the only physiological parameter governing the occurrence of LD. Stress has been shown in many instances to induce LD formation; cells reaching confluence (12,13), undergoing apoptosis (14,15), exposed to acidic pH (10,16), or engaged in inflammation (17) are some examples. In fact, cellular stress detected by means of NMR, where mobile lipids in LD generate specific signals (16,18), is the basis for promising imaging techniques for tumor diagnosis and treatment (18,19).…”

Phosphorous metabolites and steady-state energetics of transformed fibroblasts during three-dimensional growth

“…In most cases, enhanced phospholipid biosynthesis and reduced phospholipid breakdown were observed in long-term chronic situations such as tumors and high phosphomonoester (PME) levels have been hypothesized to be the best biochemical marker to distinguish some cancerous from normal tissues (16,17,43,52,55,62,65) and to monitor tumor treatment outcome (69,75). Some but not all of these observations might be due to the fact that under certain conditions PC strongly correlates with cell proliferation (4,6,21,26,62,68,72,82). Ting et al (80) compared the metabolism of different human breast cancer cells and normal mammary epithelial cells with a similar proliferative activity.…”