Control of intestinal inflammation by glycosylation-dependent lectin-driven immunoregulatory circuits

Diverse immunoregulatory circuits operate to preserve intestinal homeostasis and prevent inflammation. Galectin-1 (Gal1), a β-galactoside-binding protein, promotes homeostasis by reprogramming innate and adaptive immunity. Here, we identify a glycosylation-dependent "on-off" circuit driven by Gal1 and its glycosylated ligands that controls intestinal immunopathology by targeting activated CD8⁺ T cells and shaping the cytokine profile. In patients with inflammatory bowel disease (IBD), augmented Gal1 was associated with dysregulated expression of core 2 β6-N-acetylglucosaminyltransferase 1 (C2GNT1) and α(2,6)-sialyltransferase 1 (ST6GAL1), glycosyltransferases responsible for creating or masking Gal1 ligands. Mice lacking Gal1 exhibited exacerbated colitis and augmented mucosal CD8⁺ T cell activation in response to 2,4,6-trinitrobenzenesulfonic acid; this phenotype was partially ameliorated by treatment with recombinant Gal1. While C2gnt1^-/- mice exhibited aggravated colitis, St6gal1^-/- mice showed attenuated inflammation. These effects were associated with intrinsic T cell glycosylation. Thus, Gal1 and its glycosylated ligands act to preserve intestinal homeostasis by recalibrating T cell immunity.

Proteomic screening identifies calreticulin as a miR-27a direct target repressing MHC class I cell surface exposure in colorectal cancer

Impairment of the immune response and aberrant expression of microRNAs are emerging hallmarks of tumour initiation/progression, in addition to driver gene mutations and epigenetic modifications. We performed a preliminary survey of independent adenoma and colorectal cancer (CRC) miRnoma data sets and, among the most dysregulated miRNAs, we selected miR-27a and disclosed that it is already upregulated in adenoma and further increases during the evolution to adenocarcinoma. To identify novel genes and pathways regulated by this miRNA, we employed a differential 2DE-DIGE proteome analysis. We showed that miR-27a modulates a group of proteins involved in MHC class I cell surface exposure and, mechanistically, demonstrated that calreticulin is a miR-27a direct target responsible for most downstream effects in epistasis experiments. In vitro miR-27a affected cell proliferation and angiogenesis; mouse xenografts of human CRC cell lines expressing different miR-27a levels confirmed the protein variations and recapitulated the cell growth and apoptosis effects. In vivo miR-27a inversely correlated with MHC class I molecules and calreticulin expression, CD8⁺ T cells infiltration and cytotoxic activity (LAMP-1 exposure and perforin release). Tumours with high miR-27a, low calreticulin and CD8⁺ T cells' infiltration were associated with distant metastasis and poor prognosis. Our data demonstrate that miR-27a acts as an oncomiRNA, represses MHC class I expression through calreticulin downregulation and affects tumour progression. These results may pave the way for better diagnosis, patient stratification and novel therapeutic approaches.

The miR-27a-calreticulin axis affects drug-induced immunogenic cell death in human colorectal cancer cells

Immunogenic cell death (ICD) evoked by chemotherapeutic agents implies emission of selected damage-associated molecular patterns (DAMP) such as cell surface exposure of calreticulin, secretion of ATP and HMGB1. We sought to verify whether miR-27a is implicated in ICD, having demonstrated that it directly targets calreticulin. To this goal, we exposed colorectal cancer cell lines, genetically modified to express high or low miR-27a levels, to two bona fide ICD inducers (mitoxantrone and oxaliplatin). Low miR-27a-expressing cells displayed more ecto-calreticulin on the cell surface and increased ATP and HMGB1 secretion than high miR-27a-expressing ones in time-course experiments upon drug exposure. A calreticulin target protector counteracted the miR-27a effects while specific siRNAs mimicked them, confirming the results reported. In addition, miR-27a negatively influenced the PERK-mediated route and the late PI3K-dependent secretory step of the unfolded protein response to endoplasmic reticulum stress, suggesting that miR-27a modulates the entire ICD program. Interestingly, upon chemotherapeutic exposure, low miR-27a levels associated with an earlier and stronger induction of apoptosis and with morphological and molecular features of autophagy. Remarkably, in ex vivo setting, under the same chemotherapeutic induction, the conditioned media from high miR-27a-expressing cells impeded dendritic cell maturation while increased the secretion of specific cytokines (interleukin (IL)-4, IL-6, IL-8) and negatively influenced CD4⁺ T-cell interferon γ production and proliferation, all markers of a tumor immunoevasion strategy. In conclusion, we provide the first evidence that miR-27a impairs the cell response to drug-induced ICD through the regulatory axis with calreticulin.

Reprogramming cancer cells in endocrine-related tumors: open issues

Reprogramming technologies have been developed to revert somatic differentiated cells into pluripotent stem cells that can be differentiated into different lineages potentially useful in stem cell therapy. Reprogramming methods have been progressively refined to increase their efficiency, to obtain a cell population suitable for differentiation, and to eliminate viral plasmid which could be responsible for many unwanted side-effects when used in personalized medicine. All these methods are aimed to introduce into the cell genes or mRNAs encoding a set of four transcription factors (OCT- 4, SOX-2, KLF-4 and c-MYC) or a set of three lincRNAs (large intragenic non-coding RNAs) acting downstream of the reprogramming transcription factors OCT-4, SOX-2 and NANOG. Translational clinical applications in human pathologies and in developmental, repair and cancer biology have been numerous. Cancer cells can be, at least in principle, reprogrammed into a normal phenotype. This is a recently raised issue, rapidly advancing in many human tumors, especially endocrine-related cancers, such as breast, prostate and ovarian ca. The present review aims to describe basic phenomena observed in reprogramming tumor cells and solid tumors and to discuss their meaning in human hormone-related cancers. We will also discuss the fact that some of the targeted transcription factors are "normally" activated in a number of physiological processes, such as morphogenesis, hypoxia and wound healing, suggesting an in vivo role of reprogramming for development and homeostasis. Finally, we will review concerns and warnings raised for in vivo reprogramming of human tumors and for the use of induced pluripotent stem cells (iPSCs) in human therapy.

Panobinostat synergizes with zoledronic acid in prostate cancer and multiple myeloma models by increasing ROS and modulating mevalonate and p38-MAPK pathways

Patients with advanced prostate cancer (PCa) and multiple myeloma (MM) have limited long-term responses to available therapies. The histone deacetylase inhibitor panobinostat has shown significant preclinical and clinical anticancer activity in both hematological and solid malignancies and is currently in phase III trials for relapsed MM. Bisphosphonates (BPs), such as zoledronic acid (ZOL), inhibit osteoclast-mediated bone resorption and are indicated for the treatment of bone metastasis. BPs, including ZOL, have also shown anticancer activity in several preclinical and clinical studies. In the present report, we found a potent synergistic antiproliferative effect of panobinostat/ZOL treatment in three PCa and three MM cell lines as well as in a PCa ZOL-resistant subline, independently of p53/KRAS status, androgen dependency, or the schedule of administration. The synergistic effect was also observed in an anchorage-independent agar assay in both ZOL-sensitive and ZOL-resistant cells and was confirmed in vivo in a PCa xenograft model. The co-administration of the antioxidant N-acetyl-L-cysteine blocked the increased reactive oxygen species generation and apoptosis observed in the combination setting compared with control or single-agent treatments, suggesting that oxidative injury plays a functional role in the synergism. Proapoptotic synergy was also partially antagonized by the addition of geranyl-geraniol, which bypasses the inhibition of farnesylpyrophosphate synthase by ZOL in the mevalonate pathway, supporting the involvement of this pathway in the synergy. Finally, at the molecular level, the inhibition of basal and ZOL-induced activation of p38-MAPK by panobinostat in sensitive and ZOL-resistant cells and in tumor xenografts could explain, at least in part, the observed synergism.

Treatment of glaucomatous patients by means of food supplement to reduce the ocular discomfort: a double blind randomized trial

BACKGROUND AND AIM

Chronic use of multi-dose eye drops containing preservatives, such as it may happen in patients affected by primary open angle glaucoma, often results in a damage of the ocular surface due to the inherent toxicity of preservatives, that with time may lead to a lacrimal dysfunction syndrome and eye dryness.

PATIENTS AND METHODS

This double blind, randomized, pilot study was conducted on 38 glaucomatous patients suffering from dry eye induced by long-term use of eye drops preserved with BAK.

RESULTS

Treatment of these patients with a food supplement containing an association of forskolin, rutin and vitamins B1 and B2 for 30 days increased significantly their OPI values and improved the symptoms of dry eye with respect to a placebo-treated control group.

CONCLUSIONS

The association of forskolin, rutin and vitamins B1 and B2 appears to be protective for the ocular surface, contributing to restore a normal equilibrium of the tear film in those subjects in which toxic agents such as BAK had determined alterations of its homeostasis.

Influence of age and physical exercise on sirtuin activity in humans

Sirtuins are NAD+-dependent lysine deacetylases. Sirtuins acquired worldwide attention because of their ability to increase yeast, flies, worms and mice lifespan. Recently, this assumption has been challenged. However, their beneficial role on the quality of ageing is widely accepted. In this work we aimed to study how and if sirtuins expression and activity levels varies in function of age and, in the case of young subjects, of exercise. Fifteen blood donors of different ages and fifteen athletes of the Italian rowing male team were enrolled and peripheral blood mononuclear cells (PBMCs) isolated from blood samples. Our results show that sirtuins deacetylases activity measured in PBMCs increases from 18 to 40 years of age and then decreases during the following 20 years. Moreover, physical exercise in professional athletes can upregulate sirtuin activity. Thus, for the first time in humans, we demonstrate that sirtuin activity is a function of age and can be altered through physical exercise.

An in vitro study of the sub-cellular distribution of nicotinic receptors

Nicotinic and serotoninergic 5HT3 receptors share important sequence identities except for their cytoplasmic loop. Both ends of this loop display conserved 3D helical structures with distinct primary sequences. We decided to check whether these two helices named F and G play a role in the sub-cellular distribution of different nicotinic receptors. We systematically exchanged each helix with the equivalent sequence of neuronal nicotinic and alpha4, beta2 and alpha7 subunits in the functional chimeric alpha7-5HT3 receptor used as a model system. The new chimeras were expressed in vitro in polarized epithelial cells from pig kidney. We quantified synthesis and export of the receptors to the cell surface by measuring alpha-bungarotoxin binding sites. Immunogold labelling was used, at the electron microscope level, to determine the amount of each chimera present at either domain, apical and/or basolateral, of these cells. We noticed that in epithelial cells the majority of alpha-bungarotoxin binding sites remained sequestered in the cytoplasm as already observed in neurons in vivo. The majority of the pentamers present at the cell surface were located at the apical domain. Our results suggest that helix F and G differently regulate assembly and export to the cell surface of alpha-bungarotoxin binding receptors.

Amphipols from A to Z

Amphipols (APols) are short amphipathic polymers that can substitute for detergents to keep integral membrane proteins (MPs) water soluble. In this review, we discuss their structure and solution behavior; the way they associate with MPs; and the structure, dynamics, and solution properties of the resulting complexes. All MPs tested to date form water-soluble complexes with APols, and their biochemical stability is in general greatly improved compared with MPs in detergent solutions. The functionality and ligand-binding properties of APol-trapped MPs are reviewed, and the mechanisms by which APols stabilize MPs are discussed. Applications of APols include MP folding and cell-free synthesis, structural studies by NMR, electron microscopy and X-ray diffraction, APol-mediated immobilization of MPs onto solid supports, proteomics, delivery of MPs to preexisting membranes, and vaccine formulation.

Protection Against Reactive Oxygen Species Injuries in Rat Isolated Perfused Hearts: Effect of LPBNAH, a New Amphiphilic Spin-Trap Derived from PBN

Numerous strategies have been designed to protect the myocardium against reactive oxygen species (ROS). The present study was designed to test wether LPBNAH, a new amphiphilic spin-trap derived from PBN is able to protect isolated perfused rat hearts against ROS injuries. Following total glola ischemia (30 min), hearts were reperfused in the presence or not of LPBNAH (10 micromol/l), and left ventricular function was continuously monitored. The addition of LPBNAH led to a significant recovery in left ventricular developped pressure (LVDevP, control: 16.5+/- 7.5, p < 0.05). To conclude, the present results strongly suggest that the modification of previous wellknown molecules in order to facilitate their access to intracellular site of ROS production might be of interest to limit oxidative stresses.

In vitro and in vivo evaluations of THAM derived telomers bearing RGD and Ara-C for tumour neovasculature targeting

As an approach to the development of specific drug delivery systems, a new class of low macromolecular carriers called 'telomers' endowed with an antitumour agent, such as arabinofuranosylcytosine (Ara-C), RGDSK peptidic sequences, as tumour targeting moieties, and tyrosine groups labelled with 125I atoms allowing the in vivo scintigraphic follow up, were synthesized. Their tumour targeting ability was assessed in vivo in mice bearing a murine B16 melanoma. The biological results showed that the presence of RGDSK sequences onto the macromolecules leads to the selective targeting and the accumulation of telomers within the vascularized zone of the tumour. Moreover, such compounds exhibited in vitro a better IC(50) (0.015 muM) than pure Ara-C and in vivo an oncostatic index higher than 160%.

Synthesis and antioxidant efficiency of a new amphiphilic spin-trap derived from PBN and lipoic acid

The synthesis of a new amphiphilic antioxidant called PBNLP and derived from both alpha-phenyl-N-tert-butyl nitrone (PBN) and lipoic acid was described. Grafting a lactobionamide moiety onto the aromatic group of the PBN provided the water solubility of this compound. In vitro preliminary biological evaluations of its antioxidant capacity were performed using the KRL biological test based on free radical-induced hemolysis. The PBNLP induces a protection of erythrocytes against exogenous free radicals higher than that measured with lipoic acid or PBN alone or with lipoic acid or PBN derivatives in admixtures.

Amphipols: polymeric surfactants for membrane biology research

Membrane proteins classically are handled in aqueous solutions as complexes with detergents. The dissociating character of detergents, combined with the need to maintain an excess of them, frequently results in more or less rapid inactivation of the protein under study. Over the past few years, we have endeavored to develop a novel family of surfactants, dubbed amphipols (APs). APs are amphiphilic polymers that bind to the transmembrane surface of the protein in a noncovalent but, in the absence of a competing surfactant, quasi-irreversible manner. Membrane proteins complexed by APs are in their native state, stable, and they remain water-soluble in the absence of detergent or free APs. An update is presented of the current knowledge about these compounds and their demonstrated or putative uses in membrane biology.

Induction of apoptosis in skeletal tissues: phosphate-mediated chick chondrocyte apoptosis is calcium dependent

In an earlier study, we have shown that Pi induced apoptosis of terminally differentiated hypertrophic chondrocytes. To ascertain whether Ca2+ modulates Pi-induced cell death, we asked the following two questions: First, can we prevent Pi-induced apoptosis by removing Ca2+ from the culture medium; alternatively, can we potentiate cell death by increasing the Ca2+ concentration? Second, can we inhibit chondrocyte apoptosis by blocking Pi transport? We also explored the mechanism of apoptosis by evaluating mitochondrial activity and reactive oxygen species (ROS) generation in cells treated with the ion pair. We noted that EDTA and EGTA blocked Pi-induced apoptosis in a dose-dependent manner. While high levels of Ca2+ alone had little effect on chondrocyte viability, the cation enhanced Pi-dependent cell death and greatly increased Pi uptake. When Pi transport was blocked, there was complete inhibition of cell killing. The process of cell death was characterized by mitochondrial hyperpolarization; two hours following apoptogen treatment, there was a significant decrease in the mitochondrial membrane potential. Coincident with the changes in mitochondrial function, there was an increase in intracellular Ca2+ that was maintained throughout the experimental period. A raised Ca2+ signal was observed in blebs at the cell membrane. Finally, we noted that, 75 minutes after treatment with the ion pair, there was a six-fold elevation in ROS levels. This increase declined to baseline values after three hours. Based on these observations, we suggest that, at the cartilage mineralization front, an elevation in local environmental Ca2+ and Pi concentrations modulates oxidative metabolism, and triggers apoptosis of terminally differentiated chondrocytes.

Study on agglutinating factors from flocculent Saccharomyces cerevisiae strains

The lectin-like theory suggest that yeast flocculation is mediated by an aggregating lectinic factor. In this study we isolated an agglutinating factor, which corresponds to lectin, from whole cells by treating the flocculent wild-type Saccharomyces cerevisiae NCYC 625 strain and its weakly flocculent mutant [rho degrees ] with EDTA and two non-ionic surfactants (Hecameg and HTAC). The dialysed crude extracts obtained in this way agglutinated erythrocytes and this hemagglutination was specifically inhibited by mannose and mannose derivatives. However, SDS-PAGE profiles showed that the three reagents had different effects on the yeast cells. The non-ionic surfactants appeared to be the most efficient, as their extracts possessed the highest specific agglutinating activity. The products released by the wild-type strain presented a higher specific agglutinating activity than those released by the [rho degrees ] mutant. Purification of the agglutinating factor from extracts of both strains by affinity chromatography revealed two active bands of relative mass of 26 and 47 kDa on SDS-PAGE. Mass spectrometry analysis by MALDI-TOF, identified a 26 kDa band as the triose phosphate isomerase (TPI) whereas a 47 kDa band was identical to enolase. Edman degradation showed that the N-terminal sequences of these proteins were similar to TPI and enolase, respectively. The difference in the flocculation behaviour of the two strains is due to changes in the protein composition of the cell wall and in the protein structure involved in cell-cell recognition.

Nonionic amphiphilic polymers derived from Tris(hydroxymethyl)-acrylamidomethane keep membrane proteins soluble and native in the absence of detergent

A new family of amphipols-amphiphilic polymers designed to form water-soluble complexes with membrane proteins-was synthesized by free-radical telomerization of Tris(hydroxymethyl)-acrylamidomethane (THAM) and derivatized THAM. Some of these polymers were found to prevent aggregation and denaturation of two model membrane proteins, bacteriorhodopsin and cytochrome b(6) f, in the absence of detergent micelles.

Gene expression profiling following BMP-2 induction of mesenchymal chondrogenesis in vitro

OBJECTIVE

This study aims to apply gene expression profiling technology to gain insight into the molecular regulation of mesenchymal chondrogenesis.

METHODS

The experimental system consists of micromass cultures of C3H10T1/2 cells, a murine multipotential embryonic cell line, treated with the chondroinductive growth factor, bone morphogenetic factor-2 (BMP-2). In this system, chondrogenic differentiation characterized by both morphological changes and cartilage matrix gene expression has been shown to be completely dependent upon BMP-2 treatment and the high cell plating density of micromass cultures. To identify candidate genes that may have key functional roles in chondrogenesis, we have applied subtractive hybridization to isolate genes whose expression is significantly up- or down-regulated during chondrogenesis. RNA was isolated from micromass cultures treated with BMP-2 for 24 h and analysed for representational differences by means of a subtractive hybridization screening method.

RESULTS

Sixteen different genes were identified whose expression was up-regulated between two- and 12-fold by B,P-2, and twelve different genes were identified whose expression was down-regulated between two- and seven-fold by BMP-2.

CONCLUSIONS

The potential of this screening methodology to identify new BMP-2 regulated genes is suggested by the fact that a majority of the identified genes are indeed novel. Identification and characterization of these genes should provide insight as to how chondrogenesis is regulated and also should provide important new markers for the study of osteoarthritis.

A transcriptionally inactive E2F-1 targets the MDM family of proteins for proteolytic degradation

E2F-1-activated transcription promotes cell cycle progression and apoptosis. These functions are regulated by several factors including the E2F-1-binding protein MDM2 and the retinoblastoma protein pRb. Using a yeast two-hybrid screen we have identified the MDM2-related protein, MDMX, as an E2F-1-binding protein. In these studies we find that coexpression of MDMX with E2F-1 results in degradation of the MDMX protein. Although this proteolytic degradation can be blocked by the protease inhibitors bafilomycin A(1), N-acetyl-Leu-Leu-Norleu-AL, and N-acetyl-Leu-Leu-Met-AL, MDMX degradation is not inhibited by lactacystin, suggesting that degradation occurs by a proteasome-independent mechanism. Using an E2F-1 deletion mutant (E2F-1(180-437)) we show that E2F-1-targeted degradation of MDMX does not require the E2F-1 DNA binding domain and therefore is independent of E2F-1-driven transcription. We also find that this transcriptionally inactive E2F-1 mutant is capable of degrading the MDMX-related protein MDM2 and the MDMX isoform MDMX-S. Mapping of the E2F-1 C terminus reveals that neither a previously characterized C-terminal MDM2 binding domain nor the pRb binding domain on E2F-1 is required for MDMX and MDM2 degradation.

Efficient chondrogenic differentiation of mesenchymal cells in micromass culture by retroviral gene transfer of BMP-2

The multipotential murine embryonic C3H10T1/2 mesenchymal cell line is able to undergo chondrogenesis in vitro, in a high density micromass environment, following treatment with soluble human bone morphogenetic protein-2 (BMP-2). To enhance this process, the human BMP-2 cDNA was cloned into a retroviral expression vector and a high titer, infectious retrovirus (replication defective) was generated. Infection of C3HIOT1/2 cells with this retroviral construct resulted in an infection efficiency of 90-95% and was highly effective in converting cells in micromass culture to a chondrocyte phenotype, as assessed by positive Alcian blue staining for extracellular matrix proteoglycans, increased sulfate incorporation, increased expression of the cartilage marker genes collagen type II and aggrecan, and decreased expression of collagen type I. Interestingly, BMP-2 expression in the micromass cultures also induced the expression of the cell cycle inhibitory protein/differentiation factor p21/WAF1, suggesting its functional involvement in chondrogenesis. The chondrogenic effect of retrovirally expressed BMP-2 in these high-density cultures was limited to the infected cells, since uninfected cells did not chondrify when co-cultured as a nonoverlapping micromass adjacent to BMP-2 expressing cells. These data indicate that retrovirally expressed BMP-2 is highly effective at inducing a chondrocyte phenotype in a multipotential mesenchymal cell line in vitro, and its action is restricted to the infected cell population. These findings should provide a framework for the optimization of chondrogenesis in culture using mesenchymal stem cells and retroviral gene transfer.

Constructed wetlands for wastewater treatment in central Italy

The performance of 4 constructed wetlands designed by IRIDRA Srl and operating in Tuscany (central Italy) has been monitored during the last three years. The 4 treatment systems have different sizes and characteristics: one single stage secondary treatment (150 p.e.); two secondary treatment plants with effluent reuse: one small (60 p.e) and the other big (350 p.e.); a tertiary treatment of effluents from an activated sludge plant with high hydraulic load fluctuation (5-500 p.e.). Due to geographical and economic constraints the four systems have high hydraulic and organic loading rates, neverthless the systems show very good removal performance of COD (62-95%), especially the ones with higher inflow COD concentrations (87-95%). Interesting results concerning also removal percentage of MBAS (42-88%) and ammonium (42-85%) were obtained, even though NH4+ concentration in the outflows of some of the plants, doesn't always comply with Italian quality standards.

p27Kip1 expression is associated with clinical outcome in advanced epithelial ovarian cancer: multivariate analysis

Few biological parameters have been shown to have a prognostic role in patients with advanced ovarian cancer. p27Kip1 is a cyclin-dependent kinase inhibitor, and its loss may contribute to tumor progression. We determined whether p27Kip1 protein expression in advanced ovarian cancer could be associated with prognosis. p27Kip1 status was assessed by immunohistochemical analysis of tissue sections from primary tumors of 99 patients with stages III-IV ovarian carcinoma and was analyzed in relation to clinicopathological variables, time to progression (TTP), and overall survival (OS). p27Kip1 expression was detected in 47 (47%) of the 99 patients. p27 expression did not correlate with any of the classical clinicopathological parameters. Loss of p27 protein was significantly associated with a short TTP (P = 0.0004) and decreased OS (P = 0.0302). The 5-year TTP rate in p27-positive patients was 50% versus 11% in p27-negative patients. p27-positive cases showed a 5-year OS rate of 53% compared with 43% of p27-negative cases. In multivariate analysis, p27 expression was an independent predictor of progression of disease (P = 0.0009) and survival (P = 0.0032) when considered together with stage of disease, presence of ascites, and residual tumor at surgery. Loss of p27Kip1 conferred poor prognosis independently of proliferative index, as assessed by proliferating cell nuclear antigen immunostaining. p27 immunoreactivity can be used to predict progression of disease and survival in patients with advanced epithelial ovarian cancer and therefore may represent a new prognostic marker.

Permeability of yeast cell envelope to fluorescent galactosylated telomers derived from THAM

The work reported herein deals with the study of cellular recognition and permeability phenomena in yeasts. Various galactosylated organic telomers derived from trishydroxymethyl-aminomethane (THAM) and bearing fluorescent moieties were synthesized in order to measure their ability to cross the yeast cell envelope. Grafting fluorescent probes on the organic telomer backbone allowed us to study their specific behaviors toward the yeasts by fluorescence microscopy. Yeasts belonging to the genera Kluyveromyces and Saccharomyces were used for this study. With Saccharomyces yeast cells bearing mannose-specific lectins or lectin-like proteins, on their outer surface, all the galactosylated or nongalactosylated organic telomers passed through the cell envelope and invaded the cytoplasm. With Kluyveromyces yeast cells bearing galactose-specific lectins, the galactosylated organic telomers were blocked at the outer surface while the nongalactosylated derivatives crossed the cell envelope. Moreover, preincubation of Kluyveromyces yeasts with galactose or methylgalactose inhibited the cell surface anchorage of the organic telomers and allowed their penetration into the cytoplasm. When assays were performed on spheroplasts of both Kluyveromyces and Saccharomyces yeasts, no fixation on the surface could be observed, and all the derivatives went through the membrane and invaded the cytoplasm.

Cell cycle and apoptosis

In multicellular organisms, cell proliferation and death must be regulated to maintain tissue homeostasis. Many observations suggest that this regulation may be achieved, in part, by coupling the process of cell cycle progression and programmed cell death by using and controlling a shared set of factors. An argument in favor of a link between the cell cycle and apoptosis arises from the accumulated evidence that manipulation of the cell cycle may either prevent or induce an apoptotic response. This linkage has been recognized for tumor suppressor genes such as p53 and RB, the dominant oncogene, c-Myc, and several cyclin-dependent kinases (Cdks) and their regulators. These proteins that function in proliferative pathways may also act to sensitize cells to apoptosis. Indeed, unregulated cell proliferation can result in pathologic conditions including neoplasias if it is not countered by the appropriate cell death. Translating the knowledge gained by studying the connection between cell death and cell proliferation may aid in identifying novel therapies to circumvent disease progression or improve clinical outcome.

Interaction between the lipoamide-containing H-protein and the lipoamide dehydrogenase (L-protein) of the glycine decarboxylase multienzyme system. 1. Biochemical studies

Lipoamide dehydrogenase or dihydrolipoamide dehydrogenase (EC 1.8.1. 4) is the E3-protein component of the mitochondrial 2-oxoacid dehydrogenase multienzyme complexes. It is also the L-protein component of the glycine decarboxylase system. Although the enzymology of this enzyme has been studied exhaustively using free lipoamide as substrate, no data are available concerning the kinetic parameters of this enzyme with its physiological substrates, the dihydrolipoyl domain of the E2 component (dihydrolipoyl acyltransferase) of the 2-oxoacid dehydrogenase multienzyme complexes or the dihydrolipoyl H-protein of the mitochondrial glycine decarboxylase. In this paper, we demonstrate that Tris(2-carboxyethyl)phosphine, a specific disulfide reducing agent, allows a continuous reduction of the lipoyl group associated with the H-protein during the course of the reaction catalysed by the L-protein. This provided a valuable new tool with which to study the catalytic properties of the lipoamide dehydrogenase. The L-protein displayed a much higher affinity for the dihydrolipoyl H-protein than for free dihydrolipoamide. The oxidation of the dihydrolipoyl H-protein was not affected by the presence of structurally related analogues (apoH-protein or octanoylated H-protein). In marked contrast, these analogues strongly and competitively inhibited the decarboxylation of the glycine molecule catalysed by the P-protein component of the glycine decarboxylase system. Small unfolded proteolytic fragments of the H-protein, containing the lipoamide moiety, displayed Km values for the L-protein close to that found for the H-protein. On the other hand, these fragments were not able to promote the decarboxylation of the glycine in the presence of the P-protein. New highly hydrophilic lipoate analogues were synthesized. All of them showed Km and kcat/Km values very close to that found for the H-protein. From our results we concluded that no structural interaction is required for the L-protein to catalyse the oxidation of the dihydrolipoyl H-protein. We discuss the possibility that one function of the H-protein is to maintain a high concentration of the hydrophobic lipoate molecules in a nonmicellar state which would be accessible to the catalytic site of the lipoamide dehydrogenase.

Synthesis and preliminary assessments of ethyl-terminated perfluoroalkyl nonionic surfactants derived from tris(hydroxymethyl)acrylamidomethane

We describe the synthesis and preliminary physicochemical and biological assessments of a new class of nonionic hybrid hydrofluoro amphiphiles derived from tris(hydroxymethyl)aminomethane (THAM). The synthesis of the hydrophobic tail of these amphiphiles is based on the preparation of an asymmetrical hydrofluorocarbon derivative containing an ethyl segment, a fluorocarbon core, and an ethyl thiol moiety. This molecule led to either THAM galactosylated monoadducts or telomers. These amphiphiles exhibit neither detergency toward cell membranes nor membrane protein denaturation.

Paclitaxel induces apoptosis in Saos-2 cells with CD95L upregulation and Bcl-2 phosphorylation

We examined the effect of paclitaxel on human osteoblastic cells Saos-2 to determine if paclitaxel can affect proliferation and apoptosis. We used a p53-negative cell line in order to mimic the loss of function frequently observed at the clinical level. Paclitaxel induced cell death in a dose- and time-dependent manner. Marked nuclear condensation and fragmentation of chromatin were observed by Hoechst 33258 stain, DNA ladder formation, electron microscopy, and flow cytometry at concentrations as low as 100 nM, a concentration which can be achieved by infusion in human plasma. At 100 nM, paclitaxel induced a G2 arrest at 8 h of treatment. The cells then continued to accumulate in G2 until 72 h when the percentage of apoptotic events reached 54%. At the molecular level, Bcl-2 protein was phosphorylated at 16 h and PARP protein was cleaved, indicating the activation of caspase-3-like proteases. Caspase inhibitors Z-VAD-FMK and Z-DEVD-FMK rescued Saos-2 cells from paclitaxel-induced apoptosis. CD95 expression was constantly high, while CD95L showed a threefold increase in expression. This suggests that, following the G2 arrest, apoptosis is induced through the CD95/CD95L system.

Synthesis and surface-active properties of glycosyl carbamates and thioureas

Several amphiphilic glycosyl carbamates, glycosyl thiocarbamates and glycosylthioureas were prepared by addition of the anomeric hydroxyl group of acetylated glycosyl derivatives to alkyl isocyanates, or by reaction of glycosyl isothiocyanates with alcohols or amines. The solubility, critical micelle concentrations and detergent efficiency for the extraction of proteins of these compounds were evaluated and compared.

Frequent loss of expression of the cyclin-dependent kinase inhibitor p27 in epithelial ovarian cancer

p27Kip1 is a member of the Cip1/Kip1 family of cyclin-dependent kinase inhibitors and is a potential tumor suppressor gene. Low levels of p27 are associated with poor prognosis in a variety of tumors, including breast, colon, prostate, and lung carcinomas. In the present study, p27 protein expression was investigated by immunohistochemistry and Western blot analysis in a series of 82 epithelial ovarian tumors [16 classified as low malignant potential (LMP) and 66 classified as primary ovarian adenocarcinomas]. Immunohistochemical analysis revealed frequent loss of p27 expression in primary ovarian adenocarcinomas (33%), with respect to LMP tumors (6%; P = 0.0009). In addition to nuclear staining, cytoplasmic localization of p27 was noted in 45 (55%) of 82 cases. p27 levels inversely correlated with cdk2 kinase activity in a representative subset of tumors. When the clinical outcome of the patients was evaluated in relationship to p27 status, we observed a significant correlation between presence of p27 staining and a longer time to progression (P = 0.032 by log-rank test). These data indicate that loss of p27 is a frequent event in ovarian carcinomas as compared with LMP tumors, suggesting that these tumor types may have different pathogenesis. p27 levels may also represent a useful prognostic marker for predicting disease recurrence in primary ovarian carcinomas.

Cell cycle and cancer

PURPOSE

To evaluate the link between cell cycle dysfunctions and tumor formation.

DESIGN

A review of the cell cycle mechanism and its regulatory factors which are involved in carcinogenesis.

RESULT

Cell duplication is directed by a precise cellular machine. The engine of this machine is composed of the cyclin-dependent kinases (Cdks). Their function mainly consists of phosphorylating the pRb family of proteins to conduct the cell towards a series of events that end in generating two sister cells from one mother cell. The regulation of Cdk activity depends on several cellular proteins that are part of a major system that is able to sense extracellular factors and intracellular signals. Abnormalities in cell cycle regulation and in its checkpoints lead to development of malignant cells. Various components of the cell cycle machinery are mutated, overexpressed or eliminated in several human cancers. Some of them can be even classified as oncogenes or tumor suppressor genes.

CONCLUSIONS

It is necessary to design new antitumoral strategies able to target cells harboring such alterations, in order to understand the events that regulate the cell cycle and its disruption during oncogenesis.

A new class of sulfoxide surfactants derived from Tris. Synthesis and preliminary assessments of their properties

A new class of non-ionic amphiphilic molecules suitable for biological purposes, especially extraction of membrane proteins, is reported. Such surfactants were prepared in two steps: addition of alkyl or fluoroalkyl mercaptan on Tris(hydroxymethyl)acrylamidomethane (THAM) derivatives, followed by the oxydation of sulfide group in sulfoxide moiety in order to provide water solubility to the molecule. The detergent efficiency of these new surfactants were assayed on rat liver cells.

Stabilization of integral membrane proteins in aqueous solution using fluorinated surfactants

Surfactants carrying either a hydrocarbon or a fluorocarbon alkyl chain have been synthesized. The polar head was either tris(hydroxymethyl)acrylamidomethane (THAM), telomerized THAM, or a glycosylated THAM moiety. The aqueous solubility of some of these molecules was increased by oxidizing to a sulfoxide the thioether function that associates their hydrophobic and hydrophilic moieties. In all cases, the critical micellar concentration was principally determined by the length and chemical nature of the alkyl chain. The usefulness of these surfactants in handling integral membrane proteins in solution has been examined using as test materials chloroplast thylakoid membranes and the photosynthetic complex cytochrome b6f. In keeping with earlier observations in other systems, none of the fluorinated surfactants was able to solubilize thylakoid membranes. Transfer to a solution of fluorinated surfactant of b6f complexes that had been solubilized and purified in the presence of a classical detergent usually resulted in aggregation and precipitation of the protein, while most homologous molecules with hydrocarbon chains did keep the b6f complex soluble. Two of the fluorinated surfactants, however, proved able to maintain the b6f complex water-soluble, intact, and enzymatically active. Because of their limited affinity for lipid alkyl chains and other hydrocarbon surfaces, fluorinated surfactants appear as potentially interesting tools for the study of membrane proteins that do not stand well exposure to classical detergents.

Cell targeting by glycosidic telomers. Specific recognition of the Kb CWL1 lectin by galactosylated telomers

This work deals with the synthesis and lectinic recognition ability of galactosylated telomers. To investigate if telomeric carriers could exhibit cellular recognition properties, we have synthesized mono- and polygalactosylated tris(hydroxymethyl)acrylamidomethane (THAM) telomers. The affinity of such macromolecular drug carriers toward a receptor, the yeast Kb CWL1 lectin, was defined, and the influence of mono- or polygalactosylation of THAM units on the recognition phenomenon was assessed. The lectinic affinity of the compounds was estimated by measuring the inhibition of yeast aggregation. The average degree of polymerization as well as the hydrophilic-lipophilic balance of such galactosylated telomers affects their recognition ability for the lectin.

Comparative extraction procedures for a galactose-specific lectin involved in flocculation of Kluyveromyces lactis strains

The extraction of a lectinic factor involved in yeast flocculation, from two Kluyveromyces lactis strains (a flocculent K. lactis 5c and a non-flocculent K. lactis 5a strain) was performed using EDTA and two surfactants, Hecameg and HTAC. The properties of the different extracts were tested by haemagglutination and reflocculation of deflocculated K. lactis 5c cells. Hecameg gave the highest yields of active lectinic extract but the extraction with EDTA seemed more specific. HTAC extracts showed a very low activity. The possibilities of extraction of the agglutinating factor, either by an ion chelator or by surfactants, suggest that this factor may be anchored in the cell envelope, i.e. the cell wall and the membrane, by different mechanisms. All the assays revealed a galactose-specific lectinic activity was present that in the flocculent as well as in the non-flocculent strain. This indicates that the absence of flocculation with K. lactis 5a is mainly due to a defect in the ligands of the lectin rather than to a loss of the lectinic factor itself.

Subcellular distribution of a new fluorinated, biocompatible, non-ionic telomeric carrier: a study in cultured B16 melanoma and rat skin fibroblasts

Tris-hydroxymethyl-amino-methane telomers bearing a fluorinated end have recently been proposed as potential drug carriers. Using ion microscopy, we have investigated the cell uptake and subcellular distribution of a perfluorinated telomere, called F-TAC, in two cell lines, malignant murine B16 melanoma and normal rat skin fibroblasts. Single layer cell cultures on gold plates were incubated with F-TAC at different concentrations. Ion microscopy using mass spectrometry enabled the detection of Fluorine 19 atoms entering into F-TAC constitution. This microanalytical study showed an elective cytoplasmic localization of the molecule, wherein the distribution is relatively homogeneous. Within same culture and incubation conditions, intercellular variations in F-TAC content were very low. In the malignant line, the intracellular concentration remains practically identical when increasing F-TAC concentration in the culture medium above 0.2 mg/ml, indicating that the uptake phenomenon is saturable. In conclusion, the F-TAC telomer easily crosses the plasma membrane, however, it has difficulties in crossing the nuclear membrane. It is likely that intracellular penetration is essentially due to rapid endocytosis of the telomer.

Xenopus laevis ribosomal protein L22: full-length cDNA sequence and expression analysis

A cDNA clone was isolated from a Xenopus laevis embryo library and sequenced. Primer extension experiments indicated the full-length nature of the insert and the encoded product was identified on a two dimensional gel as ribosomal protein (r-protein) L22. The 510-bp L22 cDNA sequence presents short untranslated regions and a 5'-end polypyrimidine tract found in all other vertebrate r-protein mRNA (rp mRNA) so far analyzed. Both the nucleotide (nt) and the deduced amino acid (aa) sequences have been compared with the homologous sequences from other species. The L22 nt sequence is about 70% similar to the mammalian L27a rp mRNA and about 60% homologous to the Drosophila, Tetrahymena and yeast corresponding mRNAs. The 148-aa sequence presents a higher conservation, being 90% similar to the mammalian sequence and more than 70% to the other species. Expression analysis showed that, both during X. laevis embryogenesis and in X. laevis cultured cells during growth-rate changes, L22 synthesis is translationally regulated. Therefore X. laevis L22 mRNA is a new example of the correlation between the polypyrimidine terminal tract and the translational regulation observed in other rp mRNAs.

Vesicles and other supramolecular systems from biocompatible synthetic glycolipids with hydrocarbon and/or fluorocarbon chains

A series of double-tailed hydrocarbon and/or fluorocarbon glycolipids derived from galactose and glucose have been prepared. These compounds were obtained upon opening a lactono- and maltonolactone moiety by the amino group of either a glycine, glycylglycine or lysine residue. The carboxyl terminus of the glycyl and glycylglycine conjugates was further reacted with the appropriate double-tailed amine. In the case of lysine, the lactonamide conjugate was functionalized with a hydrocarbon and/or fluorocarbon fatty amine and acid, respectively. The ability of such glycolipids to disperse in water, the morphology of self-assemblies formed and the stability of the supramolecular structure obtained were shown to depend on the presence or absence and on the nature of the aminoacid spacer. Most of the compounds described were shown by conventional techniques (TEM, Cryo-TEM, LLS, etc.) to produce stable vesicular systems.

Disposition in rat of a new fluorinated, biocompatible, non-ionic telomeric carrier

1. The disposition of the new fluorinated, biocompatible, non-ionic telomeric carrier trisacryl conjugate (F-TAC) labelled with 13C and 14C on the amide function has been studied in the rat after p.o. and i.v. administration. 2. After i.v. administration, excretion measurements have shown that radioactivity was eliminated mainly in the urine (69% within 24 h), and that faecal excretion was low (8% within 72 h). After p.o. administration, faecal elimination was significantly increased (30% within 72 h). No radioactivity was eliminated as 14CO2, after either route of administration. 3. After i.v. administration, plasma radioactivity exhibited a biphasic decrease, with t1/2 = 20 min for the first phase and 29.5 h for the second phase. The maximal plasma concentration was obtained 40 min after oral dosing, followed by a monoexponential decrease with t1/2 = 38.1 h. The ratio AUC (p.o.)/AUC (i.v.) as an assessment of bioavailability was 0.22. 4. After both i.v. and p.o. administration, a relatively homogeneous concentration of radioactivity was found in most organs, close or below the plasma concentration, indicating that tissues do not exhibit a high affinity for this molecule. In addition, F-TAC did not cross the blood-brain barrier. 5. Analysis of urine and plasma on DOWEX AG1X2 anionic resin showed that < 20% of the radioactivity was bound to this support. 13C- and 19F-nmr analysis of the non-bound radioactivity identified it to unchanged F-TAC, with bound radioactivity being due to polyanionic telomers arising from the hydrolysis of the amide function.(ABSTRACT TRUNCATED AT 250 WORDS)

Double-tailed perfluoroalkylated glycolipids as components for drug delivery and targeting systems. Preliminary biocompatibility results

Vesicles are being investigated as drug carriers, especially for enhancing the therapeutic effectiveness of the drug while minimizing its side effects. Drug targeting can be achieved if there is a specific recognition of the vesicle's outer wall by specific cells. With these objectives in mind new glycolipids fitted with fluorinated, hydrogenated or mixed, single and double-tails, containing either a gluco- or a galactopyranose residue in their hydrophilic head, were synthesized and their ability to achieve self-organized supramolecular systems was assessed. Replacement of hydrogen by fluorine in these glycolipids was found to enhance biological tolerance. Thus, a fluorinated single-tailed glycolipid displayed no action on red blood cells at concentrations as high as 50 g/l while its hydrogenated analog was hemolytic at 5 g/l. 100% of survival was obtained one month after intravenous or intraperitoneal injection into mice of isotonic dispersions of single and double-tailed glycolipids at a dose of 500 mg/kg. These glycolipids were innocuous on Namalva cell cultures at a concentration of 0.1 g/l.

Biocompatibility of alkyl and perfluoroalkyl telomeric surfactants derived from THAM

A preliminary, comparative biological evaluation of two new families of non-ionic telomeric surfactants derived from Tris(hydroxymethyl)acrylaminomethane (THAM) is reported. These trisacryl conjugates, or TAC, were designed with the purpose of improving the stability and biocompatibility of fluorocarbon emulsions to be used in injectable oxygen-delivering systems. Their amphiphilic character arises from the simultaneous presence in the same molecule of several hydrophilic THAM residues and of a hydrophobic tail consisting in either a hydrocarbon (H-TAC family) or a fluorocarbon (F-TAC family) chain. The acute toxicity in mice after intravenous injection is low (LD50 in the 625 to 1250 mg/kg body weight range for the H-TAC compared to 630 to 4500 mg/kg body weight range for F-TAC) and increases with the length of the hydrophobic chain. No hemolytic activity was detected for the F-TAC at concentrations up to 200 g/l, while hemolysis is found for the H-TAC at a concentration of 5 g/l or less and increases with the alkyl chain length. The impact of the new surfactants on the growth and viability of Namalva cell cultures also increases with the length of the hydrophobic chain, with again a better tolerance for the F-TAC. Altogether the fluorinated amphiphiles display better tolerance than their hydrocarbon analogs in spite of their significantly increased surface activity. Both families of compounds appear to have potential as strongly hydrophilic surfactants for biomedical applications.