The Role of Hypoxia in Glioblastoma Radiotherapy Resistance.

Glioblastoma (GB) (grade IV astrocytoma) is the most malignant type of primary brain tumor with a 16 months median survival time following diagnosis. Despite increasing attention regarding the development of targeted therapies for GB that resulted in around 450 clinical trials currently undergoing, radiotherapy still remains the most clinically effective treatment for these patients. Nevertheless, radiotherapy resistance (radioresistance) is commonly observed in GB patients leading to tumor recurrence and eventually patient death.

Investigating Glioblastoma Response to Hypoxia.

Glioblastoma (GB) is the most common and deadly type of primary malignant brain tumor with an average patient survival of only 15-17 months. GBs typically have hypoxic regions associated with aggressiveness and chemoresistance. Using patient derived GB cells, we characterized how GB responds to hypoxia.

Osmotic stress, a proinflammatory signal in Caco-2 cells.

Hyper- (450 mOsm/l) and hypoosmotic exposure (150 mOsm/l) of Caco-2 cells, a human intestinal epithelial cell line, induced a twofold- and a fivefold increase in the production of IL-8, a constitutively expressed cytokine, respectively. This was observed both in the presence or in the absence of added proinflammatory cytokines and the stimulatory effect of osmotic stress was additive to that induced by the cytokines. Thus, IL-8 production appeared minimal around isoosmolarity, i.

Study of the B cell memory compartment in common variable immunodeficiency.

We evaluated the B cell memory pool among blood B cells from 20 patients with common variable immunodeficiency (CVID). CD27+ B cell number was normal or increased in 6 patients (with 95% CD27+ B cells in 1 patient) and decreased in 14 patients. In 13 or 15 patients studied, the CD27 molecule was detectable on less than 50% IgG or IgA B cells, indicating a defect in the maturation of these memory cells.

AMP-activated protein kinase counteracted the inhibitory effect of glucose on the phosphoenolpyruvate carboxykinase gene expression in rat hepatocytes.

The effect of AMP-activated protein kinase (AMPK) in the regulation of the phosphoenolpyruvate carboxykinase (PEPCK) gene expression was studied in isolated rat hepatocytes. Activation of AMPK by AICAR counteracted the inhibitory effect of glucose on the PEPCK gene expression, both at the mRNA and the transcriptional levels. It is proposed that a target for AMPK is involved in the inhibitory effect of glucose on PEPCK gene transcription.

Functional interactions between bile acids, all-trans retinoic acid, and 1,25-dihydroxy-vitamin D3 on monocytic differentiation and myeloblastin gene down-regulation in HL60 and THP-1 human leukemia cells.

Bile acids were shown previously to inhibit proliferation and to induce monocytic differentiation in HL60 human acute promyelocytic leukemia cells (A. Zimber et al., Int.

Protein synthesis is involved in the modulation of the level of the phosphoenolpyruvate carboxykinase mRNA by changes in cell volume in isolated rat hepatocytes.

The mechanism of action of hydration state was studied on phosphoenolpyruvate carboxykinase (PCK) gene expression in isolated rat hepatocytes. Hypoosmolarity decreased the level of the PCK mRNA after a lag period of about 60 min. The decreasing effect of hypoosmolarity was totally blocked by inhibitors of both protein synthesis and gene transcription.

Identification of a novel Ca2+-stimulated S6-kinase in rat liver.

Extracellular calcium addition transiently stimulated two S6 peptide kinase activities in isolated rat hepatocytes. Mono Q chromatography revealed that the activities eluting at 0.15 M NaCl and 0.

Glutamine inhibits the lowering effect of glucose on the level of phosphoenolpyruvate carboxykinase mRNA in isolated rat hepatocytes.

The expression of phosphoenolpyruvate carboxykinase (P-pyruvate CK) was shown to be decreased by hypoosmolarity and increased by glutamine in perfused liver from fed rats [Newsome, W. P., Warskulat, U.

Hypoosmolarity and glutamine increased the beta-actin gene transcription in isolated rat hepatocytes.

The mechanism of action of hydration state was studied on beta-actin gene expression in isolated hepatocytes. Results obtained with Northern blot analysis and run on transcription assays show that hypoosmolarity increased and hyperosmolarity decreased the beta-actin mRNA level through a corresponding modulation of the rate of the gene transcription. Glutamine, which is known to induce cell swelling, also increased the beta-actin mRNA level in a dose-dependent manner and induced a stimulation of the beta-actin gene transcription.

Effects of interferon-alpha and -gamma on B cell differentiation in macroglobulinemia.

We previously showed that clonal blood B cells from patients with macroglobulinemia spontaneously differentiate in vitro to plasma cells via an IL-6 autocrine pathway. Here we investigate whether interferon-alpha or -gamma would interfere with B cell differentiation either in patients with IgM gammopathy of undetermined significance (IgM-MGUS) or Waldenström's macroglobulinemia (WM). A 65% inhibition of in vitro B cell differentiation was noted in 8 of 10 patients in the presence of either interferon-alpha or -gamma.

Microcystin-LR induced an inhibition of protein synthesis in isolated rat hepatocytes.

The effect of microcystin-LR, an inhibitor of protein phosphatases PP1 and PP2A, was studied on protein synthesis by measuring the incorporation of labelled amino acid into protein in isolated rat hepatocytes. Microcystin-LR inhibited protein synthesis in the first minutes of the incubation period, and half-maximum effect was obtained at about 60 nM. Such an inhibition was also observed in the presence of different protein phosphatase inhibitors, i.

Inhibition of proliferation and induction of monocytic differentiation on HL60 human promyelocytic leukemia cells treated with bile acids in vitro.

We have tested the effect of several bile acids on the proliferation and differentiation of the HL60 human promyelocytic leukemia cell line in vitro. Deoxycholate, chenodeoxycholate and lithocholic acid caused dose-dependent inhibition of cell proliferation and induction of differentiation along the monocyte/macrophage pathway as determined by morphology, NBT test, non-specific esterase, and staining by monoclonal antibodies against specific cell-surface antigens. Optimal effects were obtained at 100, 75, and 60 microM of the 3 bile acids respectively.

Interaction of VIP, PACAP and related peptides in normal and leukemic human monocytes and macrophages.

The activation of the cAMP signaling pathway by vasoactive intestinal peptide (VIP), pituitary adenylate cyclase-activating peptide (PACAP) and related peptides was studied (i) in normal peripheral human monocytes and THP-1 leukemic human monocytes, (ii) in their derived macrophage counterparts respectively obtained after spontaneous differentiation or retinoic acid (RA) treatment, and (iii) in human bronchoalveolar macrophages. In THP-1 monocytes, PACAP increased basal adenylate cyclase activity 5.3-fold, with an affinity 50-times greater than that of VIP or helodermin (Ka = 3.

Inhibition of protein phosphatases activates glucose-6-phosphatase in isolated rat hepatocytes.

Incubation of hepatocytes in the presence of microcystin-LR, okadaic acid, calyculin A (inhibitors of protein phosphatases PP1 and PP2A) or microcystin-RR (a specific inhibitor of PP2A) activated glucose-6-phosphatase both in the supernatant and in intact or disrupted microsomes. Puromycin, an inhibitor of protein synthesis, totally suppressed this activating effect, suggesting the involvement of protein phosphatases in the regulation of glucose-6-phosphatase synthesis.

Glutamine is a good substrate for glycogen synthesis in isolated hepatocytes from 72 h-starved rats, but not from 24 h- or 48 h-starved rats.

In isolated hepatocytes from 24 h-starved rats, no glycogen synthesis was observed in the presence of glutamine. By contrast, glutamine was the best gluconeogenic substrate to induce glycogen synthesis in isolated hepatocytes from 72 h-starved rats. The effect of glutamine on glycogen synthesis was not accompanied by parallel changes in glucose or lactate production.

Metabolism of adenosine through adenosine kinase inhibits gluconeogenesis in isolated rat hepatocytes.

In isolated hepatocytes from fasted rats, 0.5 mM adenosine inhibited gluconeogenesis from glutamine, lactate and pyruvate. This inhibition was due to adenosine conversion through adenosine kinase.

Influence of 2-chloroadenosine on the nucleotide content of isolated rat hepatocytes.

2-Chloroadenosine is presumably a non-metabolizable analogue of adenosine; however, this compound induced an increase in the enzymatically measured nucleotide content of isolated rat hepatocytes. HPLC separation and spectral analysis of the peaks showed that this increase may be related to the formation of 2-chloro nucleotides and that the 2-chloro nucleotides appeared in the first minutes of the incubation period. These results demonstrate that 2-chloroadenosine may be metabolized by phosphorylation in rat liver cells.

Discrepancy between in vitro and in vivo passaged U-937 human leukemic cells: tumorigenicity and sensitivity to differentiating drugs.

The treatment of nude mice bearing tumors of transplanted human leukemic cells with drugs known to induce differentiation of the same leukemic cells in vitro does not always affect tumor yield, tumor cell differentiation or nude mice survival. We have transplanted human monoblastic leukemic cells of the U-937 cell line into newborn Swiss nu/nu mice. Priming with cyclophosphamide, followed by subcutaneous injections of at least 10 x 10(6) cells allowed us to obtain solid tumors.

A study of the efficacy of 5 alpha- and 5 beta-androstanes in chronic experimental aplastic anemia in mice.

The efficacy of in vivo administration of a 5 alpha-androstane and two 5 beta-androstanes (3 alpha and 3 beta) on CFU/GM and CFU/E mouse bone marrow stem cells was compared. The subjects were two groups of Swiss Webster mice: one normal group and one group in whom chronic aplastic anemia was induced by irradiation followed by mesenteric node lymphocyte grafting from C57/Bl donor mice. In normal animals, the two types of androgens (5 alpha and 5 beta) had the same efficacy, and the injection of 5 beta-androstane, before that of 5 alpha, significantly increased its efficacy.

Kinetic studies of the reaction mechanism of rat liver phosphoglycerate kinase in the direction of ADP utilization.

The kinetic properties of rat liver phosphoglycerate kinase were investigated in the forward direction of the reaction (utilization of ADP). The kinetic studies were performed in an assay system using combined hexokinase/glucose-6-phosphate dehydrogenase as an ATP trap. The Km values for Mg ADP1- and 1,3-diphospho-D-glycerate were approximately 0.

Two different in vitro growth patterns for erythroid precursors in 18 patients with pure erythrocytosis.

Growth patterns of marrow and blood erythroid progenitors were studied in 18 cases of pure erythrocytosis using different doses of erythropoietin. 8 cases demonstrated 'spontaneous' growth of CFU-E and blood BFU-E as observed in myeloproliferative disorders, but without an excess of circulating CFU-GM. 3 of these patients also had other symptoms of a pan-myelopathy.