In vitro drug susceptibility of two strains of the wildlife trypanosome, Trypanosoma copemani: A comparison with Trypanosoma cruzi
The antineoplastic and immune modulating action of ether-linked lysophosphatidylcholines was described several years ago (1-5). They are cytotoxic against tumour cells in vitro and in vivo, but may also induce differentiation in malignant cells (6-10). They also activate cytotoxic macrophages (11,12) and inhibit neoplastic cell invasion in normal tissues (13,14). In addition edelfosine (ET-18-OCH3), an alkyllysophosphocholine, is capable to induce apoptosis in certain cells (15-18). Apoptosis, the programmed cell death, has recently attracted much interest in terms of both the therapy of tumorous tissues and its mechanism to resisting therapy. It is an endogenously induced physiological cell death, which is morphologically distinguishable from necrosis (19-21). Apoptosis is a process in which extracellular endogenous stimuli activate a genetic program to start a specific series of events to disintegrate a cell without an inflammatory process. The characteristic morphological features of apoptosis are cell shrinkage, membrane blebbing, chromatin condensation and nuclear fragmentation, formation of apoptotic bodies, and engulfment by neighbouring cells or phagocytosis. Miltefosine (hexadecylphosphocholine, HPC) is a derivative of the alkylphosphocholines, which differ from the „conventional“ alkyllysophosphocholines with regards to the missing glycerol backbone. HPC is a prototype of alkylphosphocholines, which show anticancer properties superior to the alkyllysophosphocholine edelfosine. We investigate the apoptotic potential of HPC and its effect on cellular metabolism as can be accessed through NMR spectroscopy. As the cell membranes are one target of this drug treatment, the membrane composition and variations of their composition needed to be analyzed. Multinuclear NMR spectroscopy was used to non-invasively and non-destructively detect low molecular weight metabolites in viable cells or in vitro with better resolution and higher sensitivity on cell extracts. P-NMR of living cells was able to monitor the energy status under treatment (22) and diffusion-weighted H-NMR spectroscopy (23) to follow up changes in the cell volume. The study of cell extracts requires no separation or derivatisation of its components. All metabolites are simultaneously detectable. NMR spectroscopy of cellular extracts reflects the steady state concentration of metabolites at the time of extraction. With P-NMR spectroscopy it is possible to detect the relative composition of phospholipids, while the lipid and fatty acid metabolism could be followed up by C-NMR spectroscopy using non-radioactive C-labelled glucose.