Cholesterol, its biosynthetic precursors and the cholesterol-lowering drug compactin were able to inhibit the growth of human erythroleukemia K562 cells. Compactin, farnesyldiphosphate and cholesterol were cytotoxic by the induction of apoptosis (programmed cell death, PCD). Compactin doubled the number of apoptotic cells compared to control numbers, whereas farnesyldiphosphate and cholesterol led to a fivefold increase in PCD over the control levels. At variance with cholesterol, cholesterol esters did not affect K562 cell viability and apoptotic body formation, regardless of chain length and degree of saturation. Compactin and farnesyldiphosphate reduced the membrane cholesterol content, thus increasing membrane fluidity. Conversely, cholesterol treatment reduced the membrane fluidity by increasing cholesterol content in the lipid bilayer. Unlike farnesyldiphosphate, the other cholesterol precursors and cholesterol esters were ineffective in increasing the cholesterol content and, thereby, the fluidity of cell membranes. Compactin and cholesterol precursors, apart from farnesyldiphosphate, did not affect the amount of the farnesylated proteins Ras and lamin B in the cytosolic and the membrane fractions of K562 cell extracts, whereas farnesyldiphosphate reduced the content of both proteins in both fractions. The level of lamin B in K562 cytosol and membranes was also reduced by cholesterol treatment, which did not significantly affect the amount of Ras. These findings highlight the role of cholesterol in promoting PCD.Keywords : apoptosis ; cholesterol ; lamin B ; membrane ; Ras.Apoptosis (programmed cell death, PCD) is a genetically syl anchor, belongs to a superfamily containing more than 50 small GTPases (Peeper et al., 1997). Ras is implicated in cell controlled process, which counteracts mitosis in regulating cell number (Kerr et al., 1972). Several cell-death pathways are trig-growth control and, therefore, associated with several human cancers. Lamin B, a 67-kDa farnesylated protein, has a structural gered by membrane receptors and are executed through membrane-derived lipid messengers (Hale et al., 1996; Skowronski role in nuclear membranes (Hancock, 1993; Gibbs et al., 1994).Lamin B is cleaved by caspases (Kumar and Lavin, 1996) in the et al., 1996). Recently, we have reported profound changes in the cell membrane composition of human erythroleukemia K562 pathway of Fas-mediated PCD (Greidinger et al., 1996; Peter et al., 1996). Thus, a perturbation of cholesterol biosynthesis can cells forced into apoptosis by treatment with transforming growth factor β1, alone or in combination with cisplatin (Mac-be expected to affect the cells by altering the membrane cholesterol content (that is, membrane properties) and/or the level of carrone et al., 1996). These changes at the membrane level might be the basis for specific recognition and elimination of farnesylated proteins (that is, regulation of cell proliferation).Inhibitors of cholesterol biosynthesis, such as lovastatin and apoptotic cells by macrophage...

Background:Oxidative stress and neuronal cell death have been implicated in the pathogenesis of Alzheimer disease (AD). Considering that the glutathione transferase (GST) supergene family encodes isoenzymes that appear to be critical in protection against oxidative stress, we aimed at determining the various GSTP1, GSTM1, and GSTT1 polymorphisms and ApoE genotypes to investigate their role as susceptibility genes for late-onset AD (LOAD). Methods: We included 210 LOAD patients and 228 healthy controls matched for age, sex, and educational level in our case-control genetic association study. GSTM1 and GSTT1 genotypes were studied by conventional PCR, whereas GSTP1 and ApoE genotypes were determined by real-time PCR on the LightCycler. Results: We found a significant association between LOAD and the GSTP1*C allelic variant [odds ratio (OR) ‫؍‬ 1.9; P <0.05], but no association between the GSTM1 and GSTT1 deleted genotypes and LOAD. In addition, a preliminary result suggested that carriers of both the GSTP1*C and ApoE ⑀4 allelic variants were at increased risk of LOAD (OR ‫؍‬ 19.98; P <0.0001).

Neuroblastoma, one of the most common pediatric solid tumors, originates from the peripheral sympathetic nervous system and is responsible for approximately 15% of all childhood cancer deaths. Among the several antineoplastic drugs used in neuroblastoma chemotherapeutic protocols, topoisomerase inhibitors (i.e., etoposide) represent the most commonly used. Several resistance mechanisms limit the clinical success of topoisomerase-targeting drugs, mainly reducing the ability of neoplastic cells to start programmed cell death when exposed to antineoplastic drugs. The aim of this study was to determine, by means of proteomics, potential markers of etoposide resistance in human neuroblastoma cell lines as well as to investigate protein levels and modifications possibly involved in the onset of resistance. The etoposide resistant clone showed overexpression of the following proteins: peroxiredoxin 1, beta-galactoside soluble lectin binding protein, vimentin (three protein spots), heat shock 27 kDa protein (two protein spots) and heterogeneous nuclear ribonucleoprotein K. In addition, we also found down-regulation of dUTP pyrophosphatase. This investigation might represent a first step towards the development of novel prognostic markers of neuroblastoma chemotherapy.