D-2-Hydroxyglutarate does not mimic all the IDH mutation effects, in particular the reduced etoposide-triggered apoptosis mediated by an alteration in mitochondrial NADH

Somatic mutations in isocitrate dehydrogenase (IDH)-1 and -2 have recently been described in glioma. This mutation leads to a neomorphic enzymatic activity as the conversion of isocitrate to alpha ketoglutarate (αKG) is replaced by the conversion of αKG to D-2-hydroxyglutarate (D-2HG) with NADPH oxidation. It has been suggested that this oncometabolite D-2HG via inhibition of αKG-dioxygenases is involved in multiple functions such as epigenetic modifications or hypoxia responses. The present study is aimed at deciphering how the mutant IDH can affect cancer pathogenesis, in particular with respect to its associated oncometabolite D-2HG. We show that the overexpression of mutant IDH in glioma cells or treatment with D-2HG triggered an increase in cell proliferation. However, although mutant IDH reduced cell sensitivity to the apoptotic inducer etoposide, D-2HG exhibited no effect on apoptosis. Instead, we found that the apoptotic effect was mediated through the mitochondrial NADH pool reduction and could be inhibited by oxamate. These data show that besides D-2HG production, mutant IDH affects other crucial metabolite pools. These observations lead to a better understanding of the biology of IDH mutations in gliomas and their response to therapy.

Ammonia plasma concentration and prolonged infusion of remifentanil in patients with acute kidney injury

BACKGROUND

Glycine is an excipient of remifentanil and may induce side effects. To investigate glycine and ammonia concentration with the use of remifentanil in Intensive Care Unit patients with acute kidney injury (AKI) defined by a decrease in creatinine clearance above 50%.

METHODS

Prospective open-label cohort study in three surgical Intensive Care Units. Thirty-three patients with AKI and requiring sedation for at least 72 hours. Sedation with remifentanil and midazolam or propofol was adapted every six hours according to ATICE. Glycine and ammonia plasma concentrations were measured at H0 (start of infusion) and every 12 hours during a continuous intravenous 72 hours remifentanil infusion, and 24 hours after the end of the infusion. Clinical and biological glycine or ammonia toxicity were evaluated.

RESULTS

Fifteen patients required continuous veno-venous hemodiafiltration (CVVHDF). Glycine and ammonia plasma concentrations exceeded the normal value respectively for 11 (33%) and 15 (45%) patients before remifentanil infusion (H0). Accumulation of glycine or ammonia was observed neither for patients with or without CVVHDF. For patients without CVVHDF, the plasma ammonia concentration at the end of remifentanil infusion was significantly correlated with the creatinine clearance at H72 (P=0.03) and with the mean rate of remifentanil infusion (P=0.002). No side effect was reported.

CONCLUSION

Remifentanil was not associated with an accumulation of glycine or ammonia in patients with AKI. Plasma ammonia concentration was correlated with the mean rate of remifentanil and creatinine clearance. A 72-hours remifentanil infusion appeared safe for sedation of patients with AKI.

Paradoxical effect of lenalidomide on cytokine/growth factor profiles in multiple myeloma

Background:

Lenalidomide is an active immunomodulatory and antiproliferative agent in multiple myeloma. However, the molecular mechanisms driving these activities are not yet fully elucidated. Therefore, we investigated the modulation of the cytokine/growth factor patterns of myeloma cells under LEN treatment.

Methods:

Lenalidomide effect on myeloma cell proliferation was investigated in a myeloma cell line collection (n=23) by ³H-thymidine incorporation. Modulation of the cytokine/growth factor patterns of myeloma cells under LEN treatment was analysed by real-time quantitative PCR.

Results:

Lenalidomide inhibits the proliferation of two-thirds of myeloma cell lines independently of their genetic background. We demonstrated that LEN increased TNF-α and IL-8 inflammatory cytokines and insulin-like growth factor-1 (IGF-1) growth factor in both sensitive and resistant myeloma cells to LEN.

Conclusion:

Lenalidomide favours a uniform TNF-α and IL-8 inflammatory and IGF-1 secretory profile of myeloma cells, an observation that raises important questions for therapeutic approaches incorporating the agent.

Fas ligand expression in glioblastoma cell lines and primary astrocytic brain tumors

Fas/APO-1 (CD95) is a cell surface receptor that mediates apoptosis when it reacts with Fas ligand (FasL) or Fas antibody. We previously reported that Fas expression is predominantly induced in perinecrotic glioma cells, suggesting that Fas induction is associated with apoptosis and necrosis formation, a histological hallmark of glioblastomas. In this study, we assessed the expression of FasL in 10 glioblastoma cell lines and in 14 astrocytic brain tumors (three low-grade astrocytomas and 11 glioblastomas). Reverse transcriptase (RT)-PCR revealed that all glioblastoma cell lines and primary astrocytic brain tumors express FasL. Immunohistochemically, FasL was predominantly expressed on the plasma membrane of glioma cells. These results suggest that FasL expression is common in human astrocytic brain tumors and may cause apoptosis of glioma cells if Fas expression is induced.

Combination gene therapy: synergistic inhibition of human immunodeficiency virus Tat and Rev functions by a single RNA molecule

Current drug combinations can achieve long-term suppression of HIV replication in infected individuals. Unfortunately, complicated dosing schedules and high toxicity make long-term compliance with drug regimens difficult for most patients. Gene therapy may provide a permanent solution for HIV disease by generating cells genetically resistant to virus replication. As with the highly active antiretroviral therapies, genetic drugs must have strong antiviral potency and the ability to prevent the emergence of escape mutants. We have constructed antiviral genes containing unique combinations of Tat- and Rev-binding decoys. The new antiviral molecules are chimeric TAR-RRE RNAs that are expressed only in HIV infected cells in a Tat-regulated manner. One RNA molecule competes for both Tat and Rev binding, and thus blocks the activation and the expression of all viral genes. The two functional Tat- and Rev-binding domains exhibit the highest synergy at the lowest concentration. Conservative quantitative estimates of this synergistic effect were I = 0.24 at 50% inhibition, in terms of the Berenbaum "interaction index," indicating that the combined construct was approximately fourfold more potent than would be predicted on the basis of additive effects. The possibility of HIV escape from this inhibition is unlikely, because it requires simultaneous mutation of TAR and RRE in a manner in which both Tat and Rev preserve their respective functions. TAR-RRE combination decoys represent the first example of mathematically proven synergistic antiviral activity between two domains of the same molecule.

PTEN (MMAC1) mutations are frequent in primary glioblastomas (de novo) but not in secondary glioblastomas

Loss of heterozygosity (LOH) on chromosome 10 is the most frequent genetic alteration associated with the evolution of malignant astrocytic tumors and it may involve several loci. The tumor suppressor gene PTEN (MMAC1) on chromosome 10q23 is mutated in approximately 30% of glioblastomas (WHO Grade IV). In this study, we assessed the frequency of PTEN mutations in primary glioblastomas, which developed clinically de novo, and in secondary glioblastomas, which evolved from low-grade (WHO Grade II) or anaplastic astrocytomas (WHO Grade III). Nine of 28 (32%) primary glioblastomas contained a PTEN mutation and an additional case showed a homozygous PTEN deletion. This indicates that after overexpression/amplification of the EGF receptor, loss of PTEN function is the most common alteration in primary glioblastomas. In this series, 5 of 28 (18%) primary glioblastomas showed both a PTEN mutation and EGFR amplification. In contrast, only 1 of 25 (4%) secondary glioblastomas contained a PTEN mutation, and none of them showed a homozygous PTEN deletion. The secondary glioblastoma with a PTEN mutation developed from an anaplastic astrocytoma that already carried the mutation. The observation that secondary glioblastomas have a p53 mutation as a genetic hallmark but rarely contain a PTEN mutation supports the concept that primary and secondary glioblastomas develop differently on a genetic level.

p53 and PTEN gene mutations in gemistocytic astrocytomas

The gemistocytic astrocytoma is a histological variant of diffuse astrocytomas and is characterised by the presence of large, GFAP-expressing neoplastic astrocytes (gemistocytes) and a tendency towards rapid progression to glioblastoma. In this study, we analyzed 28 gemistocytic astrocytomas (mean fraction of gemistocytes, 35.0+/-9.9%) for mutations in the p53 and PTEN (MMAC1) tumour suppressor genes. Single strand conformation polymorphism (SSCP), followed by direct DNA sequencing of p53 exons 5-8, revealed a mutation in 23 of 28 (82%) cases. Regional analysis of four tumours revealed identical p53 mutations in gemistocytic and fibrillary tumour areas. In contrast, none of 15 gemistocytic astrocytomas (WHO Grade II) and only two of 11 (18%) anaplastic gemistocytic astrocytomas (WHO Grade III) contained a PTEN mutation. Of these, one was a 1 bp deletion in codon 345 and the other a 1 bp insertion in intron 4. Differential PCR did not reveal homozygous PTEN deletion in any of the tumours analysed. These results indicate that p53 mutations are a genetic hallmark of gemistocytic astrocytomas, whilst PTEN mutations are absent in low-grade and rare in anaplastic gemistocytic astrocytomas.

Up-regulation of Fas (APO-1/CD95) ligand and down-regulation of Fas expression in human esophageal cancer

Fas (APO-1/CD95) is a cell surface receptor that mediates apoptosis when it reacts with Fas ligand (FasL) or Fas antibody. In this study, we analyzed Fas and FasL expression in normal esophageal mucosa and esophageal squamous cell carcinomas. Reverse transcriptase-PCR revealed that Fas, soluble Fas, and FasL were expressed in all eight esophageal squamous carcinoma cell lines analyzed. Furthermore, it was demonstrated that FasL expressed in esophageal carcinoma cells is functional because coculture experiments using FasL-expressing TE-15 esophageal carcinoma cells resulted in apoptosis of Jurkat T leukemia cells, which are sensitive to Fas-mediated apoptosis. Immunohistochemistry of Fas and FasL showed that they are constitutively expressed in normal esophageal mucosa, FasL being predominantly in the basal and suprabasal layers, whereas Fas is in more differentiated layers, i.e., rows of polyhedral cells of the intermediate layers and squamous cells forming the outer layers. In 18 of 19 invasive esophageal squamous cell carcinomas, FasL expression was found in >50% of tumor cells. In contrast, most tumors (15 of 19, 79%) either showed no Fas expression or showed expression in <5% of tumor cells. These alterations were already detected in dysplasia and carcinoma in situ. These results suggest that up-regulation of FasL and down-regulation of Fas expression are early and frequent events associated with the evolution of esophageal squamous cell carcinomas.

Necrogenesis and Fas/APO-1 (CD95) expression in primary (de novo) and secondary glioblastomas

Glioblastomas may develop rapidly without clinical and histopathological evidence of a less malignant precursor lesion (de novo or primary glioblastoma) or through progression from low-grade or anaplastic astrocytoma (secondary glioblastoma). Primary glioblastomas typically show overexpression of EGFR, but rarely p53 mutations, while secondary glioblastomas frequently carry a p53 mutation, but usually lack overexpression of EGFR, suggesting that these glioblastoma subtypes develop through distinct genetic pathways. In the present study, we assessed the expression of Fas/APO-1 (CD95), an apoptosis-mediating cell membrane protein, and its relation to necrosis phenotype in primary and secondary glioblastomas. Large areas of ischemic necroses were observed in all 18 primary glioblastomas, but were significantly less frequent in secondary glioblastomas (10 of 19, 53%; p = 0.0004). Fas expression was predominantly observed in glioma cells surrounding large areas of necrosis and was thus significantly more frequent in primary glioblastomas (18 of 18, 100%) than in secondary glioblastomas (4 of 19, 21%; p < 0.0001), suggesting that these clinically and genetically defined subtypes of glioblastoma differ in the extent and mechanism of necrogenesis. Necrosis and microvascular proliferation are histologic hallmarks of the glioblastoma. Following incubation of glioblastoma cell lines under hypoxic/anoxic conditions for 24-48 hours, Fas mRNA levels remained unchanged, whereas VEGF expression was markedly upregulated. This suggests that in contrast to VEGF Fas expression is not induced by ischemia/hypoxia. Analysis of Fas mRNA levels in a glioblastoma cell line containing a p53 mutation and an inducible wild-type p53 gene showed little difference under induced and noninduced conditions, suggesting that in glioblastomas, Fas expression is not directly linked to the p53 status.

Reduced expression of the P2 form of the gap junction protein connexin43 in malignant meningiomas

Neoplastic transformation is often associated with aberrant gap junctional intercellular communication. We assessed mutations and expression of the connexin43 (Cx43) gene in 49 intracranial meningiomas. SSCP analyses followed by direct DNA sequencing showed GCG-->GTG (Ala-->Val) transition mutation in codon 253 of the cytoplasmic carboxyl terminal of the Cx43 gene in 1 of 31 (3%) benign meningiomas and 1 of 14 (7%) anaplastic meningiomas. The same base change was present in normal tissue from these patients and also in 4 of 80 (5%) DNA samples extracted from lymphocytes of healthy Europeans, suggesting that this constitutes a newly identified Cx43 polymorphism. Western blot analyses showed expression of phosphorylated P1 (45 kD) and P2 (47 kD) Cx43 as well as the unphosphorylated form (42 kD) in 11 of 14 (79%) benign meningiomas. In contrast, the P2 form was not detectable in the majority (7 of 9; 78%) of atypical and anaplastic meningiomas. Since the presence of the P2 form is often associated with optimal function of the Cx43, these results suggest that loss or impaired gap junctional cell to cell communication may be associated with meningiomas displaying more rapid growth and a less favorable prognosis.

Ischaemia-induced expression of bFGF in normal skeletal muscle: a potential paracrine mechanism for mediating angiogenesis in ischaemic skeletal muscle

To test the hypothesis that induction of endogenous bFGF can lead to angiogenesis in ischaemic skeletal muscle, we studied the expression of bFGF after transposition of a well-vascularized muscle flap onto an ischaemic hindlimb in the rabbit. The results indicated a marked induction of bFGF mRNA throughout the myoblasts of the well-perfused muscle flap but not the myoblasts of the ischaemic muscle. bFGF protein was detected in the muscle flap, particularly in the myoblasts located closest to a newly formed, adjacent interface, and in the interface itself. In contrast, bFGF expression was not induced after transposition of a well-perfused muscle flap onto healthy muscle tissue. These data provide evidence that the juxtaposition of ischaemic skeletal muscle with healthy mesenchymal tissue triggers an increased expression of bFGF in the myoblasts of the well-perfused muscle. This paracrine induction of bFGF, in turn, leads to increased angiogenesis and regeneration of the ischaemic skeletal muscle.

Isolation and analysis of novel human melanocyte-specific cDNA clones

Human melanoma represents a neurocrest-derived malignancy, occurring in 10% of cases within the setting of a familial predisposition and in 90% of cases with sporadic onset. It is estimated that more than 85% of familial melanomas and about 40% of sporadic melanomas arise from melanocytic precursor lesions. In an attempt to isolate genes that may play a role in human melanocytic progression, we applied subtractive cDNA hybridization, involving repeated rounds of subtraction. This was followed by amplification of the remaining enriched cDNAs, which led to the isolation of several human melanocyte-enriched cDNA clones. Evidence is provided suggesting that these melanocyte-enriched cDNA probes may be derived from novel genes whose expression is significantly up-regulated in normal human melanocytes compared to early and advanced-stage human melanomas.

Retinoid acid supports granulocytic but not erythroid differentiation of myeloid progenitors in normal bone marrow cells

In the new context of the use of retinoic acid (RA) therapy as an inducer of leukemic differentiation and a selective inhibitor of human myeloid leukemia cell growth, we undertook to explore the potential physiological role of retinoids on the proliferation and differentiation of normal bone marrow myeloid progenitors. The effects of continuous exposure of all-trans-RA, its naturally occurring isomer, 13-cis-RA, and its metabolite 4-oxo-all-trans-RA were studied on the growth of normal human bone marrow cells in soft agar, directly and after liquid culture. Retinoids enhanced the total number of granulocytic colony and macrocluster formation in the presence of exogenous colony-stimulating factor (n = 9). Dose-response curve were bell-shaped, with a maximal increment between concentration of 0.5 and 0.05 nM. In all cases, a concomitant decrease of macrophagic colonies was noted. The positive effect on granulocytic colony formation was observed with each of the retinoids tested (all-trans, 13-cis and 4-oxo-all-trans) (n = 5). On erythroid colony formation, all-trans-RA had the opposite effect. Constant suppression of CFU-E and BFU-E colony formation and coloring was observed in a dose-related fashion from 0.1 to 10 microM (n = 5). Thus, in granulocytic, as in erythroid colony formation, retinoids affected both proliferation and differentiation parameters. However, after short-term suspension culture in the presence of all-trans-RA, an increase of both CFU-GM and BFU-E colonies, was observed. These results suggest a specific effect of retinoids on late myeloid precursors and places retinoids as possible candidates for enhancement of normal granulocytic differentiation.

Inhibition of phospholipase D by agents that inhibit cell growth

The phospholipases are an important class of enzymes for growth factor and oncogene intracellular signalling. The anti-tumor drug suramin was found to inhibit phosphatidylcholine hydrolysis and trans-phosphatidylation by solubilized rat brain phospholipase D (PLD) with an IC50 of 15 microM. An azo analogue of suramin, which is a considerably more potent inhibitor of phosphatidylinositol phospholipase C (PIPLC) than suramin, inhibited PLD with and IC50 of 58 microM. D-609, a xanthogenate compound with in vitro antitumor activity, inhibited PLD with an IC50 of 820 microM. The cytotoxic aminosteroid compound U-73, 122 was a weaker inhibitor of PLD with an IC50 of 78 microM. However, U-73, 122 was a more potent inhibitor of PLD in fibroblast membranes with an IC50 of 25 microM, while suramin was less active with an IC50 of 4.2 mM. The antitumor ether lipid drug ET-18-OCH3 did not inhibit solubilized or membrane PLD although it is a potent inhibitor of PIPLC. The results of the study show that the compounds tested have different abilities to inhibit PIPLC and PLD. Access of hydrophilic drugs to membrane PLD may be a limiting factor to their inhibitory activity.

In vivo study of vinorelbine associations with cisplatin, 5-fluorouracil or actinomycin D relative to a non-small-cell lung carcinoma (NSCLCN6-L16)

Vinorelbine (NavelbineR) is a new antitumor agent chemically related to the Vinca alkaloid group, but differentiated by its in vivo activity relative to non-small-cell lung carcinoma (NSCLC). Studies in the NSCLC-bearing nude mouse of vinorelbine associations with drugs currently used clinically in phase III (cisplatin, 5-fluorouracil and actinomycin D) showed that such associations are ineffective or even of negative value and that it would be preferable to use vinorelbine alone in a single dose at the maximum tolerated concentration.

Selective inhibition of phosphatidylinositol phospholipase C by cytotoxic ether lipid analogues

The ether lipid analogue 1-octadecyl-2-methyl-rac-glycero-3-phosphocholine (ET-18-OCH3) has been shown to be a direct inhibitor of Swiss 3T3 fibroblast and BG1 ovarian adenocarcinoma cell cytosolic phosphoinositide selective phospholipase C (PIPLC) using [3H]-phosphatidylinositol-(4, 5)-bisphosphate ([3H]PIP2) as the substrate. The inhibition occurred when ET-18-OCH3 was incorporated into the [3H]PIP2 substrate micelles, with 50% inhibition (IC50) occurring at a ET-18-OCH3: [3H]PIP2 ratio of 0.04, or an assay concentration of 0.4 microM, and when ET-18-OCH3 was added directly to the incubation, with an IC50 of 9.6 microM. Lipid prepared from cells exposed to cytotoxic concentrations of ET-18-OCH3 for 18 h also inhibited PIPLC with an IC50 less than 1 microM. The noncytotoxic analogue 1-O-alkyl-2-hydroxy-sn-glycero-3-phosphocholine inhibited PIPLC when incorporated into the [3H]PIP2 substrate micelles, but lipid from cells grown with 5 microM 1-O-alkyl-2-hydroxy-sn-glycero-3-phosphocholine did not inhibit PIPLC. BG1 cells, which were more sensitive than Swiss 3T3 fibroblasts to growth inhibition by ET-18-OCH3, had a cytosolic PIPLC activity one-third that of Swiss 3T3 cells. NIH 3T3 cells exhibited the same sensitivity to growth inhibition by ET-18-OCH3 as Swiss 3T3 cells and had a similar level of PIPLC. v-sis NIH 3T3 cells were relatively resistant (greater than 3-fold) to growth inhibition by ET-18-OCH3 and had a cytosolic PIPLC activity more than twice that of the wild type cells. ET-18-OCH3 was a weak inhibitor, IC50 greater than 100 microM, of phospholipase D activity in NIH 3T3 cell membranes. In intact NIH 3T3 cells ET-18-OCH3 at cytotoxic concentrations did not inhibit phospholipase D or phosphatidylcholine-selective phospholipase C activity. The results show that the ether lipid analogues at cytotoxic concentrations are selective inhibitors of PIPLC and that the inhibition of PIPLC may be related to the growth inhibitory activity of the ether lipid analogues.

Inhibition of growth factor binding, Ca2+ signaling and cell growth by polysulfonated azo dyes related to the antitumor agent suramin

The ability of the polysulfonated antitumor drug suramin and six related polysulfonated azo dyes to inhibit the cell growth, platelet-derived growth factor (PDGF)-receptor binding, and intracellular Ca2+ signaling of Swiss 3T3 fibroblasts was studied. Some of the azo dyes were more potent inhibitors of PDGF binding than was suramin. The concentration giving 50% inhibition (IC50) of PDGF binding was 0.5 microM for the most potent azo dye as compared with 10 microM for suramin. The azo dyes were generally more potent inhibitors of nonmitochondrial Ca2+ uptake and of inositol(1,4,5)trisphosphate-mediated Ca2+ release in permeabilized Swiss 3T3 cells than was suramin, and they were more potent inhibitors of PDGF-induced Ca2+ signaling in intact Swiss 3T3 cells. The azo dyes were only as effective as or less effective than suramin in inhibiting the growth of Swiss 3T3 cells, with IC50 values of between 74 and 361 microM being noted for the dyes as compared with 70 microM for suramin. The difference between the growth-inhibitory activity of the azo dyes and that of suramin could not be explained by metabolism of the compounds, which was not detectable in either Swiss 3T3 cells or human liver slice preparations. The results suggest that suramin and some of the azo dyes have actions on cell growth in addition to inhibition of growth factor binding and of Ca2+ signaling.

Study of in vitro drug sensitivity on a newly established cell line from a primary bronchial epidermoid carcinoma of human origin (NSCLCN6)

We studied a cell line established from a primary non-small-cell lung cancer (non-SCLC) of human origin and characterized by midly differentiated epidermoid carcinoma, a human karyotype and keratin expression. Doubling time was about 48 h in vitro and 12 days when transplanted into nude mice. In vitro, this cell line was mainly sensitive to dactinomycin and mitotic poisons such as Vinca alkaloids. Most chemotherapeutic drugs proved ineffective. Our findings are comparable to previous results in patients who showed 30% objective response and less than 5% complete response regardless of the therapeutic associations used against non-SCLC. Our line would also seem to provide a good model for studying new potentially antitumor substances.

Study of the heterogeneity of a human non-small cell bronchopulmonary epidermoid primary carcinoma: determination of the DNA content of NSCLCN6L2 cells and of cloned sub-populations

A continuous cell line, NSCLCN6L2, was established in vitro from a human bronchopulmonary epidermoid carcinoma and then cloned on agar gel and by selective media. The DNA content of each sub-population was compared with that of the parent line by flow cytometry. This study showed the heterogeneity of the NSCLCN6L2 line and the possibility of selection by cloning distinct ploidy sub-populations (group 1: diploid lines; group 2: hypotetraploid lines; group 3: a diploid and tetraploid line); it also allowed the time-course of the evolving lines to be followed. Correlation of these results with other properties of the different sub-populations will provide a better understanding of their biological behavior, particularly of their chemosensitivity.