Uptake of synthetic low density lipoprotein by leukemic stem cells — a potential stem cell targeted drug delivery strategy

Chronic Myeloid Leukemia (CML) stem/progenitor cells, which over-express Bcr-Abl, respond to imatinib by a reversible block in proliferation without significant apoptosis. As a result, patients are unlikely to be cured owing to the persistence of leukemic quiescent stem cells (QSC) capable of initiating relapse. Previously, we have reported that intracellular levels of imatinib in primary primitive CML cells (CD34<sup>+</sup>38<sup>lo/−</sup>), are significantly lower than in CML progenitor cells (total CD34<sup>+</sup>) and leukemic cell lines. The aim of this study was to determine if potentially sub-therapeutic intracellular drug concentrations in persistent leukemic QSC may be overcome by targeted drug delivery using synthetic Low Density Lipoprotein (sLDL) particles. As a first step towards this goal, however, the extent of uptake of sLDL by leukemic cell lines and CML patient stem/progenitor cells was investigated. Results with non-drug loaded particles have shown an increased and preferential uptake of sLDL by Bcr-Abl positive cell lines in comparison to Bcr-Abl negative. Furthermore, CML CD34<sup>+</sup> and primitive CD34<sup>+</sup>38<sup>lo/−</sup> cells accumulated significantly higher levels of sLDL when compared with non-CML CD34<sup>+</sup> cells. Thus, drug-loading the sLDL nanoparticles could potentially enhance intracellular drug concentrations in primitive CML cells and thus aid their eradication

Cholesterol Homeostasis in Two Commonly Used Human Prostate Cancer Cell-Lines, LNCaP and PC-3

BACKGROUND:Recently, there has been renewed interest in the link between cholesterol and prostate cancer. It has been previously reported that in vitro, prostate cancer cells lack sterol-mediated feedback regulation of the major transcription factor in cholesterol homeostasis, sterol-regulatory element binding protein 2 (SREBP-2). This could explain the accumulation of cholesterol observed in clinical prostate cancers. Consequently, perturbed feedback regulation to increased sterol levels has become a pervasive concept in the prostate cancer setting. Here, we aimed to explore this in greater depth. METHODOLOGY/PRINCIPAL FINDINGS:After altering the cellular cholesterol status in LNCaP and PC-3 prostate cancer cells, we examined SREBP-2 processing, downstream effects on promoter activity and expression of SREBP-2 target genes, and functional activity (low-density lipoprotein uptake, cholesterol synthesis). In doing so, we observed that LNCaP and PC-3 cells were sensitive to increased sterol levels. In contrast, lowering cholesterol levels via statin treatment generated a greater response in LNCaP cells than PC-3 cells. This highlighted an important difference between these cell-lines: basal SREBP-2 activity appeared to be higher in PC-3 cells, reducing sensitivity to decreased cholesterol levels. CONCLUSION/SIGNIFICANCE:Thus, prostate cancer cells are sensitive to changing sterol levels in vitro, but the extent of this regulation differs between prostate cancer cell-lines. These results shed new light on the regulation of cholesterol metabolism in two commonly used prostate cancer cell-lines, and emphasize the importance of establishing whether or not cholesterol homeostasis is perturbed in prostate cancer in vivo

Consensus-Phenotype Integration of Transcriptomic and Metabolomic Data Implies a Role for Metabolism in the Chemosensitivity of Tumour Cells

Using transcriptomic and metabolomic measurements from the NCI60 cell line panel, together with a novel approach to integration of molecular profile data, we show that the biochemical pathways associated with tumour cell chemosensitivity to platinum-based drugs are highly coincident, i.e. they describe a consensus phenotype. Direct integration of metabolome and transcriptome data at the point of pathway analysis improved the detection of consensus pathways by 76%, and revealed associations between platinum sensitivity and several metabolic pathways that were not visible from transcriptome analysis alone. These pathways included the TCA cycle and pyruvate metabolism, lipoprotein uptake and nucleotide synthesis by both salvage and de novo pathways. Extending the approach across a wide panel of chemotherapeutics, we confirmed the specificity of the metabolic pathway associations to platinum sensitivity. We conclude that metabolic phenotyping could play a role in predicting response to platinum chemotherapy and that consensus-phenotype integration of molecular profiling data is a powerful and versatile tool for both biomarker discovery and for exploring the complex relationships between biological pathways and drug response

Cholesterol turnover in acute myelogenous leukemia with special emphasis on regulation of low density lipoprotein receptor expression in leukemic cells

Cellular cholesterol requirements are met by receptor mediated uptake of cholesterol in low density lipoprotein (LDL) particles andlor by endogenous synthesis, the rate limiting enzyme in the synthesis pathway being 3-hydroxy-3-methylglutary coenzyme A (HMG-CoA) reductase. Expressions of both the LDL receptor and HMG-CoA reductase genes are normally under end product repression by cellular cholesterol. Leukemic cells from patients with acute myelogenous leukemia (AML) have a higher receptor mediated uptake of LDL than normal white blood and nucleated bone marrow cells and the levels of plasma cholesterol are decreased in AML patients. Previous studies have also found that LDL is a promising drug carrier candidate for cytotoxic agents. Expression of the drug transporter protein P- glycoprotein (Pgp) causes the multidrug resistance phenotype and recent studies suggest that Pgp may be involved in cholesterol transport. The aims of the studies were to investigate the mechanisms behind elevated LDL receptor activity and hypocholesterolemia in AML and to investigate LDL receptor and HMG-CoA reductase activities in drug resistant leukemic cell lines. In comparison with mononuclear blood cells from healthy individuals, cells from AM patients had elevated LDL receptor and HMG-CoA reductase activities as well as elevated RNA levels for both genes. LDL receptor RNA levels correlated weakly with protein activity which increased more than RNA levels during cholesterol deprivation suggesting post RNA regulation of the LDL receptor. AML cells showed a decreased sensitivity to the downregulatory effect of sterols on LDL receptor activity. The median sterol concentration for 50% inhibition (IC50) Of LDL receptor activity was more than five times higher for AML cells than for normal cells and IC50 values correlated with the LDL receptor activity in freshly isolated AM cells (r = 0.53, P = 0.007) indicating that the elevated receptor activity may be a result of decreased sterol sensitivity. In spite of a higher growth rate, normal human fibroblasts, at low cell densities, were more sensitive to downregulation of LDL receptor activity by sterols and had a lower LDL receptor activity than subconfluent cells demonstrating that growth modulation of sterol sensitivity takes place in normal cells. When mononuclear blood cells from healthy subjects were incubated in AML cell conditioned medium LDL receptor activity was induced by up to 240% and sensitivity to sterols decreased compared with cells incubated in control medium. LDL receptor activity in freshly isolated AML cells correlated with stimulation of LDL receptor activity in normal cells (r-0.79, P= 0.004). AML cells were also stimulated by their own conditioned medium. Interleukin-2 (IL-2) and IL-4 stimulated LDL receptor activity by up to 150% and caused a decreased sensitivity to sterols in normal cells. The stimulatory effect of AML cell conditioned medium on normal cells was not reversed by neutralizing IL-2, IL-4, IL6, or oncostatin M antibodies. Levels of 7alpha-hydroxy-4-cholesten-3- one, reflecting hepatic bile acid production, were markedly reduced in plasma from AML patients as compared with healthy subjects while 7-dehydrocholesterol levels, reflecting hepatic cholesterol synthesis, were similar. We found that 5 out of 5 drug resistant K562 cell lines had 2-10 times higher LDL uptake than the parental K562 cells. Drug resistant HL60 cell lines also had higher uptake of LDL than the parental cell line. Elevated uptake of LDL by drug resistant leukemic cell lines was not associated with an increased Pgp expression. It is concluded that AML cells with elevated LDL uptake have a decreased sensitivity to the downregulatory effect of sterols on LDL receptor expression and that AML cells secrete a factor, possibly a growth factor, which stimulates LDL receptor expression. A paracrine or autocrine stimulation by such a factor could be responsible for the elevated LDL uptake in AML cells. AML patients have a reduced production of bile acids which could lead to cholesterol malabsorbition and hypocholesterolemia and several drug resistant leukemic cell lines had an elevated uptake of LDL which supports the idea of using LDL as a drug carrier

Att leva med schizofreni: en kvalitativ studie om drabbade och anhöriga

The purpose of this study was to examine the subjective experience of schizophrenia. Four people, two of them diagnosed with schizophrenia and two relatives, were interviewed. The themes selected were development of the disease, recovery, belief in the future, the role of families and siblings, stigmatization and the relationship between violent crimes and mental illness. The development and experience of schizophrenia as well as the recovery differ from person to person. Schizophrenia is a family disease and can be devastating for all family members. Despite that, the support from relatives is crucial for the recovery. The stigmatization can make the illness worse and is also contributing to the fact that people with schizophrenia and their relatives are ashamed of the disease. Unlike the public prejudice that people with schizophrenia are violent and dangerous, researches have not been able to make such a conclusion based on mental illness alone. Further research needs to find ways to increase the knowledge of schizophrenia and decrease the stigmatization

MONTE CARLO-BASED DYNAMIC CALCULATIONS OF STATIONARY PERTURBATIONS

Capitalizing on some earlier work, this paper presents a novel Monte Carlo-based approach that allows estimating the neutron noise induced by stationary perturbations of macroscopic cross-sections in the frequency domain. This method relies on the prior computation using Monte Carlo of modified Green’s functions associated to the real part of the dynamic macroscopic cross-sections, mimicking equivalent subcritical problems driven by external neutron sources. Once such modified Green’s functions are estimated, the neutron noise induced by any type of perturbations can be recovered, by solving a linear algebra problem accounting for the interdependence between the real and imaginary parts of the governing balance equations. The newly derived method was demonstrated on a large homogeneous test system and on a small heterogeneous test system to provide results comparable to a diffusion-based solver specifically developed for neutron noise applications. The new method requires the specification by the user of the real part of the Fourier transform of the macroscopic cross-sections. This is accomplished using ACE-formatted cross-section files defined by the user. Beyond this input data preparation, no change to the Monte Carlo source code is necessary. This represents the main advantage of the proposed method as compared to similar efforts requiring extensive modifications to the Monte Carlo source code

MONTE CARLO-BASED DYNAMIC CALCULATIONS OF STATIONARY PERTURBATIONS

Capitalizing on some earlier work, this paper presents a novel Monte Carlo-based approach that allows estimating the neutron noise induced by stationary perturbations of macroscopic cross-sections in the frequency domain. This method relies on the prior computation using Monte Carlo of modified Green’s functions associated to the real part of the dynamic macroscopic cross-sections, mimicking equivalent subcritical problems driven by external neutron sources. Once such modified Green’s functions are estimated, the neutron noise induced by any type of perturbations can be recovered, by solving a linear algebra problem accounting for the interdependence between the real and imaginary parts of the governing balance equations. The newly derived method was demonstrated on a large homogeneous test system and on a small heterogeneous test system to provide results comparable to a diffusion-based solver specifically developed for neutron noise applications. The new method requires the specification by the user of the real part of the Fourier transform of the macroscopic cross-sections. This is accomplished using ACE-formatted cross-section files defined by the user. Beyond this input data preparation, no change to the Monte Carlo source code is necessary. This represents the main advantage of the proposed method as compared to similar efforts requiring extensive modifications to the Monte Carlo source code

Apoptosis and modulation of cell cycle control by bile acids in human leukemia T cells.

Depending on the nature of chemical structures, different bile acids exhibit distinct biological effects. Their therapeutic efficacy has been widely demonstrated in various liver diseases, suggesting that they might protect hepatocytes against commonmechanisms of liver damage. Although it has been shown to prevent apoptotic cell death in certain cell lines, bile acids significantly inhibited cell growth and induced apoptosis in cancer cells. To better understand the pharmacological potential of bile acids in cancer cells, we investigated and compared the effects of deoxycholic acid (DCA), ursodeoxycholic acid (UDCA), and their taurine-derivatives [taurodeoxycholic acid (TDCA) and tauroursodeoxycholic acid (TUDCA), respectively] on the induction of apoptosis and inhibition of cell proliferation of a human T leukemia cell line (Jurkat cells). All the bile acids tested induced a delay in cell cycle progression. Moreover, DCA markedly increased the fraction of apoptotic cells. The effects of TDCA, UDCA, and TUDCA were different from those observed for DCA. Their primary effect was the induction of necrosis. These distinctive features suggest that the hydrophobic properties of DCA play a role in its cytotoxic potential and indicate that it is possible to create new drugs useful for cancer therapy from bile acid derivatives as lead compounds