Central neural tumor destruction by controlled release of a synthetic glycoside dispersed in a biodegradable polymeric matrix

Amphiphilic glycoconjugates as potential anti-cancer chemotherapeutics

Amphiphilicity is one of the desirable features in the process of drug development which improves the biological as well as the pharmacokinetics profile of bioactive molecule. Carbohydrate moieties present in anti-cancer natural products and synthetic molecules influence the amphiphilicity and hence their bioactivity. This review focuses on natural and synthetic amphiphilic anti-cancer glycoconjugates. Different classes of molecules with varying degree of amphiphilicity are covered with discussions on their structure-activity relationship and mechanism of action.

Novel sulfoglycolipid IG20 causes neuroprotection by activating the phase II antioxidant response in rat hippocampal slices

Compound IG20 is a newly synthesised sulphated glycolipid that promotes neuritic outgrowth and myelinisation, at the time it causes the inhibition of glial proliferation and facilitates exocytosis in chromaffin cells. Here we have shown that IG20 at 0.3-10 μM afforded neuroprotection in rat hippocampal slices stressed with veratridine, glutamate or with oxygen plus glucose deprivation followed by reoxygenation (OGD/reox). Excess production of reactive oxygen species (ROS) elicited by glutamate or ODG/reox was prevented by IG20 that also restored the depressed tissue levels of GSH and ATP in hippocampal slices subjected to OGD/reox. Furthermore, the augmented iNOS expression produced upon OGD/reox exposure was also counteracted by IG20. Additionally, the IG20 elicited neuroprotection was prevented by the presence of inhibitors of the signalling pathways Jak2/STAT3, MEK/ERK1/2, and PI3K/Akt, consistent with the ability of the compound to increase the phosphorylation of Jak2, ERK1/2, and Akt. Thus, the activation of phase II response and the Nrf2/ARE pathway could explain the antioxidant and anti-inflammatory effects and the ensuing neuroprotective actions of IG20.

Inhibitors of Glioma Growth that Reveal the Tumour to the Immune System

Treated glioblastoma patients survive from 6 to 14 months. In the first part of this review, we describe glioma origins, cancer stem cells and the genomic alterations that generate dysregulated cell division, with enhanced proliferation and diverse response to radiation and chemotherapy. We review the pathways that mediate tumour cell proliferation, neo-angiogenesis, tumor cell invasion, as well as necrotic and apoptotic cell death. Then, we examine the ability of gliomas to evade and suppress the host immune system, exhibited at the levels of antigen recognition and immune activation, limiting the effective signaling between glioma and host immune cells.The second part of the review presents current therapies and their drawbacks. This is followed by a summary of the work of our laboratory during the past 20 years, on oligosaccharide and glycosphingolipid inhibitors of astroblast and astrocytoma division. Neurostatins, the O-acetylated forms of gangliosides GD1b and GT1b naturally present in mammalian brain, are cytostatic for normal astroblasts, but cytotoxic for rat C6 glioma cells and human astrocytoma grades III and IV, with ID50 values ranging from 200 to 450 nM. The inhibitors do not affect neurons or fibroblasts up to concentrations of 4 μM or higher.At least four different neurostatin-activated, cell-mediated antitumoral processes, lead to tumor destruction: (i) inhibition of tumor neovascularization; (ii) activation of microglia; (iii) activation of natural killer (NK) cells; (iv) activation of cytotoxic lymphocytes (CTL). The enhanced antigenicity of neurostatin-treated glioma cells, could be related to their increased expression of connexin 43. Because neurostatins and their analogues show specific activity and no toxicity for normal cells, a clinical trial would be the logical next step.

Lipid and ganglioside alterations in tumor cells treated with antimitotic oleyl glycoside

Oleyl 2-acetamido-2-deoxy-α-D-glucopyranoside (1) was previously shown to exhibit antimitotic activity on glioma (C6) and melanoma (A375) cell lines. Preliminary studies about its mechanism of action using (1)H MAS NMR suggested that 1 may be altering the metabolism of lipids. We have now studied the effect of 1 on the fatty acid, sphingolipid and ganglioside content in a line of carcinomic human alveolar epithelial cells (A549) using UPLC-MS. Oleic acid and NB-DNJ were used as positive controls for inhibition of fatty acid and ganglioside synthesis, respectively. Compound 1 (10 μM) was more efficient than oleic acid in reducing fatty acid levels of A549 cells, producing a decrease in the range of 40-15%, depending on the acyl chain length and the number of insaturations. In addition, glycoside 1 caused a reduction on ganglioside content of A549 tumor cell line and accumulation of lactosylceramide, the common metabolic precursor for ganglioside biosynthesis. Alteration of ganglioside metabolism was also observed with two galactosylated derivatives of 1, which caused a more pronounced increase in lactosylceramide levels. Compound 1 at higher concentrations (above 30 μM) produced drastic alterations in glycosphingolipid metabolism, leading to cell metabolic profiles very different from those obtained at 10 μM. These biochemical changes were ascribed to activation of endoplasmic reticulum stress pathways.

Detection of metabolite changes in C6 glioma cells cultured with antimitotic oleyl glycoside by 1H MAS NMR

The synthetic glycoside, oleyl N-acetyl-alpha-D-glucosaminide (1), was previously shown to exhibit antimitotic activity on rat (C6) and human (U-373) glioma lines. To obtain information about its mechanism of action, metabolite changes in C6 glioma cells were analyzed after treatment with 1 using high-resolution magic angle spinning (1)H NMR. Compound 1 caused either a decrease or an increase in the intensity of the signal assigned to coenzyme A (CoA) metabolites depending on the concentration used. The data obtained from the (1)H NMR spectra of cells cultured with 1, combined with those obtained after treatment with oleic acid (an inhibitor of acetyl-CoA carboxylase) and phenyl butyrate (a known antineoplastic agent), suggest that 1 may be altering the metabolism of fatty acids and induce apoptosis of C6 glioma cells. These results point to NMR spectroscopy as an efficient technique for monitoring the response of the cells to therapeutic agents.

Design and synthesis of glycoside inhibitors of glioma and melanoma growth

An N-acetylglucosaminide derivative with a pentaerythritol substituent at position C-6 was previously synthesized and shown to inhibit neural tumor growth. Now, we report the preparation of a series of new synthetic compounds introducing systematic changes in the nature, polarity, and size of the sugar substituents. The antimitotic activity of the new compounds was tested on cultured rat (C6) and human (U-373) glioma lines and on a human melanoma line (A-375). The antimitotic and antitumoral activity of the new compounds on glioma cell lines increased up to 2 orders of magnitude with respect to the parent compound or was abolished, permitting a detailed structure-function analysis of the new antitumorals. One of the glycosides inhibited melanoma division with an ID50 below the micromolar range.

Inhibiting human astrocytoma growth: structure-activity relationships in neurostatin related glycolipids

Neurostatin, a mammalian brain inhibitor of division of astroblast and astrocytoma cells, was characterized as the disialoganglioside GD1b, 9-O-acetylated on the outer sialic acid residue (Galbeta1-->3GalNAcbeta1-->4(9-O-Ac-NeuAcalpha2-->8NeuAcalpha2-->3)Galbeta1-->4Glcbeta1-->1'-ceramide). Using semisynthetic approaches, we prepared and tested different gangliosides O-acetylated in the sialic acid and compared them to non-O-acetylated partners as inhibitors of U-373 glioma cells. Athough the O-acetylation of the sialic acid was the most important molecular feature for the antiproliferative activity of O-acetylated gangliosides, monosaccharide links Galbeta1--> 3GalNAcbeta1 and NeuAcalpha2-->8NeuAcalpha2 enhanced the inhibitory activity.

A highly toxic morphine-3-glucuronide derivative

By the coupling of octylamine to the uronic acid function of morphine-3-glucuronide (M3G) a new glycoconjugate (morphine-3-octylglucuronamide, M3GOAM) was prepared. When assayed in both rats and mice up to ng/kg (i.p.) doses none of the animals survived. The aliphatic octyl chain may be the lethal factor since a closely related derivative (M3GNH2), was not toxic and showed similar opioid antagonist properties than naloxone.